The effect of adrenergic agents on the activities of glycerol 3-phosphate acyltransferase and triglyceride lipase in the isolated perfused rat heart.
Glycerol 3-phosphate acyltransferase (GPAT) activity and triglyceride lipase (TGL) activity were measured in homogenates from hearts perfused with adrenergic agonists and antagonists. Perfusion with adrenalin or the beta-agonist isoprenaline produced an increase in TGL activity and a fall in GPAT activity. These changes could be imitated by incubation of heart homogenates with cAMP-dependent protein kinase. The alpha 2-agonist clondine produced the opposite effect, thus it increased GPAT activity and decreased TGL activity. Methoxamine, an alpha 1-agonist, had no effect on TGL activity but reduced GPAT activity. Continuous perfusion of the beta-antagonist atenolol reduced TGL activity to half that found in controls but also reduced GPAT activity. No change was seen on continuous perfusion of alpha 1- or alpha 2-antagonists. Changes in GPAT activity were localized mainly in the microsomal enzyme. These changes are consistent with both enzymes being regulated via a cyclic-AMP dependent protein kinase system and via alpha-adrenergic mechanisms.
D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism*; D006321:Heart / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008049:Lipase / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D010477:Perfusion; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013566:Sympathomimetics / Q000494:pharmacology*
D013566:Sympathomimetics; D001262:Atenolol; D000217:Acyltransferases; D005992:Glycerol-3-Phosphate O-Acyltransferase; D011494:Protein Kinases; D008049:Lipase; D007545:Isoproterenol; D005033:Ethylmaleimide; D004837:Epinephrine