The vasodilator effect of thiamylal in dog mesenteric artery: contribution of intracellular action.
The effects of thiamylal on contractions induced by various mechanisms were investigated in mesenteric arteries isolated from dogs. Thiamylal (10(-4) to 10(-3) M) significantly inhibited contractions induced by KCl (20 mM) in normal media, and those induced by norepinephrine (10(-5) M) in normal and Ca(2+)-free media. Caffeine-induced contraction was significantly inhibited by thiamylal in the concentrations greater than 3 x 10(-5) M in intact fibers and 10(-5) M in chemically skinned fibers. Chemically skinned fibers that were precontracted with Ca2+ were relaxed by thiamylal in concentrations lower than those required to relax intact fibers that were precontracted with KCl (20 mM); the ED50 was 1.52 x 10(-5) M in skinned fibers and 5.50 x 10(-4) M in intact fibers. These results suggest that intracellular mechanisms are involved in thiamylal-induced vasodilatation of dog mesenteric artery.
Nakamura
K
K
Department of Anesthesia, Kyoto University Hospital, Japan.
Hatano
Y
Y
Nishiwada
M
M
Mori
K
K
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D004285:Dogs; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D013840:Thiamylal / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D015220:Calcium Channels; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D013840:Thiamylal; D002110:Caffeine; D011189:Potassium Chloride; D009638:Norepinephrine