Influence of HOE 140, A Bradykinin Receptor Antagonist, in the Isolated Mesenteric Vascular Bed of the Rat.

The inhibitory effects of HOE 140 (D-Arg-[Hyp(3),Thi(5),D-Tic(7), Oic(8)]bradykinin), a novel bradykinin B(2)-receptor antagonist, on mesenteric vascular bed vasodilator responses to bradykinin (BK) were investigated under constant-flow conditions in the isolated blood-perfused rat mesenteric vascular bed. During baseline conditions, injections of BK produced dose-related decreases in mesenteric arterial perfusion pressure which were reproducible with respect to time. HOE 140, in a dose of 50 &mgr;g/kg intravenously, decreased vasodilator responses to BK but had no significant effect on mesenteric vasodilator responses to albuterol, acetylcholine, levcromakalim, or to nitroglycerin.

Comparative Effects of N(omega)-L-Nitro-L-Arginine Methyl Ester and N(omega)-L-Nitro-L-Arginine Benzyl Ester in the Mesenteric Circulation of the Rat.

Comparative effects of the nitric oxide (NO) synthase inhibitors, N(omega)-L-nitro-L-arginine methyl ester, and N(omega)-L-nitro-L-arginine benzyl ester on baseline arterial tone and on vasodilator responses to acetylcholine, isoproterenol, prostaglandin E(1), histamine, and nitroglycerin were investigated in the isolated mesenteric vascular bed of the rat. Under constant-flow conditions, intra-arterial (IA) injections of acetylcholine (100 ng--1 &mgr;g), isoproterenol (100 ng--1 &mgr;g), prostaglandin E(1) (0.3--3 &mgr;g), histamine (300 ng--3 &mgr;g), and nitroglycerin (100 ng--1 &mgr;g) caused dose-related decreases in mesenteric arterial perfusion pressure and decreases in systemic arterial pressure.

Nomega-Nitro-L-Arginine Benzyl Ester Enhances Pulmonary Vasopressor Responses to Hypoxia and to Angiotensin II.

The effects of Nomega-nitro-L-arginine benzyl ester (L-NABE), an inhibitor of nitric oxide (NO) synthase, were investigated on pulmonary arterial responses during baseline or low tone conditions and during elevated tone conditions induced by ventilatory hypoxia or by AII in the isolated blood-perfused rat lung. We also tested the influence L-NABE on the vasodilator responses to acetylcholine (ACh) and nitroglycerin (GTN) during elevated pulmonary arterial tone conditions. Under baseline conditions, L-NABE in doses of 10--1000 &mgr;g, induced small increases in pulmonary arterial perfusion pressure that were significant for the higher doses studied.

Hemodynamic Responses to Papaverine: Do Nitric Oxide, Cyclic GMP, or Calcium Mediate the Vasodilation?

Papaverine is a commonly used vasodilator of the internal mammary artery in cardiac surgery. The effects of papaverine with and without N(omega)-L-arginine methyl ester (L -NAME) (a nitric oxide production inhibitor) and/or zaprinast (a cyclic GMP inhibitor) or verapamil (calcium channel antagonist) on systemic vascular resistance in vivo have not been well documented. This study examines the hemodynamic responses to papaverine and attempts to identify the role of nitric oxide, cyclic guanosine monophosphate (GMP), and calcium in the vasodilation.

The Effect of Cromakalim on the Hindlimb Vascular Bed of the Male Rat: Do Glybenclamide and/or Nitric Oxide Modulate the Vasodilation?

Cromakalim, a benzopyran derivative, is a member of a novel class of antihypertensive agents that increase membrane K(+) conductance through ATP-sensitive K(+) channels. The effects of glybenclamide and N(omega)-L-arginine methyl ester (L-NAME), a specific inhibitor of nitric oxide synthesis from L-arginine were investigated on the vasodilator response to cromakalim in the hindlimb vascular bed in the male rat, as well as the combination glybenclamide and L-NAME. Thirty male Sprague--Dawley rats (350--450 g) were studied.