Guanylate cyclase activators influence reactivity of human mesenteric superior arteries retrieved and preserved in the same conditions as transplanted kidneys.

INTRODUCTION: This study sought to investigate the mechanisms of relaxation induced by the (nitric oxide (NO)-independent soluble guanylyl cyclase (sGC) stimulators 3-[5'-hydroxymethyl-2'-furyl]-1-benzylindazole (YC-1) in human mesenteric arteries relaxed and precontracted with 1 micromol/L 5-hydroxytryptamine (serotonin). MATERIAL AND METHODS: Human mesenteric arteries obtained during kidney retrieval were preserved in the same conditions as transplanted kidneys. All experiments were performed after reperfusion with Krebs buffer in 37 degrees C and 100% oxygen exposure. RESULTS: In endothelium-intact rings, YC-1 (0.001 to 30 mmol/L) caused concentration-dependent relaxation (pEC(50): 6.59 +/- 0.12), which shifted to the right in endothelium-denuded rings. The sGC inhibitor 1H- [1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ 10 mmol/L) partially attenuated the maximal responses to YC-1 (E(max) = 51.30% +/- 3.70%; n = 6) and displaced its curve to the right in intact and denuded vessels. Both, the NO synthesis inhibitor N-nitro-L-arginine methyl ester (100 mmol/L) and the NO scavenger carboxy-2-[4-carboxyphenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (100 mmol/L) significantly reduced YC-1 relaxation. The sodium pump inhibitor ouabain (1 micromol/L) produced a greater decrease in the vasodilator response of YC-1 (E(max) = 18.7% +/- 4.55%; n = 9). ODQ (10 micromol/L) plus 1 mumol/L ouabain abolished the relaxant response of YC-1 (E(max) = 9.4% +/- 2.94%, n = 9). CONCLUSIONS: This study demonstrated that sodium pump stimulation by YC-1 as an additional mechanism of sGC activation independent of cGMP relaxed human mesenteric artery, including blockade of Ca(2+) influx. Furthermore, this study suggested an ability of NO to mediate relaxation of resistance-like arteries through the activation of soluble guanylate cyclase and K(+) channels.

The analysis of dehydroepiandrosterone sulphate concentration in elderly age women depending on coexisting disease states.

PURPOSE: The aim of the study was evaluation of dehydroepiandrosterone sulphate (DHEA-S) serum concentration in elderly women and determining interdependence between DHEA-S levels and occurrence of diseases typical for this period of life. MATERIAL AND METHODS: The study was conducted on 103 elderly women (mean age 70.7 +/- 7.3 years). The control group consisted of 25 young and healthy women (mean age 33.5 +/- 1.7 years). The elderly patients were fully functional, well nourished, and only periodically required medical care due to chronic illnesses such as coronary heart disease, arterial hypertension, type 2 diabetes, osteoporosis, depression. DHEA-S serum concentration was determined by Spectria DHEA(S) RIA radioimmunological kit. Statistically significantly important decrease of DHEA-S serum concentration was determined in elderly women compared with the control group. RESULTS: Mean blood serum DHEA-S concentration in elderly group was significantly lower compared to controls. Mean blood serum DHEA-S concentration was statistically significantly lower in the group of patients suffering from coronary heart disease, osteoporosis, and depression. Statistically significantly lower DHEA-S concentration was observed in patients with benign disorders of cognitive functions and depression compared with patients with correct MMSE and GDS results. CONCLUSIONS: In elderly women DHEA-S concentration can turn out to be useful aging biomarker. Concentration of this hormone significantly decreases together with age, especially with coexisting diseases typical for this period of life.

Nitric oxide and thromboxane A2 modulate pulmonary pressure after ischemia and intestinal reperfusion.

INTRODUCTION: Nitric oxide (NO) and thromboxane A(2) (TxA(2)) are paracrine substances that likely contribute to IR-induced lung injury. This study examined the hypothesis that pulmonary vasoconstriction during ischemia is induced by NO synthesis and ischemia/reperfusion (IR)-induced TxA(2). METHODS: Wistar rats underwent 30 or 60 minute of intestinal ischemia with 60 minute of IR in situ. Sham-operated animals (Sham) served as the controls. After ischemia and IR or Sham, the pulmonary vessels were cannulated to perfuse the lungs with Krebs buffer in vitro. Pulmonary arterial (Ppa) and venous (Ppv) pressures were measured to calculate vascular resistance (Rt). RESULTS: After baseline measurements, the nonselective inhibitor (N(omega)-nitro-L-arginine methyl ester), the selective nNOS inhibitor 1-(2-trifluoromethylphenyl) imidazole (TRIM), TxA(2) synthase inhibitor imidazole or TxA(2)-receptor antagonist SQ-29,548 was added to the perfusate prior to measurements of Ppa, Ppv, and Ppc. The Rt was 73% greater in the injured group (P = .01). Pc of in the IR lungs was about twice that of controls (7.2 +/- 0.71 vs 2.43 +/- 0.36 mm Hg, respectively; P < .01). The nNOS inhibitor TRIM, imidazole, or SQ-29,548 reduced Rt by 45%, 33%, and 26%, respectively. IR-induced increases in Pc were reduced by addition of 500 mug/mL imidazole but not by lower doses of imidazole or SQ-29,548. CONCLUSIONS: IR-induced pulmonary dysfunction is caused by increased vascular resistance and increased perfusion pressure. These changes are, at least in part, due to the ongoing release of TxA(2). Administration of 8Br-cGMP protected against TxA(2)-induced vasoconstriction.

Effect of vitamin E and vitamin C supplementation on antioxidative state and renal glomerular basement membrane thickness in diabetic kidney.

The aim of this study was to analyze the effect of vitamins C and E on malondialdehyde (MDA) content and activities of key antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) as well as glomerular basement membrane (GBM) thickness in streptozotocin-induced diabetic kidney in rats. Wistar male rats were divided into following groups (12 rats each): the control, diabetic rats, diabetic rats whose drinking water was supplemented with vitamin C in a dose of 1.0 g/l or diet was supplemented with 200 mg of vitamin E/100 g fodder. Body weight, blood glucose and HbA1C levels and 24-hour urinary albumin excretion (UAE) were studied every week (0-12 weeks). After 6 and 12 weeks, MDA content and activities of SOD, CAT and GSH-Px were measured in the kidney homogenate supernatants. Electron micrographs of glomeruli were scanned and morphometric investigations were performed by means of computer image analysis system to compare GBM thickness. The blood glucose and HbA1C concentrations and UAE in diabetic rats were significantly higher than in the control group. An increase in the MDA level and decrease in the SOD, CAT and GSH-Px activities in the kidney of diabetic rats were observed after 6 and 12 weeks of experiment. Administration of vitamins C and E did not affect body weight, blood glucose and HbA1C levels. Both vitamin C and vitamin E decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in the kidneys of diabetic rats as well as reduced UAE, decreased kidney weight and GBM thickness. The results indicate the potential utility of antioxidant vitamins in the protection against the development of diabetic nephropathy.

The effect of verapamil on the antioxidant defence system in diabetic kidney.

BACKGROUND: The aim of this study was to examine the effect of verapamil (VP) on lipid peroxidation and activities of key antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px); as well as on glomerular basement membrane (GBM) thickness in streptozotocin-induced diabetic kidney in rats. METHODS: Wistar male rats were divided into three groups, 12 rats each: the control (C), diabetic rats (DR), and DR receiving VP, 7 mg/kg body weight in drinking water (DR + VP). Blood glucose (BG) and HbA(1c) levels, 24-h urinary albumin excretion (UAE) and body weight (BW) were measured every week (0-12 weeks). After 6 and 12 weeks, the animals were sacrificed and malondialdehyde (MDA) content and activities of SOD, CAT and GSH-Px were determined in the kidney homogenate supernatants. Electron micrographs of the glomeruli were scanned and morphometric investigations were performed by means of a computer image analysis system to compare the glomerular basement basal membrane (GBM) thickness. RESULTS: The levels of BG, HbA(1c) and UAE in DR were significantly higher than in the C group. A progressive increase in the MDA level and a decrease in the SOD, CAT and GSH-Px activities in the kidney of DR were observed after 6 and 12 weeks. VP administration did not affect BW changes, BG and HbA(1c) levels in DR. VP decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in the kidneys of DR as well as decreased kidney weight, GBM thickness and albuminuria in DR. CONCLUSIONS: These results confirm the role of oxidative stress in the development of diabetic nephropathy and point to the possible antioxidative mechanism of the nephroprotective action of VP.

Pharmacometric analysis of alpha1-adrenoceptor function in rat tail artery pretreated with lipopolysaccharides.

The inhibitory effect of lipopolysaccharides (LPS) on contraction evoked by alpha-adrenergic stimulation is quite well-known, but molecular mechanism of this inhibition is unclear. In the present study, an interaction between alpha-adrenoceptor response and LPS in rat tail artery was investigated using chemical stimulation. In the presence of LPS noradrenaline and phenylephrine, concentration-response curves were shifted to the right with a change in maximal responses. The K(A) and K(B) values calculated in the presence and absence of LPS did not differ significantly. The results strongly suggest that LPS did not change the affinity of alpha-adrenoceptors. Changes in the plot showing relationship between agonist-evoked responses and receptor occupancy in the presence of LPS and reduction of K(A)/ED50 value suggest reduction of alpha-adrenoceptor reserve. In the experiments performed on arteries without endothelium, the inhibitory effect of LPS was still present. In the presence of atropine, antazoline and indomethacin, the reduction of alpha-adrenoceptor reserve was noted, but in the presence of N-omega-nitro-L-arginine methyl ester (L-NAME), the inhibitory effect of LPS was not significant. Moreover, in LPS-pretreated arteries, in the presence of L-NAME, the increase in the receptor reserve was observed. It suggests that inhibitory effect of LPS is partially reversible. The results strongly indicate that in early endotoxemia, main inhibitory effect of LPS is connected with releasing nitric oxide and decreasing coupling between alpha1-adrenoceptor and signal induction.

[Studies of methotrexate pharmacokinetics in children with neoplasms of the hematopoietic system after administration of different doses of the drug]. / Badania farmakokinetyki metotreksatu u dzieci z nowotworami ukladu krwiotwórczego po podaniu róznych dawek tego leku.

Concentration of MTX was determined in the serum after the infusion of MTX in a dose of 0.5 g/m2, 1.0 g/m2 and 5.0 g/m2 to 24 children with ALL/NHL. The mean value of steady-state concentrations of MTX was two-fold greater after the infusion of a dose of 1.0 g/m2 and ten-fold greater after the infusion of a dose 5.0 g/m2 than at dose 0.5 g/m2. Great inpatient and interpatient variations of serum MTX concentrations were observed. Pharmacokinetic analysis of the data revealed biphasic model of the elimination. Statistically significant differences were found between the half-life MTX values (ti/2 alpha) in the first postinfusion day: the higher the dose, the shorter ti/2 was observed. The ti/2 of MTX during the second postinfusion day was significantly longer than that of the first day after infusion, but values for the higher doses were not significantly shorter than those for 0.5 g/m2. Systemic clearance (Cl) of MTX showed inpatient and interpatient variations of the values. However, no statistically significant difference was found between Cl values at doses of 0.5 g/m2, 1.0 g/m2 and 5.0 g/m2.

[Cerebrospinal fluid methotrexate level in children treated with medium-high and high doses of the drug]. / Stezenie metotreksatu w plynie mózgowo-rdzeniowym u dzieci leczonych srednio duzymi i duzymi dawkami leku.

Concentrations of MTX were determined in the cerebrospinal fluid (csf) and serum after intravenous infusion of MTX at intermediate dose (0.5-1.0 g/m2) and at high dose (5.0 g/m2) to 20 children (33 infusions) with ALL/NHL. The cytotoxic concentrations of MTX in csf (> 1.0 microM/l) were reached in half of the cases after the infusion of MTX at intermediate dose and in all patients after the infusion of 5.0 g/m2. Great inpatient and interpatient variations of MTX concentrations in csf were observed. No statistically significant difference was found between mean systemic clearance of MTX in patients with MTXcsf concentrations > 1.0 microM/l and < 1.0 microM/l after infusion of MTX at intermediate dose.

Furosemide antagonizes the contractile response to noradrenaline on isolated rat tail artery.

To determine the effect of furosemide (FUR) on the noradrenaline (NA) contraction of arteries, experiments were performed on isolated rat tail arteries according to Nicholas. FUR (300 mumol/l, 3 mmol/l) as well as Ca2+ transport system inhibitor, verapamil (VER), decreased the NA contractile force and FUR (3 mmol/l) antagonized the effect of VER (10 and 100 nmol/l). Calculated dose ratios according to Stephenson indicated that FUR and VER compete not only with NA but with each other. FUR decreased Ca2+ concentration in rat arteries studied in vivo by atomic absorption spectrophotometric method as well. It could be assumed that FUR depresses the sensitivity to NA and antagonizes NA induced contraction of arteries acting on transmembrane Ca2+ transport system.