AJP - Heart and Circulatory Physiology, Vol 243, Issue 5 691-H697, Copyright © 1982 by American Physiological Society
Metabolic and mechanical effects using L- and D-carnitine in working swine hearts
A. J. Liedtke, S. H. Nellis, L. F. Whitesell and C. Q. Mahar
The purpose of the present studies was to contrast the differences in
mechanical and metabolic functions between treatments of L- and D-carnitine
as measured in intact, regionally ischemic swine hearts. Coronary flows
were decreased in the anterior descending circulation (-53% delta) after an
equilibration period of 30 min during which hearts in both treatment groups
were supplemented with trace-labeled [U14-C]palmitate. Nine hearts were
selectively treated with L-carnitine (avg serum concentration 804 nmol/ml)
and were compared with eight hearts treated with D-carnitine (same dosage
schedule). No differences in fatty acid metabolism or regional shortening
were observed between treatment groups in the heart muscle rendered
moderate-to-severely ischemic. L-Carnitine did effect a significant
reduction in fatty acid uptake and labeled CO2 production as compared with
D-carnitine in aerobic tissue. This resulted in a secondary improvement in
global mechanical efficiency (expressed as a ratio of either left
ventricular developed pressure or work/global oxygen consumption) in
L-treated hearts. Higher levels of high-energy phosphate stores were also
noted in both ischemic and aerobic tissue of L-treated hearts. Thus
differences in fatty acid metabolism occurred in working swine hearts based
on the structural specificity of carnitine treatment. L-Carnitine favorably
modified oxygen consumption and global mechanical efficiency.
