External ATP antagonizes the effect of potassium channel openers in guinea-pig ventricular papillary muscle.
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.
Bott
A
A
Department of Pharmacology, Byk Gulden Pharmaceuticals, Konstanz, Germany.
Eltze
M
M
Illes
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P
D000200:Action Potentials / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D001578:Benzopyrans / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D019806:Cromakalim; D004558:Electric Stimulation; D005905:Glyburide / Q000494:pharmacology; D006168:Guinea Pigs; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011758:Pyrroles / Q000037:antagonists & inhibitors*; D013498:Suramin / Q000494:pharmacology
D001578:Benzopyrans; D015221:Potassium Channels; D011725:Pyridines; D011758:Pyrroles; D019806:Cromakalim; C062764:Ro 31-6930; D013498:Suramin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D005905:Glyburide