Control of lipolysis in triglyceride-enriched rat hearts.
Hormonal and metabolic regulation of endogenous triglyceride hydrolysis was studied in triglyceride-enriched hearts obtained from rats fed 3 days with a trierucate-rich diet. Endogenous lipolysis was determined by measuring glycerol release during in vitro perfusion of the hearts. It appeared that there was a direct relation between the contractile state of the heart, the rate of glycerol release in the coronary effluent and the Ca2+ concentration in the perfusion medium. During Ca2+-free perfusion, 2,4-dinitrophenol stimulated oleate oxidation and this, as well as the addition of 2 x 10(-7) M glucagon, induced a marked stimulation of lipolysis. Insulin did not affect glucagon- and norepinphrine-stimulated lipolysis during substrate-free perfusion. The presented experiments point out that in lipid-enriched rat hearts the activity of the tissue lipase may be controlled by the rate of beta-oxidation and re-esterification of the liberated fatty acid, as well as by a shift to utilization of carbohydrate instead of fatty acids for energy supply.
D019297:2,4-Dinitrophenol; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004041:Dietary Fats / Q000494:pharmacology*; D004140:Dinitrophenols / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004883:Erucic Acids / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D014280:Triglycerides / Q000378:metabolism* / Q000494:pharmacology*
D004041:Dietary Fats; D004140:Dinitrophenols; D004883:Erucic Acids; D005231:Fatty Acids, Unsaturated; D007328:Insulin; D014280:Triglycerides; D005934:Glucagon; C030774:trierucate; D019297:2,4-Dinitrophenol; D002118:Calcium; D009638:Norepinephrine