Abstract
To determine whether advancing age is accompanied by a reduced Ca2+ tolerance, we measured Ca2+-dependent diastolic pressure, prolonged relaxation and systolic functional deterioration, spontaneous sarcoplasmic reticulum (SR)-generated Ca2+ oscillations (detected as scattered laser light intensity fluctuations (SLIF)], aftercontractions, and ventricular fibrillation in isolated, isovolumic, atrioventricular-blocked intact hearts from 24- to 26-mo (old) and 6- to 8-mo (young) male Wistar rats. In enzymatically isolated single cardiac myocytes, the likelihood of the occurrence of spontaneous contractile waves driven by spontaneous SR Ca2+ release was also determined. In response to stepwise increases in perfusate Ca2+ concentration (Ca(o)), a reduction in the maximum developed pressure accompanied by an elevation in end-diastolic pressure and a prolonged contraction duration was observed at lower Ca(o) in old vs. young hearts (P < 0.01 for each parameter). Furthermore, Ca2+-dependent ventricular fibrillation occurred during pacing in six old but in no young hearts (P < 0.01), aftercontractions were observed in seven old vs. one young heart (P < 0.01), and SLIF increased to a greater extent in old vs. young hearts. In single cardiac myocytes, spontaneous contractile waves occurred more frequently with increasing age (P < 0.01). These results indicate that aging is associated with an increased likelihood for the occurrence of SR- generated Ca2+ oscillations and functional abnormalities that result from these oscillations.
Original language | English (US) |
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Pages (from-to) | H1607-H1612 |
Journal | American Journal of Physiology - Heart and Circulatory Physiology |
Volume | 269 |
Issue number | 5 38-5 |
DOIs | |
State | Published - 1995 |
Externally published | Yes |
Keywords
- aging heart
- sarcoplasmic reticulum aftercontractions
- spontaneous cytosolic calcium oscillations
- ventricular fibrillation
ASJC Scopus subject areas
- Physiology
- Cardiology and Cardiovascular Medicine
- Physiology (medical)