Urethane and contraction of vascular smooth muscle.
1 In vitro studies were undertaken on rat aortic strips and portal vein segments in order to determine whether or not the anaesthetic, urethane, can exert direct actions on vascular smooth muscle. 2 Urethane was found to inhibit development of spontaneous mechanical activity. This action took place with a urethane concentration as little as one tenth of that found in anaesthetic plasma concentratios, i.e., 10(-3) M. 3 Urethane (10(-3 to 10(-1) M) dose-dependently attenuated contractions induced by adrenaline, angiotensin and KCl. These inhibitory actions were observed with urethane added either before or after the induced contractions. 4 Ca2+-induced contractions of K+-depolarized aortae and portal veins were also attenuated, dose-dependently, by urethane. 5 All of these inhibitory effects were completely, and almost immediately, reversed upon washing out the anaesthetic from the organ baths. 6 A variety of pharmacological antagonists failed to mimic or affect the inhibitory effects induced by urethane. 7 These data suggest that plasma concentrations of urethane commonly associated with induction of surgical anaesthesia can induce, directly, relaxation of vascular muscle.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D004347:Drug Interactions; D004837:Epinephrine / Q000494:pharmacology; D006503:Hepatic Veins / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011169:Portal Vein / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D014520:Urethane / Q000494:pharmacology*
D000804:Angiotensin II; D014520:Urethane; D011189:Potassium Chloride; D002122:Calcium Chloride; D004837:Epinephrine