Evidence for alpha 2-adrenoceptor agonist activity of minoxidil.
The present investigation was undertaken to study the mechanism of action of minoxidil using various smooth muscle preparations. Minoxidil (4.7 x 10(-6) M to 4.7 x 10(-4) M) produced a concentration-dependent inhibition of field stimulation-evoked responses in rat anococcygeus muscle and vas deferens. The inhibition produced by minoxidil was antagonized by yohimbine (2.5 x 10(-7) M). Minoxidil (1.4 x 10(-5) M to 4.7 x 10(-4) M) also produced a concentration-dependent relaxation in oestrogen-primed potassium chloride-depolarized rat uterus. These responses were blocked not only by yohimbine but also by glibenclamide (2.02 x 10(-8) M). Our results suggest that minoxidil possesses alpha 2-adrenoceptor agonist activity in addition to potassium-channel-opening activity.
Sharma
N
N
Department of Pharmacology, L. M. College of Pharmacy, Ahmedabad, India.
Mehta
A A
AA
Santani
D D
DD
Goyal
R K
RK
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D004054:Diethylstilbestrol / Q000494:pharmacology; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008914:Minoxidil / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects*; D014590:Uterine Contraction / Q000187:drug effects; D014649:Vas Deferens / Q000187:drug effects; D015016:Yohimbine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D015221:Potassium Channels; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D008914:Minoxidil; D004054:Diethylstilbestrol; D005905:Glyburide