Reduced threshold for myocardial cell calcium intolerance in the rat heart with aging

O. Hano, K. Y. Bogdanov, M. Sakai, R. G. Danziger, H. A. Spurgeon, E. G. Lakatta

Research output: Contribution to journalArticlepeer-review

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 languageEnglish (US)
Pages (from-to)H1607-H1612
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume269
Issue number5 38-5
DOIs
StatePublished - 1995
Externally publishedYes

Keywords

  • aging heart
  • sarcoplasmic reticulum aftercontractions
  • spontaneous cytosolic calcium oscillations
  • ventricular fibrillation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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