Effects of physiological aging on cardiac electrophysiology in perfused Fischer 344 rat hearts.

摘要: Aging effects on heart rate and atrioventricular (AV) conduction were studied in Langendorff-perfused hearts from 18 mature (4-6 mo), 12 middle-aged (12-14 senescent (24-26 mo) Fischer 344 rats. Heart decreased with increasing age 218 +/- to 196 27 (mean SD) beats/min rats 183 22 (analysis of variance, P less than 0.001). Spontaneous AV time increased 43 7 49 5 62 9 ms aging (P 0.0001). Paced also lengthened aging, Wenckebach block cycle length 122 10 133 152 16 0.005). Intra-atrial was unaffected by age. Age differences responses isoproterenol (0.5 x 10(-9) 1 10(-7) M) noted greater sensitivity at lower doses younger In separate experiments, 19 received reserpine (0.25 mg.kg-1.day-1 ip) for 6 days before study. persisted Histopathological examination nodal His-bundle tissues three each group showed intercellular collagen advancing age.(ABSTRACT TRUNCATED AT 250 WORDS)