Vitamin D receptor activation in a diabetic-like environment: potential role in the activity of the endothelial pro-inflammatory and thioredoxin pathways.

High blood and tissue concentrations of glucose and advanced glycation end products (AGEs) are thought to play an important role in the development of diabetic vascular complications. Thioredoxin interacting protein (TXNIP) is up-regulated in response to high levels of glucose and is an endogenous inhibitor of thioredoxin (TRX), and may play a contributory role in the occurrence of diabetic-related vascular diseases. Vitamin D inhibits endothelial proliferation and is a cardiovascular protective agent. The present study evaluated the impact of paricalcitol and calcitriol on the endothelial inflammatory and TXNIP pathways in cultured endothelial cells exposed to a diabetic-like environment. Fresh human umbilical vein cord endothelial cells (HUVEC) were treated for 24h with 200 µg/ml AGE-HSA and 250 mg/dl glucose concentrations, with paricalcitol or calcitriol. IL6, IL8, NFκB (p50/p65), receptor of AGE (RAGE), TXNIP, and TRX expressions were evaluated at the levels of mRNA, protein, and TRX activity. Calcitriol and paricalcitol significantly down-regulated the markers involved in the inflammatory responses. Only paricalcitol induced a significant decrease in TXNIP mRNA and protein expressions. Neither paricalcitol nor calcitriol affected TRX reductase activity or TRX mRNA and protein expressions. Our findings indicate that in an endothelial diabetic-like environment, paricalcitol and calcitriol significantly decreased the expression of genes involved in the inflammatory pathway. In this in vitro study, it seems that the TRX antioxidant system was not involved. The different effects found between paricalcitol and calcitriol might reflect the selectivity of vitamin D receptor (VDR) activation.

Calcitriol counteracts endothelial cell pro-inflammatory processes in a chronic kidney disease-like environment.

In advanced chronic kidney disease (CKD), hypocalcemia, high levels of advanced glycation end products (AGEs), and parathyroid hormone (PTH) coexist and are considered to play a role in the development of chronic vasculopathies. The aim of the present study was to evaluate the impact of a CKD-like environment on cultured endothelial cell (EC) functions and to assess the impact of calcitriol on the expression of parameters such as endothelial nitric oxide synthase (eNOS), receptor of AGEs (RAGE), interleukin 6 (IL-6) and nuclear factor kappa B (NFκB). Human umbilical vein cord endothelial cells (HUVEC) were grown in medium containing low Ca(2+) concentration stimulated with AGE-HSA and PTH and treated with calcitriol for additional incubation. mRNA expression was established by reverse transcriptase-PCR, protein expression by Western blot analysis, IL-6 secretion by ELISA, NOS activity by conversion of [(14)C]arginine to [(14)C]citrulline and DNA-binding activity of NFκB-p65 assayed colorimetrically in nuclear extracts. The CKD-like environment characterized by the association of low Ca(2+) and high levels of AGEs and PTH, depressed eNOS system activity and enhanced RAGE and IL-6 expression/secretion. DNA-binding activity of nuclear NFκB-p65 was increased and the expression of IκBα decreased. Addition of calcitriol normalized the expression, secretion and activity of eNOS, RAGE and IL-6. The enhanced NFκB activity was also counteracted probably due to the increased IκBα expression. The effect of CKD-like environment on EC may partly explain the increased vasculopathies in CKD patients, in contrast to calcitriol, which suggests a vascular protective action.

Parathyroid hormone stimulates the endothelial expression of vascular endothelial growth factor.

BACKGROUND: We showed previously that parathyroid hormone (PTH) may stimulate the endothelial expression of pro-atherosclerotic and pro-inflammatory markers. Considering the impact of PTH on vasculature, we decided to evaluate its effect on mRNA and intra-cellular protein expressions of endothelial vascular endothelial growth factor (VEGF) taking into account that VEGF may play a role in the pathogenesis of endothelial dysfunctions. MATERIALS AND METHODS: Human umbilical vein cords endothelial cells (HUVEC) were stimulated for 24 h with 10(-12)-10(-10) mol L(-1) PTH. The VEGF-165 mRNA expression (critical in stimulating endothelial cell proliferation) was evaluated by RT/PCR and the intra-cellular VEGF protein expression by flow cytometry. The pathways by which PTH may have an effect on VEGF expression were also evaluated. RESULTS: PTH (10(-10) mol L(-1)) significantly increased VEGF-165 mRNA expression (P < 0.05). The addition of 50 nmol L(-1) protein kinase C (PKC) and 10 micromol L(-1) protein kinase A (PKA) inhibitors significantly reduced the VEGF-165 mRNA expression (P = 0.01). We also examined whether nitric oxide (NO) may be involved in the PTH-induced stimulation of VEGF-165 expression. Pre-treatment of the cells with 200 micromol L-nitro arginine methyl ester (L-NAME, NO synthase inhibitor) was found to inhibit VEGF-165 mRNA expression (P = 0.006). VEGF protein could not be detected in the medium of HUVEC but it was present in the cell cytoplasm. PTH had no significant effect on cytoplasmatic VEGF protein expression. CONCLUSION: The stimulatory effect of PTH on endothelial VEGF-165 mRNA expression is partly through PKC and PKA pathways and is also NO dependent.

Laparoscopic resorbable mesh fixation. Assessment of an innovative disposable instrument delivering resorbable fixation devices: I-Clip(TM). Final results of a prospective multicentre clinical trial.

BACKGROUND: The aim of this study was to assess the performance and tolerance of an innovative disposable instrument delivering resorbable clips (I-Clip, Sofradim, France) intended for mesh fixation in inguinal, incisional and umbilical hernias of the abdominal wall. The fixation device was designed to be resorbable in 1 year, with reduced trauma to the underlying tissues or the mesh, and with initial mechanical properties equivalent to those of conventional metal staples. METHODS: The study involved 105 patients with inguinal, umbilical or incisional hernias enrolled from 11 centres. Inguinal totally extra peritoneal (TEP) or trans abdomino pre-peritoneal (TAPP) repair was performed with Parietex mesh, incisional or umbilical hernias were treated via the intraperitoneal route with Parietex composite. I-Clips were used for mesh fixation in both indications according to the surgeon's habits. Efficacy was the principal assessment criteria evaluated by two parameters: quality of fixation evaluated subjectively at the time of procedure and recurrence rate according to the follow up at 1, 6 and 12 months. Pain evaluated by the patients using a visual analogue scale (VAS) was the principal secondary assessment criteria. Other tolerance criteria were also evaluated during surgery and follow up. RESULTS: The surgeons' evaluation of the fixation quality was assessed as good to very good in 100% of ventral hernias and good to very good in 85-92% of inguinal hernias. At 1 month, 90% of patients (94/104) were totally pain-free (VAS score: 0) and only ten patients reported low pain (VAS scores: 0.3-3.1). At 1 year, the pain described by those ten patients finally disappeared, 98% of patients (102/104) were totally pain-free. The rate of minor complications not related to the device concerned 5% of the patients at 1 month, which was reduced to 2% at one year and no recurrence or mesh sepsis was observed. CONCLUSIONS: The ease of use of this device, combined with the absence of recurrence related to the investigated device and the good pain-free outcome in this group of patients confirmed the effectiveness and tolerance of the resorbable fixation concept of I-Clip(TM).

Somatostatin treatment attenuates proteinuria and prevents weight loss in NZB/W F1 mice.

Somatostatin, a naturally occurring neuropeptide, is an immunomodulator which inhibits humoral and cell mediated immunity as well as secretion of proinflammatory cytokines. The objective of this study was to examine the effects of a somatostatin analogue on the severity of glomerulonephritis in the female NZB/W F1 murine model of systemic lupus erythematosus (SLE). Twenty female NZB/W F1 mice were treated at 23 weeks of age with 10 mg/kg of the somatostatin analogue Sandostatin- LAR, IM every four weeks. Ten control mice received IM injection of vehicle. Mice were assessed at four-week intervals for weight change, proteinuria, anti-DNA antibodies and splenocyte cytokine profile. The mice were sacrificed at age 34.5 weeks. Kidneys were collected and evaluated by light and immunofluorescence (IF) microscopy. Spleens were collected and splenocyte intracellular cytokines were measured by FACS analysis. In the treatment group significantly less proteinuria was observed four weeks after the second somatostatin analogue injection (dipstik scale: +2.07 +/- 0.95 versus. +3.5 +/- 1.08, P = 0.0002). The treated mice did not lose weight while the control group lost weight over time (P = 0.016). No differences were noted between the groups in anti-DNA antibody titres, cytokine profile or the severity of lupus nephritis as assessed by light and IF microscopy. Somatostatin analogue treatment attenuated proteinuria and prevented weight loss in NZB/W F1 mice, suggesting a possible beneficial effect on renal parameters and systemic manifestations of the disease. Further studies will be needed to assess the value of somatostatin analogue treatment in lupus nephritis, utilizing higher doses, at different stages of the disease, for longer periods.

Intraperitoneal treatment of incisional and umbilical hernias using an innovative composite mesh: four-year results of a prospective multicenter clinical trial.

Intraperitoneal positioning of conventional parietal mesh provides efficient reconstruction but causes visceral adhesion formation in 80-100% of the cases. The purpose of this clinical trial was to assess the performance and tolerance of a new generation of polyester mesh protected by a hydrophilic resorbable film. Eighty patients were included in a prospective multicenter clinical trial. Patients were treated for ventral hernia via an open approach (64%) or laparoscopically (36%). All meshes were implanted in a midline intraperitoneal location. The main objective was to evaluate the anti-adhesive capability of the mesh in relation to the viscera. In order to assess the absence of visceral adhesion objectively, an ultrasound (US) specific examination was initially validated (pre-operative prediction vs. per-operative findings) and then used during the follow-up. The usual clinical parameters were also collected to follow the patients on a period up to 4 years. Pre-operative US prediction vs. per-operative macroscopic findings: sensitivity 79%, overall accuracy 76%, negative predictive value 85%. After 12 months, 86% of the patients were ultrasonically adhesion free. Early post-operative complications were: seroma/hematoma (16%), subcutaneous infection (4%), cutaneous necrosis (1%) and occlusions (outside the mesh) (2.5%). No mortality was reported. Clinically, after 12-month follow-up, no complication related to post-operative adhesions to the mesh was noted: (occlusion 0%, fistula 0%). Late complications were: mesh sepsis (1%), new defects (4%) and recurrence (2.5%). Finally, 56 patients (75.7%) were clinically evaluated with a mean follow-up of 48+/-6 months. One direct recurrence was noted while six patients experienced new defect outside the mesh. No long-term severe complication such as occlusion or enterocutaneous fistula was observed. Based on a mean clinical follow-up of 4 years, the results of this prospective multicenter clinical trial demonstrate the safety and the efficiency of this composite mesh in the intraperitoneal treatment of incisional and umbilical hernia. In particular there was no early or long-term main complication due to the intraperitoneal location of the mesh.

Early endothelial dysfunction following renal mass reduction in rats.

BACKGROUND: Endothelial dysfunction has been previously described in severely hypertensive rats with renal mass reduction (RMR) receiving large dietary Na loads. Because hypertension and Na loading reduce endothelium-dependent vasodilation, the effect of renal failure per se is unclear. METHODS: Responses to acetylcholine in noradrenaline-contracted isolated perfused mesenteric arteries were studied. Vessels were obtained from RMR rats kept on a normal diet, 3 and 10 days after surgery, and the results were compared with those from sham-operated rats (SN). The role of three putative mediators of endothelium-dependent vasodilation was assessed using: L-NAME (10(-4) mol L(-1)); indomethacin (INDO, 10(-5) mol L(-1)); and a mixture of charybdotoxin and apamin (C/A, both 10(-7) mol L(-1)), inhibitors of Ca-activated K-channels to mediate the effects of endothelium-derived hyperpolarizing factor (EDHF). RESULTS: Response to acetylcholine but not that to nitroprusside (endothelium-independent) was decreased in RMR. L-NAME reduced further acetylcholine relaxations in SN but not in RMR. By contrary, INDO decreased acetylcholine vasodilation in RMR but had no effect in SN. C/A had similar effects in the SN and RMR rats. The levels of 6-keto prostaglandin F1alpha were elevated in the urine of the RMR rats and were perfusate from the RMR vessels. CONCLUSION: Endothelial dysfunction occurs early after RMR, even when systolic blood pressure is only minimally elevated and Na intake is normal. This alteration may be because of decreased availability of nitric oxide, partially compensated by increased prostacyclin production.

Effect of methyldopa on renal function in rats with L-NAME-induced hypertension in pregnancy.

BACKGROUND: Pregnancy-induced hypertension is characterized by an increased sympathetic activity and probably by a decreased synthesis/activity of nitric oxide. The aim of the present study is to evaluate whether the beneficial action of the sympathetic antagonist methyldopa (a first-choice hypotensive agent in the treatment of PIH) may be associated to changes in nitric-oxide synthesis. METHODS: Forty pregnant Wistar rats received L-NAME (NO synthase inhibitor, 9-10 mg/kg/day) from mid-pregnancy (day 11) through to term. Some rats were treated with daltroban (TxA receptor antagonist, 60 mg/kg/day), diltiazem (calcium channel blocker, 30 mg/kg/day), methyldopa (central adrenergic antagonist, 400 mg/kg/day) or L-arginine (260 mg/kg/day) from mid-pregnancy. The effect of the different treatments on systolic blood pressure (SBP), creatinine clearance (CCR), urine protein excretion (UP) and urinary nitrate excretion (UNO(3), representing urine NO metabolite) were evaluated and the results compared with those found in normal pregnancy. Normal pregnant rats receiving similar treatment were used as controls. RESULTS: In normal pregnant (P) rats, SBP values decreased from 94 +/- 2 to 83 +/- 3 mm Hg at the end of pregnancy (p < 0.01) and CCR augmented significantly. Drug treatment had no significant effect. In NAME-treated rats, at the same period, the SBP augmented from 92 +/- 1 to 129 +/- 1.8 mm Hg (p < 0.01). At the end of pregnancy, NAME rats had significantly lower CCR values and higher UP excretion when compared with P rats. UNO(3) increased significantly in P and in P rats treated with methyldopa. As expected, in NAME rats UNO(3) excretion was significantly reduced. Treatment with methyldopa normalized SBP, improved CCR and proteinuria and was associated with an increase in UNO(3). Similar results were obtained with L-arginine treatment. Diltiazem lowered SBP significantly but had no effect on renal function or UNO(3) and daltroban had no effect. CONCLUSION: The increased UNO(3) found in NAME rats treated with methyldopa suggests that the vasoconstriction secondary to chronic NO inhibition may be partially related to an increased sympathetic activity. The efficient action of the sympathetic antagonist methyldopa may be due not only to its antihypertensive effects but also by its stimulating effect on NO synthesis leading also to an improvement of renal function.

Laparoscopic gastric banding with Lap-Band for morbid obesity: two-step technique may improve outcome.

BACKGROUND: Laparoscopic placement of an adjustable gastric band is an attractive alternative for patients who can benefit from a restrictive bariatric procedure. Creation of the retrogastric tunnel (RGT) may, however, be a considerable challenge early in the surgeon's learning curve. Recent reports described up to 10% band slippage and occasional gastric perforation associated with RGT. The two-step (TS) technique involves a crural dissection towards the angle of His through a gastrohepatic ligament approach. It facilitates passage of the band's tubing posteriorly with no wide posterior gastric wall dissection. PATIENTS AND METHODS: Prospective data were registered for the 109 patients (92 females, 17 males) who underwent laparoscopic adjustable gastric banding from December 1998 to May 2000. In 11 patients the standard RGT approach was used, and in 98, the TS technique. The two groups were demographically similar. Mean age was 37 years (18-59); mean preoperative weight was 120 kg (90-165). RESULTS: All procedures were completed laparoscopically. The mean operative time was 59 minutes (31-150) and the mean hospital stay 1.2 days (1-5). Complications in the TS group were gastric wall hematoma in one patient, 3 days of intubation postoperatively in one patient, damage to a band demonstrated in a postoperative contrast study in one patient, and a port-site hernia in one patient. There was no band slippage in the TS group. Among the 11 patients undergoing RGT, there was band slippage in three (27%), immediately postoperatively in one and after 3 and 11 months in the other two. In a mean follow-up of 7 months (1-18), similar weight loss was found in both groups. The mean BMI decreased from 44 kg/m2 (36-61) preoperatively to 40, 38, 36, 34 kg/m2 at 1, 3, 6 and 9 months respectively. 52 patients required band adjustment; of these, 12 required two adjustments. CONCLUSION: Our experience with both the RGT and TS techniques indicates that the latter may offer better results, particularly in the early experience period. It is recommended that in their initial experience with the adjustable band, surgeons should become familiar with this approach.

Chronic exogenous hyperinsulinaemia-induced hypertension in pregnant rats: effect of chronic treatment with l-arginine.

Recent studies have shown that maternal hyperinsulinaemia is a risk factor for the development of hypertension in pregnancy. Experimentally, pregnant rats with chronic exogenously induced hyperinsulinaemia (P-INS rats) have increased blood pressure at the end of gestation. This is associated with a blunted elevation of the excretion of the urinary metabolites of nitrate (UNO(x)). In the present study, we aimed to evaluate the mechanism(s) of the increase in blood pressure in this model. Four groups were studied: normal pregnant rats (P rats), P-INS rats, P-INS rats treated with L-arginine (2 g/l in the drinking water) (L-ARG rats) and hyperinsulinaemic virgin rats (V-INS rats). Systolic blood pressure (SBP), UNO(x) excretion (on ingestion of a controlled low-nitrate diet), urine noradrenaline (norepinephrine) and plasma endothelin levels were evaluated. Rats were killed on day 22 of pregnancy. Five P-INS rats were not killed at this time, in order to measure SBP 30 and 60 days after delivery. Fetal number and fetal body weight were evaluated. At the end of pregnancy, a 10+/-3% increase in SBP was found in P-INS rats, contrasting with a fall of -15+/-4% in P rats (P<0.01). In the L-ARG group at the end of pregnancy, SBP values had fallen by -14+/-2%, to values comparable with those of P rats. The increase in UNO(x) excretion was 175+/-38% in P rats, 106+/-12% in L-ARG rats and 41+/-8% in P-INS rats (P<0.01 compared with P and L-ARG groups). No differences were found in the urinary excretion of noradrenaline or in the plasma levels of endothelin-1 between the pregnant groups. Fetal number was similar in all groups, but fetal body weight was lower for P-INS rats compared with P and L-ARG rats. Thus the blood pressure response to L-arginine strongly suggests that a decrease in NO availability may be the main pathogenic mechanism involved in the development of hypertension in this model.

Low molecular weight heparin reduces proteinuria and modulates glomerular TNF-alpha production in the early phase of adriamycin nephropathy.

BACKGROUND/AIM: Heparin has been shown to be renoprotective in a number of experimental nephropathies. The inflammatory component in the early phase of Adriamycin (ADR) induced nephropathy has been established. A microdose of low molecular weight heparin (Fragmin; F) has been noted to exert immunomodulatory effects independent of its anticoagulant activity. We assessed the effects of microdoses of F on daily proteinuria and glomerular production of tumor necrosis factor alpha (TNF-alpha) and prostaglandins 8 and 15 days after induction of ADR nephropathy. METHODS: Following intravenous injection of ADR (7 mg/kg) to Wistar rats weighing 200 +/- 20 g, F 20 microg/day/rat s.c. was administered for 8 and 15 days (groups F8 and F15). The respective control groups (C8 and C15) received normal saline subcutaneously. Proteinuria, serum albumin, and creatinine clearance were evaluated on days 8 and 15. The production of TNF-alpha and prostaglandins from glomerular supernatants was measured by radioimmunoassay on days 8 and 15. RESULTS: F significantly reduced proteinuria (mg/day) on day 8: 13.6 +/- 1.2 in F8 versus 40.3 +/- 2.7 in C8 (p = 0.008). The glomerular production of TNF-alpha (pi/ml) was significantly lower on day 8 in rats treated with F: 356 +/- 33 in F8 versus 764 +/- 81 in C8 (p = 0.006). A decrease in the prostaglandin E2/thromboxane B2 ratio was noted in the F group between 8 and 15 days (1.1 in F8 vs. 0.9 in F15, p = 0.005) which principally reflects an increase of thromboxane B2. The antiproteinuric effect of F shown after 8 days was no longer present after 15 days (354 +/- 91 mg/day in F15 vs. 499 +/- 69 mg/day in C15, p = 0.33). The same trend was seen for the glomerular production of TNF-alpha. Light microscopy and immunohistochemistry for interstitial and glomerular macrophages were negative. CONCLUSION: The lowering effect of microdoses of F on the proteinuria seen during the early phase of ADR nephropathy may be mediated by a decreased production of glomerular TNF-alpha, supporting the anti-inflammatory action of low molecular weight heparin.

A multicentric comparison of transabdominal versus totally extraperitoneal laparoscopic hernia repair using PARIETEX meshes.

The authors report a series of 1972 inguinal hernias treated between 1993 and 1997 by the insertion of a PARIETEX mesh via either a transabdominal-preperitoneal (TAPP) (1,290 procedures) or a totally extraperitoneal TEP approach (682 procedures). Pain scores were equivalent in both groups, while the hospital stay and time to return to normal activity was lower in the TEP group than in the TAPP group (p<0.001). In both groups, the average incidence of the total reported events (complications) was around 10% with no statistical difference. This ratio seemed to compare favorably to previously published reports. Chronic pain was extremely rare (0.6% and 0.7% in the TAPP and TEP groups, respectively). Whatever the approach was, sepsis was also very rare (1/1,526 laparoscopic procedures). These findings illustrate the local tolerance of the mesh. Recurrence rates were below 1% with no statistical difference between groups. This retrospective study demonstrates the clinically apparent local tolerance of this type of mesh. Prospective and long-term clinical results will be necessary to demonstrate that the optimized short-term tolerance of PARIETEX mesh will influence the long term functional results.

[Time off of work after inguinal hernia repair. Results of a multicenter prospective study]. / Arrêt de travail après cure de hernie inguinale. Résultats d'une étude prospective multicentrique.

A multicentre prospective study was conducted to evaluate the effective duration of time off work following inguinal hernia repair. From 1st October to 30 November 1997, 14 surgeons repaired 459 hernias in 359 patients, corresponding to 28.8% of salaried workers, 10.9% self-employed and 4.8% civil servants. 46% of patients were retired. Only 6.9% of patients were treated by reconstruction of the inguinal floor without mesh, 59.6% were operated by laparoscopy and a conventional prosthesis repair was performed in 33.2%. There were 0.6% of complications or modifications of the postoperative course. The mean effective time off work was 17.5 days after unilateral repair and 24.7 days after bilateral repair. For unilateral repairs, no significant difference was observed between occupational groups in terms of effective time off work, in the absence of complications. In contrast, patients of these occupational groups presented a shorter time off work following an uncomplicated TAPP repair than after plug-Lichtenstein repair. In the group of salaried workers, a significant difference was observed between patients undergoing TAPP or TEP repair and those undergoing plug-Lichtenstein repair.

Altered vascular reactivity following partial nephrectomy in the rat: a possible mechanism of the blood-pressure-lowering effect of heparin.

BACKGROUND: This study was designed to assess whether the antihypertensive effect of heparin in rats after renal mass reduction (RMR) is related to changes in nitric oxide activity, and to study in vitro the altered behaviour of resistance-sized arteries induced by chronic administration of heparin. METHODS: Male Wistar rats were assigned to one of two experimental protocols. In the first protocol, RMR rats received heparin (250 units/day s.c.) and tail systolic blood pressure (SBP) was measured weekly for 4 weeks. In a subgroup, urinary nitrate excretion (UNO3) and in vitro vascular reactivity of isolated perfused mesenteric arterial beds were measured 2 weeks after RMR. The second protocol assessed whether inhibition of NO synthesis with L-NAME (70 mg/l added to the drinking water) prevents the blood-pressure-lowering effect of heparin. RESULTS: In untreated RMR rats SBP increased from 111+/-3 mmHg to 127+/-5 mmHg at 2 weeks and 139+/-5 mmHg at 4 weeks. In contrast, in RMR rats treated with heparin, SBP was 114 +/-3 mmHg at 2 weeks and 115+/-4 mmHg at 4 weeks (P<0.05 for both). Treatment with L-NAME increased SBP both in untreated and heparin-treated RMR groups. Two weeks after nephrectomy daily urinary nitrate increased significantly more in RMR rats treated with heparin than in untreated RMR rats (22+/-2 vs 14.2+/-2.3 micromol/day, P<0.05). In vitro studies performed at 2 weeks showed that vessels of untreated RMR rats had a blunted vasodilator response to acetylcholine that was restored to levels similar to that of controls in the heparin-treated group. CONCLUSIONS: These results suggest that, in rats after renal ablation, heparin may exert its antihypertensive effect, at least in part, by affecting the altered behaviour of resistance vessels during the development phase of hypertension. Increased NO production may contribute to this effect.

Nitric oxide and vascular reactivity in pregnant rats with adriamycin nephropathy.

1. In previous studies we have shown that, after the administration of adriamycin, hypertension developed in rats who became pregnant (adriamycin-pregnant rats), whereas virgin animals remained normotensive. Subsequently, we showed that this hypertension was prevented by administration of L-arginine, suggesting that deficient synthesis of nitric oxide may be pathogenetic in this model. 2. To further assess the role of nitric oxide in this model, we measured mean arterial blood pressure after administration of L-arginine to adriamycin-pregnant rats or of NG-nitro-L-arginine-methyl ester (L-NAME) to normal pregnant rats. In other experiments, we assessed the response of isolated perfused arterial mesenteric vessels, precontracted with noradrenaline, to acetylcholine, L-arginine or L-NAME. 3. Blood pressure was decreased in normal pregnant rats, whereas it was elevated in adriamycin-pregnant rats. L-NAME treatment increased blood pressure in normal pregnant rats and L-arginine decreased it in adriamycin-pregnant rats. 4. Mesenteric vessels of adriamycin-pregnant rats exhibited an exaggerated vasoconstrictory response to noradrenaline, when compared with the blunted response observed in normal pregnancy. The addition of L-NAME in vitro induced a further contraction, significantly greater in normal pregnant rats. The vasodilatory response to acetylcholine and L-arginine was greater in vessels from adriamycin-pregnant rats. In contrast, responses to either nitroprusside or diazoxide were similar in all groups. 5. The results suggest a state of reduced nitric oxide synthesis in rats with adriamycin nephropathy, leading to vascular maladaption and hypertension in pregnancy.