Chronotropic responses to large doses of adenosine and ATP in dog isolated atria.

Double-peaked positive chronotropic responses of isolated and cross-perfused dog atria to ATP.

“…Burnstock and Meghji (10) showed in 1981 that ATP and adenosine induced only a negative chrono tropic effect, but ADP and AMP had an initial positive effect followed by a negative chronotropic effect in frog hearts. More recently, Chiba et al (11) briefly reported that ATP frequently induced double peaked positive chronotropic effects at large doses in the isolated dog atrial preparation which was developed by Chiba et al (12,13). In the present study, we used adrenergic beta blocking agents, propranolol and carteolol, aminophylline and quinidine on ATP-induced effects in order to investigate whether ATP induced positive chronotropic effects involve stimulation of beta-adrenoceptors, P1 purinoceptors or P2-purinoceptors in the dog atrium.…”