Anemia, chronic renal disease and congestive heart failure--the cardio renal anemia syndrome: the need for cooperation between cardiologists and nephrologists.

Many patients with congestive heart failure (CHF) fail to respond to maximal CHF therapy and progress to end stage CHF with many hospitalizations, poor quality of life (QoL), progressive chronic kidney disease (CKD) which can lead to end stage kidney disease (ESKD), or die of cardiovascular complications within a short time. One factor that has generally been ignored in many of these people is the fact that they are often anemic. The anemia in CHF is due mainly to the frequently-associated CKD but also to the inhibitory effects of cytokines on erythropoietin production and on bone marrow activity, as well as to their interference with iron absorption from the gut and their inhibiting effect on the release of iron from iron stores. Anemia itself may further worsen cardiac and renal function and make the patients resistant to standard CHF therapy. Indeed anemia in CHF has been associated with increased severity of CHF, increased hospitalization, worse cardiac function and functional class, the need for higher doses of diuretics, progressive worsening of renal function and reduced QoL. In both controlled and uncontrolled studies of CHF, the correction of the anemia with erythropoietin (EPO) and oral or intravenous (IV) iron has been associated with improvement in many cardiac and renal parameters and an increased QoL. EPO itself may also play a direct role in improving the heart unrelated to the improvement of the anemia--by reducing apoptosis of cardiac and endothelial cells, increasing the number of endothelial progenitor cells, and improving endothelial cell function and neovascularization of the heart. Anemia may also play a role in the worsening of acute myocardial infarction and chronic coronary heart disease (CHD) and in the cardiovascular complications of renal transplantation. Anemia, CHF and CKD interact as a vicious circle so as to cause or worsen each other- the so-called cardio renal anemia syndrome. Only adequate treatment of all three conditions can prevent the CHF and CKD from progressing.

Impaired nitric oxide production, brachial artery reactivity and fish oil in offspring of ischaemic heart disease patients.

The offspring of coronary heart disease (CHD) patients are at particularly high risk for developing CHD. Endothelial dysfunction is present in the majority of CHD and atherosclerosis patients. Fish oil, rich in n-3 fatty acids has been shown to augment endothelium-dependent vasodilatation in human peripheral and coronary arteries. The aims of this study are to investigate presence of endothelial dysfunction determined by the brachial flow-mediated diameter, nitric oxide, plasma lipids and fibrinogen, and the effect of high doses of fish oil on these parameters. Twenty-four healthy offspring of CHD patients (study group) were supplemented with 9 g/day Alsepa fish oil (each gram containing 180 mg EPA and 120 mg DHA), for a period of two weeks. Plasma nitric oxide, urine nitric oxide, fibrinogens and flow-mediated vasodilatation (FMD) were determined prior to fish oil therapy, two weeks into therapy and four weeks after the end of therapy with fish oil. Twelve healthy subjects (control group) with no family history of heart disease were studied as controls (day one only). The offspring had a lower increase in FMD and lower nitric oxide production, compared with the control group. No other parameters varied between the two groups. The administration of fish oil did not result in any changes in the studied parameters. In healthy offspring of CHD patients, early endothelial dysfunction was documented before evidence of atherosclerosis. Ingestion of fish oil over a 13-day period did not improve endothelial dysfunction.

Effects of an acute dose of L-arginine during coronary angiography in patients with chronic renal failure: a randomized, parallel, double-blind clinical trial.

BACKGROUND: Contrast media (CM) are nephrotoxic and might further worsen renal function in patients with chronic renal failure. L-Arginine, the substrate of nitric oxide, protects kidney function and may improve endothelial function in patients with coronary artery disease. HYPOTHESIS: Acute administration of L-arginine in a subset of patients with combined coronary artery disease and impaired kidney function during coronary angiography might prevent superimposed acute renal failure. METHODS: A double-blind study of patients with mild/moderate chronic renal failure (Cr >1.7 mg/dl) undergoing coronary angiography (meglumine ioxaglate) was conducted. Patients received either L-arginine (300 mg/kg) or placebo and were followed for 48 h. Cardiac hemodynamic parameters, renal function and nitric oxide production were sequentially recorded. RESULTS--PRIMARY AND SECONDARY: Both groups experienced a decrease of creatinine clearance 48 h following the procedure (p < 0.05). Creatinine levels slightly increased following the administration of L-arginine (p < 0.05) but not in the placebo treated group. No changes of systemic and cardiac pressures, total peripheral resistance or cardiac output were recorded within and between the treatment and placebo groups. CONCLUSION: CM injection causes an impairment of renal function. Addition of intravenous L-arginine during cardiac catheterizations in patients with chronic renal failure does not prevent CM-induced nephrotoxicity and does not affect endothelial dysfunction in the particular population studied by the authors, i.e. patients with coronary artery disease (CAD) of various degrees, or suspicion of CAD and chronic mild renal failure.

Protamine-induced cardiotoxicity is prevented by anti-TNF-alpha antibodies and heparin.

BACKGROUND: We investigated the role of tumor necrosis factor alpha (TNF-alpha) in protamine-induced cardiotoxicity and the possibility of preventing or decreasing this effect by anti TNF-alpha antibodies and heparin. METHODS: Isolated rat hearts were perfused for 60 min with Krebs-Henseleit solution (KH). The control group was perfused with KH alone, the KH > protamine > KH group was treated from the 20th to the 40th minute with protamine, and the KH + anti-TNF > protamine + anti-TNF > KH + anti-TNF group was treated the same as the KH > protamine > KH group but with anti-TNF-alpha antibodies added throughout perfusion. The KH + heparin > protamine + heparin > KH + heparin group was treated the same as the KH > protamine > KH group but with heparin added to KH throughout perfusion. The KH > protamine > KH + heparin was perfused the same as the KH> protamine > KH group but with heparin added to KH for the last 20 min. Left ventricular (LV) function and coronary flow were measured every 10 min. TNF-alpha was measured in the coronary sinus effluent. Left ventricular TNF messenger RNA was determined in the control and KH > protamine > KH groups at baseline and after the 40-min perfusion. RESULTS: Protamine caused a significant decrease of peak systolic pressure and dP/dt (to 25% of baseline). Significant amounts of TNF-alpha in the effluent in the KH > protamine > KH group (102.3 +/- 15.5 pg/min) and TNF messenger RNA expression in left ventricular samples were detected. TNF-alpha was below detectable concentrations in the control, KH + anti-TNF > protamine + anti-TNF > KH + anti-TNF, and KH + heparin > protamine + heparin > KH + heparin groups. TNF-alpha concentrations correlated with depression of LV peak systolic pressure (r = 0.984; P = 0.01) and first derivate of the increase of LV pressure (r = 0.976; P = 0.001). Heparin improved LV recovery and decreased protamine-induced TNF-alpha release (KH > protamine > KH + heparin group). CONCLUSIONS: Anti-TNF-alpha antibodies and heparin prevent protamine-induced TNF-alpha release and depression of LV function. Heparin improves protamine-induced depression of cardiac function.

Vasoactive intestinal peptide and related molecules induce nitrite accumulation in the extracellular milieu of rat cerebral cortical cultures.

Nanomolar concentrations of vasoactive intestinal peptide (VIP), picomolar concentrations of stearyl-norleucine17-VIP (SNV) and femtomolar concentrations of NAPVSIPQ (NAP), an 8-amino-acid peptide derived from the VIP-responsive activity-dependent neuroprotective protein, provide broad neuroprotection. In rat cerebral cortical cultures, 10(-16)-10(-7) M NAP increased intracellular cyclic guanosine monophosphate (cGMP) (2.5-4-fold) and 10(-10) M NAP increased extracellular nitric oxide (NO) by 60%. In the same culture system, VIP and SNV (at micromolar concentrations) increased extracellular NO by 45-55%. The NAP dose required for cGMP increases correlated with the dose providing neuroprotection. However, the concentrations of NAP, SNV and VIP affecting NO production did not match the neuro-protective doses. Thus, NO may mediate part of the cell-cell interaction and natural maintenance activity of VIP/SNV/NAP, while cGMP may mediate neuroprotection.

The effect of agmatine administration on ischemic-reperfused isolated rat heart.

BACKGROUND: The natural polyamine Agmatine (Ag) plays a significant role in protection of nerve cell ischemic injury. A previous report indicated that Ag given intraperitoneally to rats enhanced the recovery of the heart from ischemic injury. Based on this initial observation, a larger investigation was undertaken to explore a dose-response effect and possible mechanisms underlying the protective effects. METHODS: Using the modified Langendorff model, 36 isolated hearts were divided into five groups: group 1, hearts receiving 100 microM/L Ag pre-ischemia (n=7); group 2, hearts receiving 100 microM/L Ag pre- and post-ischemia, (n=7); group 3, hearts receiving 250 microM/L Ag pre-ischemia (n=7); group 4, hearts receiving 250 microM/L Ag pre- and postischemia (n=7); and group 5, hearts receiving Krebs-Hensleit solution served as control (n=8). The study design included 20 minutes of perfusion, 30 minutes of global ischemia, and 30 minutes of reperfusion. RESULTS: After ischemia, group 2 developed higher left ventricular pressure P(max) (P<0.01), improved first-derivative of the rise (dP/dt max; P<0.02), and fall (dP/dt min; P<0.04) in left ventricular pressure, and the area calculated under the left-ventricle developed pressure curve (pressure-time integral; P<0.015), but coronary flow was not significantly increased (P=0.06) compared to the control group. Group 1 had improved diastolic recovery: dP/dt min (P<0.05) and coronary flow (P<0.03), compared with the control group. Group 3 had improved P(max) (P<0.01), dP/dt min (P<0.01), and coronary flow (P<0.02); group 4 had no improvement in all hemodynamic parameters. CONCLUSION: Low doses of Ag given pre- and post-ischemia, and high doses given only pre-ischemia have favorable, protective effects on the hemodynamic recovery of isolated rat heart undergoing global ischemia and reperfusion.

Protamine cardiotoxicity and nitric oxide.

OBJECTIVES: The purpose of this study is to assess the role of the nitric oxide (NO) pathway in protamine-induced cardiotoxicity and to formulate a possible explanation for this adverse effect. METHODS: Isolated rat hearts were perfused by Krebs--Henseleit (KH) solution using a modified Langendorff model. They were randomized into three groups: A, 40 min perfusion with KH solution; B, 20 min perfusion with KH solution and 20 min with protamine; C, as B but Ng-monomethyl-L-arginine (L-NMMA), a non-selective inhibitor of the NO pathway, was added during 40 min of the perfusion period. Left ventricular (LV) function was measured every 10 min. NO and tumor necrosis factor-alpha (TNF) were detected in the effluent from the coronary sinus (CS) and in the supernatant of the cardiac myocytes culture. Nitric oxide synthases (NOS) mRNA levels were determined in groups A and B from LV samples at baseline and after 40 min of perfusion. RESULTS: We found that protamine at a dose of 12 microg/ml causes significant depression of LV function (decreased peak systolic pressure to 22.5+/-3.2% and dP/dt max to 22.9+/-3.1%). L-NMMA did not prevent protamine cardiotoxicity. NOS mRNA was not detected from LV samples in any group. The NO in the effluent from the CS and from the supernatant of the cardiomyocytes culture was below detectable levels. However, a significant amount of TNF was measured in the effluent from the CS (108+/-17 pg/min for group B and 117+/-13 pg/min for group C) and in the supernatant of the cardiomyocytes culture (65+/-21 pg/ml). CONCLUSIONS: This study suggests that direct protamine-induced cardiotoxicity does not depend on the NO pathway. Our finding that protamine induced TNF release by cardiomyocytes can shed new light on the understanding of protamine cardiotoxicity.

Methylene blue, a nitric oxide inhibitor, prevents haemodialysis hypotension.

BACKGROUND: Plasma nitric oxide (NO) levels have been found to be high in haemodialysis (HD) patients, especially in those prone to hypotension in dialysis. The aim of the study was to prevent dialysis hypotension episodes by i.v. administration of methylene blue (MB), an inhibitor of NO activity and/or production. METHODS: MB was given i.v. in 18 stable HD patients with hypotensive episodes during almost every dialysis, in 18 HD patients without hypotension during dialyses, and in five healthy controls. MB was given as a bolus of 1 mg/kg bodyweight followed by a constant infusion of 0.1 mg/kg bodyweight lasting 210 min until the end of the dialysis session and only as a bolus on a non-dialysis day. Systolic and diastolic blood pressures (BP) were measured at 10-min intervals during HD sessions with or without MB and on a non-dialysis day with MB. RESULTS: In hypotension-prone patients, MB completely prevented the hypotension during dialysis and increased both systolic and diastolic BP on non-dialysis days. In normotensive patients, MB increased BP during the first hour of dialysis and for 90 min on the non-dialysis day. The BP in the healthy controls remained unchanged. Plasma and platelet NO(2)+NO(3) (stable metabolites of NO) levels were determined. The NO(2)+NO(3) generation rate in the first post-dialysis day was calculated. The plasma and platelet NO(2)+NO(3) were higher in the hypotensive group than in the normotensive dialysis group. The generation rate of nitrates was higher (P<0.01) in the hypotensive group (1.21+/-0.13 micromol/min and 0.74+/-0.16 after MB) than in the normotensive patients (0.61+/-0.11 micromol/ min and 0.27+/-0.14 after MB). No side-effects were recorded. CONCLUSIONS: MB is an efficient therapy in the prevention of dialysis hypotension.

Tetrahydrobiopterin augments arginine transport in rat cardiac myocytes through modulation of CAT-2 mRNA.

Tetrahydrobiopterin (BH4) has been shown to be required for dimerization and acquisition of nitric oxide (NO) generating capacity by nitric oxide synthase (NOS). In the present study we have investigated the hypothesis that BH4 may affect NOS activity through a novel mechanism-namely, modulating arginine transport in rat cardiac myocytes. Cardiac myocytes have been previously shown to express cationic amino acid transport proteins (y+ system) CAT-1 and CAT-2. Increasing extracellular BH4 concentrations up to 0.5 mmol/L augments arginine transport in 1 mmol/L arginine media (no BH4, 558 +/- 42 fmol arginine/microg protein/min; 0.1 mmol/L BH4, 580 +/- 11 fmol arginine/microg protein/min; 0.5 mmol/L BH4, 944 +/- 71* fmol arginine/microg protein/min; 1.0 mmol/L BH4, 983+/-84* fmol arginine/microg protein/min, n = 4; *: P <.05 vs no BH4). Treating the cells with lipopolysaccharide (LPS) (10 microg/mL) significantly augmented arginine transport only in the presence of BH4 (no BH4, 600 +/- 33 fmol arginine/microg protein/min; 0.1 mmol/L BH4, 691 +/- 29*dagger fmol arginine/microg protein/min; 0.5 mmol/L BH4, 1123 +/- 32*dagger fmol arginine/microg protein/min; 1.0 mmol/L BH4, 1296 +/- 42*dagger fmol arginine/microg protein/min, n = 4; *: P <.01 vs no BH4, dagger: P <.05 vs no LPS). The administration of biopterin, sodium nitroprusside (NO donor), 2,4-diamino-6-hydroxy-pyrimidine (inhibitor of BH4 synthesis), and sepiapterin (the precursor of de novo synthesis of BH4) to unstimulated cells had no effect on arginine uptake values. Using reverse trancriptase-polymerase chain reaction, we next studied the steady state levels for CAT-1 and CAT-2 mRNA. Incubation with BH4 significantly increased CAT-2 mRNA expression in a concentration-dependent manner in 0.1, 0.5, and 1 mmol/L BH4, respectively. Northern blotting analysis further confirmed this observation. We also found that in the presence of BH4 in these concentrations, CAT-1 mRNA expression was abolished. We suggest that BH4 augments intracellular arginine availability by modulating CAT-2 mRNA expression and suggest that its presence is required for the LPS effect on trans-membrane arginine traffic.

Down regulation of interleukin 1beta production in human osteoarthritic synovial tissue and cartilage cultures by aminoguanidine.

OBJECTIVE: To evaluate the effect of aminoguanidine (AG) on de novo interleukin 1beta (IL1beta), nitric oxide (NO), and interleukin 1 receptor antagonist (IL1ra) production by osteoarthritic human synovial tissue and articular cartilage cultures. METHODS: Synovial tissue and cartilage, obtained during surgery from 29 patients undergoing total knee or hip replacement for osteoarthritis, were cut into small pieces and cultured in the presence or absence of lipopolysaccharide (LPS) and test materials. IL1beta, IL1ra, and NO were determined in culture media. The inducible nitric oxide synthase inhibitor, AG, was added to cultures in various concentrations (0.3-3 mmol/l). RESULTS: In synovial tissue cultures AG (0.3, 1, and 3 mmol/l) decreased LPS (1 microg/ml) stimulated IL1beta and NO release in the media in a dose dependent manner (p<0.05 at 1 mmol/l and p<0.05 at 0.3 mmol/l, respectively). In articular cartilage cultures AG (0.3, 1, and 3 mmol/l) decreased LPS (1 microg/ml) stimulated IL1beta and NO release in the media in a dose dependent manner (p<0.05 at 1 mmol/l and p<0.01 at 0.3 mmol/l, respectively). Hydrocortisone (5 microg/ml) also significantly decreased LPS stimulated IL1beta release in media of synovial tissue and cartilage cultures and NO in media of synovial cultures. AG (0.3, 1, and 3 mmol/l) decreased LPS (1 microg/ml) stimulated IL1ra levels in media of synovial tissue cultures in a dose dependent manner (p<0.05 at 1 mmol/l) but increased LPS (1 microg/ml) stimulated IL1ra release in media of cartilage cultures (p<0.01 at 3 mmol/l). The NO donor, nitroprusside (10, 30, 100, and 300 microg/ml) stimulated IL1beta release in media of synovial tissue cultures in a dose dependent manner (p<0.01 at 100 microg/ml). AG and nitroprusside at the concentrations used had no toxic effect on human synovial cells. CONCLUSIONS: NO synthase inhibitors may modulate osteoarthritis and articular inflammatory processes not only by decreasing NO synthesis but also by their effects on ILbeta and IL1ra production.

Interaction between paracrine tumor necrosis factor-alpha and paracrine angiotensin II during myocardial ischemia.

OBJECTIVES: The purpose of this study was to explore interactions between paracrine angiotensin II (Ang-II) and tumor necrosis factor-alpha (TNF-alpha) during myocardial ischemia. BACKGROUND: Ischemic myocardium releases significant amounts of TNF-alpha. This paracrine release correlated with postischemic myocardial injury. Other studies showed myocardial protection obtained by the use of angiotensin-converting enzyme inhibitors (i.e., captopril) and the Ang-II type 1 receptor antagonist losartan after ischemia. The possibility that these agents decrease TNF-alpha synthesis has not yet been investigated. METHODS: Using the modified Langendorff model, isolated rat hearts underwent either 90 min of nonischemic perfusion (control group) or 1 h of global cardioplegic ischemia. In both groups, either captopril (360 micromol/liter) or losartan (182.2 micromol/liter) was added before ischemia. The hearts were assayed for messenger ribonucleic acid (mRNA) expression and effluent TNF-alpha levels. In addition, cardiac myocytes were incubated in cell culture with Ang-II. RESULTS: After ischemia, TNF-alpha mRNA expression intensified from 0.63 +/- 0.06 (control group) to 0.92 +/- 0.12 (p < 0.03), and effluent TNF-alpha levels were 711 +/- 154 pg/ml. The TNF-alpha mRNA expression declined to 0.46 +/- 0.07 (p < 0.01) and 0.65 +/- 0.08 (p < 0.02) in captopril- and losartan-treated hearts, respectively. Effluent TNF-alpha was below detectable levels. Concentrations of TNF-alpha in supernatants of incubated cardiac myocytes treated with 10 and 50 nmol/liter of Ang-II were 206.0 +/- 47.0 pg/ml and 810 +/- 130 pg/ml, respectively (p < 0.004). When pretreated with 700 micromol/liter of losartan, TNF-alpha was below detectable levels. CONCLUSIONS: This study presents an original explanation for previously reported myocardial protection after ischemia, obtained by the use of captopril and losartan. These drugs reduce TNF-alpha synthesis, providing strong evidence of active interactions between paracrine TNF-alpha and Ang-II in the evolution of the ischemic cascade.

Cloning and characterization of the human activity-dependent neuroprotective protein.

We have recently cloned the mouse activity-dependent neuroprotective protein (ADNP). Here, we disclose the cloning of human ADNP (hADNP) from a fetal brain cDNA library. Comparative sequence analysis of these two ADNP orthologs indicated 90% identity at the mRNA level. Several single nucleotide polymorphic sites were noticed. The deduced protein structure contained nine zinc fingers, a proline-rich region, a nuclear bipartite localization signal, and a homeobox domain profile, suggesting a transcription factor function. Further comparative analysis identified an ADNP paralog (33% identity and 46% similarity), indicating that these genes belong to a novel protein family with a nine-zinc finger motif followed by a homeobox domain. The hADNP gene structure spans approximately 40 kilobases and includes five exons and four introns with alternative splicing of an untranslated second exon. The hADNP gene was mapped to chromosome 20q12-13.2, a region associated with aggressive tumor growth, frequently amplified in many neoplasias, including breast, bladder, ovarian, pancreatic, and colon cancers. hADNP mRNA is abundantly expressed in distinct normal tissues, and high expression levels were encountered in malignant cells. Down-regulation of ADNP by antisense oligodeoxynucleotides up-regulated the tumor suppressor p53 and reduced the viability of intestinal cancer cells by 90%. Thus, ADNP is implicated in maintaining cell survival, perhaps through modulation of p53.

Glomerular basement membrane polyanion distribution and nitric oxide in spontaneous hypertensive rats: effects of salt loading and antihypertensive therapy with propranolol.

Cationic colloidal gold (CCG), a polycationic histochemical probe, was used to analyze the distribution of glomerular basement membrane (GBM) polyanions, mainly heparan sulfate proteoglycan in spontaneous hypertensive rats (SHR) with or without salt loading and antihypertensive treatment with propranolol. The changes of mean GBM width and anionic sites distribution were assessed by electron microscopy. Plasma and urinary nitrates (NO(x)) were measured by nitrite (NO2) + nitrate (NO3), stable metabolites of NO. SHR had decreased NO production and increased GBM width (27%) compared with the control Wistar-Kyoto (WKY) rats. The chronic high dietary salt intake resulted in a significant increase in blood pressure, proteinuria, and renal function in the SHR rats. The chronic high salt dietary intake resulted in a decrease in NO in the WKY and a further reduction in NO production in the SHR. The GBM anionic sites count was similar in the SHR and WKY nonsalt-loaded groups, 13.5 +/- 0.5 and 12.8 +/- 0.4 CCG counts/microm GBM, respectively, but significantly lower in both salt-loaded SHR and WKY, 9.9 +/- 0.55 (P < .01) and 9.6 +/- 0.55 (P < .01) CCG counts/microm GBM, respectively. Antihypertensive treatment with propranolol in the salt-loaded SHR group resulted in lower blood pressure, a further decrease in NO production, but no significant changes in GBM width and anionic sites count. It is concluded that chronic high salt intake may be deleterious to the permselectivity of the GBM. A low NO production state that results from chronic salt loading in already hypertensive rats will result in more severe organ (renal) damage, most probably by the addition of the loss of GBM permselectivity to the existing pathomorphologic changes.

Renal nitric oxide production during the early phase of experimental diabetes mellitus.

BACKGROUND: Diabetic nephropathy (DN) is characterized by hyperfiltration and hypertrophy in experimental models of diabetes mellitus (DM). Several studies have demonstrated that the pathophysiologic and morphologic changes in DN are mediated by either an increase or decrease in renal nitric oxide (NO) production and/or activity. The goal of the present study was to determine the effects that the early diabetic state has on NO production in the kidney of rats with streptozotocin-induced DM. METHODS: Experimental DM was induced in rats with streptozotocin. Urinary NO production was measured, and levels and activity of the different NOS isoforms were determined by a combination of techniques, including immunoblotting, immunohistochemistry, diaphorase staining, and reverse transcription-polymerase chain reaction. RESULTS: During the first week of DM, urinary NO metabolites (uNO2 + NO3) were reduced as compared with controls, which were unrelated to changes in serum levels of NO. Total NO synthase (NOS) activity was reduced in the renal cortex beginning at 30 hours after the induction of DM. NADPH diaphorase staining of renal cortical slices showed reduced NOS activity in the macula densa in diabetic animals. By immunohistochemical staining with antibodies to the different isoforms of NOS, it was found that protein levels of the neuroneal NOS (nNOS) isoform was diminished in the macula densa. No changes were found in the levels of endothelial NOS (eNOS) activity and protein in the renal cortex in the early diabetic state. CONCLUSIONS: This study provides strong evidence that renal production of NO is reduced in early DM and that this reduction is associated with decreased levels of nNOS activity and protein in the macula densa.

Glomerular basement membrane anionic sites in adriamycin nephropathy: effect of saline loading and nitric oxide modulation.

BACKGROUND: In previous studies we found that experimental Adriamycin (ADR) nephropathy is associated with the loss of glomerular basement membrane (GBM) anionic sites provided by heparan sulfate proteoglycans. Chronic saline loading in normal rats resulted in a similar effect on the GBM anionic sites. The L-arginine-nitric oxide synthase-nitric oxide system is involved in the pathogenesis of experimental chronic renal failure. The present study was performed to determine the combined effect of nitric oxide (NO) modulation and chronic saline loading in ADR nephropathy. The modulation of NO was done by chronic administration of L-arginine (NO donor) or N(w)-nitro-L-arginine, a known nitric oxide synthase inhibitor. METHODS: Systolic blood pressure was measured in awake rats by a tail-cuff method. Renal function was assessed by creatinine clearance, FeNa%, and daily protein excretion. The change of mean GBM widths and anionic sites distribution were assessed by electron microscopy. The localization of anionic sites was carried out by cationic colloidal gold. Plasma and urinary nitrates (NO(x)) were measured by nitrite (NO(2)) + nitrate (NO(3)), stable metabolites of NO. RESULTS: Two weeks after the ADR administration (3.5 mg/kg BW iv) the rats had severe renal failure (creatinine clearance 134 +/- 31 microl/min/100 g BW vs. initial values 670 +/- 29 microl/min/ 100 g BW, p < 0.001), high FeNa%, severe proteinuria, increased GBM width, significant reduction of GBM anionic sites and low urinary NO(x) excretion. The saline loading resulted in further reduction of GBM anionic sites count and blood pressure elevation. The inhibition of NO did not change the course of ADR nephropathy. The main finding of the present study is that chronic administration of L-arginine significantly alleviates the renal failure in the ADR (+/- saline loading) nephropathy. The L-arginine-treated rat had higher creatinine clearance, lower FeNa% and protein excretion and complete normalization of GBM anionic sites distribution. CONCLUSIONS: Sodium loading has a deleterious effect on GBM permselectivity. L-Arginine prevents the reduction of GBM anionic sites, decreases proteinuria and alleviates the renal insufficiency in ADR nephropathy.

Captopril and L-arginine have a synergistic cardioprotective effect in ischemic-reperfusion injury in the isolated rat heart.

OBJECTIVES: The present study was designed to evaluate the possible effect of the combined administration of both captopril (Cap) and L-arginine (L-a) in the isolated ischemic rat heart model. BACKGROUND: Recent studies suggest that L-arginine and angiotensin-converting enzyme (ACE) inhibitors possess independent cardioprotective effects in ischemic hearts. The pharmacological effect of the combination of both drugs has not yet been investigated in the ischemic myocardium. METHODS: Using the modified Langendorf model, rats were perfused with either Cap 360 micromol/L (n = 6) or (L-a) 3mmol/L (n = 6), both captopril and L-arginine (Cap+L-a) (n = 8), or saline control (Con) (n = 8). The study design included 30 minutes of perfusion, 30 minutes of global ischemia, and 30 minutes of reperfusion thereafter. RESULTS: Hearts treated with both Cap+L-a demonstrated an improved performance in all parameters. After 10 minutes of reperfusion, the P(max) in the Cap+L-a group was 98 +/- 8 mmHg (P <.001), 59 +/- 14 mmHg in the Cap group (P <.02), and 44.3 +/- 10 mmHg in the L-a group (P = NS), compared with only 42 +/- 8 mmHg in the control. After 10 minutes of reperfusion the dP/dt(min) was: in the Cap+L-a group: -1,650 +/- 223 mmHg/s (P <. 006); in the Cap group: -1,051 +/- 302 mmHg/s (P <.03); in the L-a group: -870 +/- 131 mmHg/s (P = NS), compared with only -487 +/- 131 mmHg/s in the control. Coronary flow was significantly increased in all 3 groups: Cap+L-a group: 22.3 +/- 1.5 mL/min (P <.001); Cap group: 18 +/- 1.6 mL/min (P <.01); L-a group: 19.8 +/- 0.9 mL/min (P <.02), compared with 12.6 +/- 0.9 mL/min in the Con group. Total NO level was significantly increased in the Cap+L-a group: 13.4 +/- 2 micromol (P <.03) vs. 6.1 +/- 1 micromol for the L-a group. NO levels of both the Cap group and the Con group were beneath detectable values. CONCLUSION: Combined administration of captopril and L-arginine has a synergistic, protective effect on heart function and coronary flow that may be mediated by enhanced NO production.

Effect of oral administration of high-dose nitric oxide donor L-arginine in men with organic erectile dysfunction: results of a double-blind, randomized, placebo-controlled study.

OBJECTIVES: To determine, in a prospective randomized, double-blind placebo-controlled study, the effect of 6 weeks of high-dose (5 g/day) orally administered nitric oxide (NO) donor L-arginine on men with organic erectile dysfunction (ED). PATIENTS AND METHODS: The study included 50 men with confirmed organic ED who were randomized after a 2-week placebo run-in period to receive L-arginine or placebo. A detailed medical and sexual history, O'Leary's questionnaire, a specially designed sexual function questionnaire and a sexual activity diary were obtained for each patient. All participants underwent a complete physical examination including an assessment of bulbocavernosus reflex and penile haemodynamics. Plasma and urine nitrite and nitrate (designated NOx), both stable metabolites of nitric oxide, were determined at the end of the placebo run-in period, and after 3 and 6 weeks. RESULTS: Nine of 29 (31%) patients taking L-arginine and two of 17 controls reported a significant subjective improvement in sexual function. All objective variables assessed remained unchanged. All nine patients treated with L-arginine and who had subjectively improved sexual performance had had an initially low urinary NOx, and this level had doubled at the end of the study. CONCLUSIONS: Oral administration of L-arginine in high doses seems to cause significant subjective improvement in sexual function in men with organic ED only if they have decreased NOx excretion or production. The haemodynamics of the corpus cavernosum were not affected by oral L-arginine at the dosage used.

Pregnancy decreases immunoreactive parathyroid hormone level in rats with chronic renal failure.

Normal pregnancy is associated with an increase in serum parathyroid hormone and 1,25-dihydroxyvitamin D3 (calcitriol). The effect of pregnancy on these hormones in chronic renal failure (CRF) is unknown. The present work was undertaken to study the changes of serum immunoreactive parathyroid hormone (iPTH) and calcitriol in pregnant rats with CRF. The following experimental groups were studied: CRF1 (5/6 nephrectomized virgin female rats), CRF2 (5/6 nephrectomized pregnant rats at day 20-21 of pregnancy), CRF3 (5/6 nephrectomized rats 2 weeks after delivery) and their respective sham-operated control groups: N1, N2 and N3. The 5/6 nephrectomy (CRF1) resulted in renal failure with very high serum iPTH (100+/-18 pg/ml) and low calcitriol levels (10.6+/-4.3 pg/ml) compared with normal rats [N1: 14+/-2.5 pg/ml (P<0.001) and 18.2+/-4.2 pg/ml (P<0.01) respectively]. The pregnancy in CRF rats (CRF2) resulted in normalization of serum iPTH levels (18.2+/-5.41 pg/ml), which was associated with a parallel increase in serum calcitriol (29.4+/-8.0 pg/ml) similar to that in pregnancy of normal rats (N2). Two weeks after delivery the CRF rats (CRF3) once again had high serum iPTH (87+/-17 pg/ml) and low calcitriol levels (9.3+/-1.2 pg/ml), similar to those observed in non-pregnant uraemic rats (CRF1). It is concluded that pregnancy decreases serum iPTH in 5/6 nephrectomized CRF rats most probably by the increased level of calcitriol synthesized by the feto-placental unit.

The identification of secreted heat shock 60 -like protein from rat glial cells and a human neuroblastoma cell line.

The intracellular stress-induced proteins provide protection against toxic insults. Here, a 60,000-Da heat shock 60 (hsp60)-like protein was detected, with five different antibodies, in conditioned media derived from rat cortical astrocytes and a human neuroblastoma cell line. Extracellular neuroblastoma hsp60-like immunoreactivity was increased 3-fold in the presence of the neuropeptide vasoactive intestinal peptide (VIP) and was augmented 2-fold after temperature elevation. Intracellular hsp60 immunoreactivity was reduced 2-3-fold in the presence of VIP; this reduction was attenuated in the presence of brefeldin A, an inhibitor of protein secretion. In contrast, the activity of lactate dehydrogenase (LDH), an intracellular marker, did not change in the presence of VIP. Essentially no extracellular LDH activity was detected, indicating no cellular damage. A novel aspect for stress proteins having extracellular protective roles is suggested.

Low nitric oxide production in patients with chronic renal failure.

BACKGROUND: Rats with chronic renal failure have a low nitric oxide (NO) production and a diminished NO excretion. The supplementation of L-arginine has an inhibitory effect on the progression of renal insufficiency. METHODS: The present study was designed to determine whether chronic renal failure patients have a low NO production. Plasma and urine nitrate (NO3) and nitrite (NO2), stable metabolites of NO, were measured in 83 consecutive patients with chronic renal failure. The 83 chronic renal failure patients were divided into three groups: group 1, mild renal failure (creatinine clearance >60 ml/min/1.73 m2); group 2, moderate renal failure (creatinine clearance >30 <60 ml/min/1.73 m2), and group 3, severe renal failure (creatinine clearance <30 ml/min/1.73 m2). Thirty-three healthy volunteers served as controls. RESULTS: The daily urinary NO excretion was significantly lower in patients with moderate and severe renal failure as compared with those with mild renal failure and normal controls. The lowest values were found in the severe renal failure group. When the 24-hour urinary NO excretion or NO per milligram creatinine and the NO clearance were correlated with the renal function in all patients as a group, these parameters were directly correlated with the creatinine clearance and inversely correlated with the serum creatinine level. The plasma NO concentration was not different between the three chronic renal failure groups, but higher than in the controls. Plasma NO in renal failure patients was not correlated with the creatinine clearance or serum creatinine levels. CONCLUSIONS: Chronic renal failure is a state of NO deficiency. Treatment strategies to increase NO production (L-arginine supplementation or other NO compounds) may prove to be useful in maintaining the renal function and slow the progression of renal disease.