AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 4 621-R625, Copyright © 1984 by American Physiological Society
Relationship between type L hormone-sensitive lipase and endogenous triacylglycerol in rat heart
W. C. Miller and L. B. Oscai
The purpose of this study was to determine whether, under physiological
conditions, intracellular lipoprotein lipase [type L hormone-sensitive
lipase (HSL)] activity varied inversely with triacylglycerol (TG) content
of the heart. The results show that fasting from 7:30 A.M. to 7:30 P.M.
increased type L HSL activity from 72 +/- 1 to 96 +/- 1 U/g wet wt tissue
(P less than 0.001) in the myocardium. At the same time, cardiac TG stores
decreased from 1.83 +/- 0.03 to 1.37 +/- 0.01 mumol/g tissue (P less than
0.001). In a separate experiment, one night of eating a fat-rich diet (60%
of calories from fat) caused a 42% increase in type L HSL activity, which
was accompanied by a 42% reduction in the TG content of the heart. Likewise
cold exposure (overnight) activated type L HSL (73%) and, at the same time,
decreased cardiac TG stores (44%). When data from the fasting, fat-feeding,
and cold-exposure experiments were combined, a significant correlation
coefficient of -0.81 was obtained between type L HSL activity and TG
content of the heart (P less than 0.001). These data provide evidence for a
physiological relationship between intracellular lipoprotein lipase
activity and cardiac TG content.
