The effects of aging on the electrophysiologic and hemodynamic responses to nifedipine in isolated perfused hearts.
Age effects on responses to calcium channel blockade with nifedipine were studied in isolated Langendorff-perfused Fischer 344 rat hearts. Responses to 25 min of perfusion with nifedipine concentrations of 0, 25, 50, 75, and 100 ng/ml were studied in hearts from 11 mature (6 months) and 13 senescent (23-27 months) male F344 rats. Nifedipine produced significant increases in the atrial cycle length (p less than 0.001), paced atrioventricular (AV) conduction time (p less than 0.001), AV Wenckebach cycle length (p less than 0.001), left ventricular (LV) diastolic pressure (p less than 0.001), and decreases in LV systolic pressure (p less than 0.001) and peak dP/dt (p less than 0.001) in hearts from both mature and senescent rats. Greater decreases in the atrial rate (p less than 0.05) and depression of peak dP/dt (p less than 0.05) were detected in senescent vs. mature rat hearts. No age difference in responses of AV conduction parameters were detected although increases in the AV Wenckebach cycle length appeared to be greater in senescent hearts at concentrations greater than 75 ng/ml.
Schmidlin
O
O
Department of Medicine, University of California, San Francisco 94143-0124.
Garcia
J
J
Schwartz
J B
JB
D000375:Aging / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D015425:Myocardial Reperfusion; D009543:Nifedipine / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D016277:Ventricular Function, Left / Q000187:drug effects
D009543:Nifedipine