Assessing effects of long-term food restriction on myocardial energetics in the isolated heart preparation

Abstract

Food restriction (FR) may increase longevity by increasing the efficiency of energy utilization by some organs. We tested whether any effect of FR on the energy efficiency of isolated, isovolumically beating hearts could be observed, by studying four groups of rats: (1) AL fed (AL) 10–13-month-old rats, (2) age matched, FR at 60% of AL rats, (3) young AL, heart weight matched to FR rats and (4) 10–13-month-old AL rats, short-term FR for the last 3 weeks of life. The oxygen cost of tension development was not different among the groups. With contractility changed by calcium, the oxygen cost of contractility was higher in the young AL than in the adult rats either AL or short-term FR. With isoproterenol, it was higher in FR than in AL groups. The basal metabolic rate of hearts was higher in the adult AL than in the short-term, but not long-term, FR rats. In the long run, FR did not significantly change the pattern of cardiac energy utilization of isolated, isovolumically beating hearts. Our observations do not lend support to the hypothesis that the anti-aging action of FR is mediated by changes in cardiac efficiency.