The role of K+ channels in the nitric oxide-independent renal vasodilator effect of acetylcholine (Ach) was examined to address the hypothesis that the mechanism underlying this response was different from that of bradykinin, because an earlier study indicated the possibility of different mediators. We used the rat isolated, perfused kidney that was constricted with phenylephrine and treated wi...

The effects of intravenous administration of sodium nitroprusside to a donor dog on cardiac pacemaker activity and contractility were investigated in a cross-circulated dog heart preparation; i.e., the isolated atrial muscle was perfused with blood from a pentobarbital anesthetized donor dog. Intravenous administration of nitroprusside (1-10 micrograms/Kg) caused a hypotension with tachycardia,...

Animal studies suggest that some angiotensin converting enzyme inhibitors augment endothelium-dependent vasorelaxation. We aimed to determine if captopril augments endothelium-dependent vasodilation in middle-aged hypertensive patients. By using strain-gauge plethysmography, forearm vasodilation evoked with intra-arterial acetylcholine (4, 8, 16, and 24 micrograms/min) or nitroprusside (0.2, 0....

To elucidate the molecular mechanism of the vascular action of atrial natriuretic factor (ANF), we investigated the effects of synthetic ANF and sodium nitroprusside on the levels of intracellular cyclic nucleotides and prostacyclin (measured as its stable metabolite 6-keto-prostaglandin F1 alpha) in cultured vascular smooth muscle cells from rat mesenteric artery and, in some experiments, from...

In an open-label study, we compared the efficacy and safety of intravenous infusion of fenoldopam mesylate with that of sodium nitroprusside in patients with severe hypertension or in hypertensive crisis. Both antihypertensive medications were infused at a maximal dose increment of 0.2 microgram/kg/min (fenoldopam) and 1 microgram/kg/min (nitroprusside), with a maximal infusion rate of 1.5 micr...

Vascular responsiveness to nitroprusside and to norepinephrine was examined in two different preparations from DOCA hypertensive and normotensive control Sprague-Dawley rats. The blood-perfused renal vasculatures of DOCA hypertensive rats were significantly more sensitive than those of normotensive controls to the vasodilator action of low doses of nitroprusside. At high doses, responses in DOC...

Several recently reported deaths following the use of sodium nitroprusside have been attributed to the accumulation of the nitroprusside metabolite, cyanide. In this study, brief nitroprusside infusions (mean = 36 minutes) were administered in currently recommended doses during intracranial surgery. The peak blood cyanide following the infusions was 65.2 +/- 17.5 microgram per cent (mean +/- SE...

Dose-response curves to topically applied acetylcholine, bradykinin, and nitroprusside were obtained by intravital microscopy in arcading arterioles of the spinotrapezius muscle of control (n = 9) and one-kidney, one clip hypertensive (1K1C) rats (n = 11) of 4 weeks' duration before and during superfusion with the specific inhibitor of nitric oxide formation NG-monomethyl L-arginine (LNMMA) (10...

BACKGROUND The regulation of renal sympathetic activity in the setting of heart failure is largely unexplored. We used the norepinephrine spillover method to address the hypothesis that baroreflex control of renal sympathetic activity is blunted in heart failure. METHODS AND RESULTS Twenty-two patients were studied, 11 in a group with heart failure and 11 in a group with normal ventricular fu...