Negative inotropic action of corynanthine in the guinea pig papillary muscle is attenuated by glibenclamide.
1. The change in force and rate of rise of force contraction in the guinea pig papillary muscle were measured. 2. Corynanthine, an alpha-1 adrenoceptor blocking agent, produced direct negative inotropic action and inhibited the isoprenaline positive inotropic action in a dose-dependent manner (3, 10 and 30 mumol/l). 3. Addition of 1 mumol/l glibenclamide, a potent inhibitor of ATP-sensitive potassium channels, significantly antagonized the direct negative inotropic action of corynanthine, but had no effect on the antagonism between isoprenaline and corynanthine. 4. The relationships between isoprenaline and corynanthine, and corynanthine and glibenclamide are discussed.
Kocić
I
I
Department of Pharmacology, Medical Academy, Gdańsk, Poland.
D000818:Animals; D003864:Depression, Chemical; D005260:Female; D005905:Glyburide / Q000494:pharmacology*; D006168:Guinea Pigs; D007545:Isoproterenol / Q000037:antagonists & inhibitors*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects*; D015221:Potassium Channels / Q000187:drug effects; D015016:Yohimbine / Q000037:antagonists & inhibitors*
D015221:Potassium Channels; D015016:Yohimbine; D007545:Isoproterenol; D005905:Glyburide