ro-31-6930 and alpha-beta-methyleneadenosine-5--triphosphate

Right ventricular papillary muscles of the guinea-pig heart were electrically stimulated. Cromakalim 10-100 microM and Ro 31-6930 3 microM depressed the contractile force and shortened the duration of action potentials. Glibenclamide 0.3-3 microM, ATP 100 microM and alpha, beta-methylene ATP (alpha, beta-meATP) 30 microM antagonized these effects. Suramin 300 microM failed to reverse the alpha, beta-meATP-evoked antagonism of the action of cromakalim. It is concluded that both intra- and extracellular ATP may interfere with potassium channel openers and that extracellular ATP does not act via the known P2-purinoceptor subtypes.

Topics: Action Potentials; Adenosine Triphosphate; Animals; Benzopyrans; Cromakalim; Electric Stimulation; Glyburide; Guinea Pigs; Male; Myocardial Contraction; Papillary Muscles; Potassium Channels; Pyridines; Pyrroles; Suramin