Halothane attenuates the endothelial Ca2+ increase and vasorelaxation of vascular smooth muscle in the rat aorta.
Isolated spiral strips of rat thoracic aorta with endothelium were suspended for isometric tension recordings in a physiological salt solution. Endothelium-dependent vasorelaxation was elicited by carbachol 10(-6) and 10(-5) mol litre-1 during norepinephrine-induced contractions, and the effects of 1.5% and 3% halothane were evaluated with concomitant measurement of [Ca2+]i using fura-2-Ca2+ fluorescence. The effects of halothane on endothelium-dependent relaxation were compared with those of nitro G-L-arginine methyl ester 10(-4) mol litre-1 (L-NAME: an inhibitor of nitric oxide synthase). Carbachol reduced norepinephrine-induced contractions in a concentration-dependent manner, but augmented the norepinephrine-induced increase in [Ca2+]i in endothelium intact strips. In contrast, carbachol did not influence muscle tension or [Ca2+]i when the endothelium was completely denuded. Although 3% halothane and L-NAME 10(-4) mol litre-1 inhibited carbachol-induced vasorelaxation in a similar manner, halothane inhibited carbachol-induced increases in [Ca2+]i. These results indicate that halothane inhibited a carbachol-induced increase in [Ca2+]i in the endothelium, which subsequently attenuated the decrease in muscle tension.
Tsuchida
H
H
Department of Anaesthesiology, Sapporo Medical University School of Medicine, Japan.
Seki
S
S
Tanaka
S
S
Okazaki
K
K
Namiki
A
A
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D006221:Halothane / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D002217:Carbachol; D002118:Calcium; D006221:Halothane; D009638:Norepinephrine