The effects of aminophylline on adenosine and ATP actions on sinoatrial conduction in the isolated, blood-perfused dog atrium.
The effects of adenosine and adenosine triphosphate (ATP) on sinus cycle length (SCL) and sinoatrial conduction time (SACT) estimated by constant atrial pacing were studied in isolated, blood-perfused canine right atria. Adenosine and ATP were infused into the sinus node artery at a rate of 1, 2 and 4 micrograms/min. Both adenosine and ATP caused an increase in SCL and SACT in a dose-dependent manner and decreased atrial developed tension. There was no significant difference between the effect of adenosine and that of ATP on SCL and SACT. The prolongation of SACT induced by 4 micrograms/min of adenosine and ATP was significantly inhibited by a single injection of 1 to 3 mg of aminophylline, although this dose level of aminophylline did not significantly suppress the prolongation of SCL produced by adenosine and ATP. From these results it is concluded that both adenosine and ATP lengthen SCL and SACT in a dose-related manner, and that aminophylline blocks the increase in SACT much more easily than that in SCL.
D000241:Adenosine / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D010477:Perfusion; D012849:Sinoatrial Node / Q000187:drug effects*; D013997:Time Factors
D000628:Aminophylline; D000255:Adenosine Triphosphate; D000241:Adenosine