Pacing-induced transient depolarizations in rabbit atrial myocardium.
Transient afterdepolarizations (TD) were analyzed following a train of paced action potentials in isolated pectinate muscles bordering the crista terminalis in rabbit right atria. After cessation of a rapid drive TD peaked between 400 and 700 ms. The amplitude of TD were found to be pacing-dependent (maximum at 250 ms pre-drive pacing interval 12.9 +/- 2.2 mV, n = 27). At pacing intervals longer than 1000 ms no TD could be observed but pacing intervals shorter than 250 ms provoked a triggered activity. Verapamil (13.2 X 10(-6) mol.1(-1) completely blocked pacing-induced TD. TD could be described quantitatively using a model of the transient inward current.
D000818:Animals; D016275:Atrial Function; D006339:Heart Rate; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D011817:Rabbits; D014700:Verapamil / Q000494:pharmacology
D014700:Verapamil