Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 6 B358-B367, Copyright © 1995 by The Gerontological Society of America

JOURNAL ARTICLE

Age-related changes in cardiac norepinephrine release: role of calcium movement

DL Snyder, MD Johnson, V Aloyo, B Eskin and J Roberts
Department of Pharmacology, Medical College of Pennsylvania, Philadelphia, USA.

The purpose of this study was to determine if the age-related decrease in norepinephrine (NE) release from cardiac adrenergic nerve terminals is due to a defect in Ca2+ movement into the nerve terminal or to an alteration in Ca2+ activation of intracellular events leading to NE release. NE release was assessed in cardiac synaptosomes prepared from 6- and 24-month-old male F344 rats. K(+)-induced NE release was significantly greater in young vs old rats. Raising extracellular [Ca2+] increased NE release, but NE release always remained higher in the younger animals. Ionomycin, a Ca2+ ionophore, induced NE release from cardiac synaptosomes, and there was no age difference in the response. The age-related reduction in NE release induced by K+ and the capacity of ionomycin to induce similar NE release in young and old cardiac synaptosomes points to a reduction in Ca2+ movement during depolarization.

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				B. A. Eskin, D. L. Snyder, J. Roberts, and V. J. Aloyo Cardiac Norepinephrine Release: Modulation by Ovariectomy and Estrogen Experimental Biology and Medicine, February 1, 2003; 228(2): 194 - 199. [Abstract] [Full Text] [PDF]