[Effects of ketamine on K+-contracture in isolated vascular smooth muscle from rabbit].
The effects of ketamine on contraction induced by depolarization of cell membrane (high K+-induced contracture) were studied in isolated vascular smooth muscle from rabbit portal vein. Ketamine in concentrations above 5 x 10(-4) M caused relaxation in phasic contraction, and above 10(-4) M caused relaxation in tonic contraction. These effects of ketamine at concentrations of between 10(-5) to 10(-3) M were dose dependent and reversible. In concentration above 10(-5) M, ketamine decreased the contractile response (tonic contraction) induced by 2.5 mM Ca2+ after the temporary contracture in Ca2+-free, high K+ solution. The contractile responses to norepinephrine (10(-6) M) or serotonin (10(-6) M) were also inhibited by ketamine. From these findings, it is concluded that ketamine decreases contractile responses due to transmembrane Ca2+ influx after depolarization of cell membrane and may decrease the contractile responses in concentration above 5 x 10(-4) due to Ca2+ release inhibition from sarcoplasmic reticulum.
Yamazaki
M
M
Ito
Y
Y
Momose
Y
Y
D000818:Animals; D066298:In Vitro Techniques; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology*; D011817:Rabbits
D007649:Ketamine; D011188:Potassium