Nitric oxide synthesis does not affect depressor responses induced by endothelin-1 into the superior colliculus of rats.
A microinjection of endothelin-1 (ET-1; 10 pmol) into the superior colliculus (SC) of anaesthetised rats caused a decrease in blood pressure. Microinjection into the same nucleus of Nomega-nitro-L-arginine methyl ester (L-NAME; 0.1, 0.5, 1 micromol), an L-arginine analogue and a potent inhibitor of nitric oxide (NO) synthase, increased the basal mean arterial blood pressure. Treatment of SC with L-NAME (1 micromol) did not affect the depressor response induced by injection of ET-1 (10 pmol), into the SC, at the peak of the pressor response to L-NAME. In addition, L-arginine L-ARG) (1 micromol), the substrate for NO synthase, microinjected into the superior colliculus prior to ET-1 did not significantly increase the depressor response to ET-1. These findings, therefore, suggest that within the SC the nitric oxide synthesis does not affect depressor responses induced by ET-1.(c) 1998 The Italian Pharmacological Society
D'Amico
M
M
Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery, 2nd University of Naples, Via Costantinopoli 16, Naples, 80138, Italy.
Di Filippo
C
C
Rossi
F
F
Rossi
F
F
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013477:Superior Colliculi / Q000187:drug effects* / Q000502:physiology
D019332:Endothelin-1; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester