Effects of khellin on contractile responses and 45Ca2+ movements in rat isolated aorta.
The effects of khellin on contractile responses and 45Ca2+ flux have been studied in rat isolated aortae. Khellin (10(-5)-3.2 x 10(-4) M) produced a concentration-dependent inhibition of noradrenaline (10(-6) M) and high K+ (80 mM)-induced contractions. At 3.2 x 10(-4) M, khellin increased cAMP levels and reduced 45Ca2+ influx in resting tissues and in tissues stimulated by noradrenaline (10(-5) M) and high K+ without affecting basal 45Ca2+ efflux or noradrenaline induced 45Ca2+ efflux. It is concluded that in rat isolated aorta, khellin caused a non-specific inhibition of Ca2+ influx but may also exhibit intracellular actions, thus decreasing the availability of Ca2+ required for activation. One or more of these mechanisms may be related to an increase in intracellular cAMP levels.
Ubeda
A
A
Department of Pharmacology, Laboratory of Pharmacognosy and Pharmacodynamics, School of Pharmacy, Valencia, Spain.
Tejerina
T
T
Tamargo
J
J
Villar
A
A
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D007666:Khellin / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D007666:Khellin; D000242:Cyclic AMP; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine