Role of nitric oxide from the endothelium on the neurogenic contractile responses of rabbit pulmonary artery.
The effects of L-NG-nitro arginine (L-NO2Arg), a stereospecific inhibitor of nitric oxide formation, on the responsiveness of rabbit pulmonary artery to transmural electrical stimulation were studied. The contractile response evoked by electrical stimulation at 4 Hz was abolished by tetrodotoxin (10(-7) M) and depressed to approximately 10% by bunazosin (10(-6) M), an alpha 1-antagonist. Pretreatment with L-NO2Arg (10(-5) M) significantly potentiated the response to electrical stimulation without changing the resting tension. D-NO2Arg (10(-5) M) did not show such a potentiating action. In endothelium-denuded arteries, L-NO2Arg did not potentiate the response to electrical stimulation. The effect of L-NO2Arg on endogenous noradrenaline release in response to electrical stimulation was also examined by HPLC with electrochemical detection; L-NO2Arg did not affect noradrenaline release. The contractions induced by exogenous noradrenaline (10(-6)-10(-5) M) were enhanced by L-NO2Arg, but not by D-NO2Arg. These results suggest that the vasoconstriction induced by sympathetic nerve stimulation in the rabbit pulmonary artery is modulated by endogenous nitric oxide or nitric oxide-like substances released from endothelial cells.
Shinozuka
K
K
Department of Pharmacology, Shimane Medical University, Izumo, Japan.
Kobayashi
Y
Y
Shimoura
K
K
Hattori
K
K
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004558:Electric Stimulation; D004563:Electrochemistry; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000294:innervation / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D011651:Pulmonary Artery / Q000294:innervation / Q000502:physiology; D011799:Quinazolines / Q000494:pharmacology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology
D011799:Quinazolines; D019335:Nitroarginine; D009569:Nitric Oxide; D013779:Tetrodotoxin; D001120:Arginine; C018176:bunazosin; D009638:Norepinephrine