Regulation of myocardial lipoprotein lipase activity by diabetes and thyroid hormones.
Administration of streptozotocin (100 mg/kg) to adult Sprague-Dawley rats reduced both functional (heparin releasable) lipoprotein lipase activity in perfused hearts and total and heparin-releasable lipoprotein lipase activity in isolated cardiomyocytes, and produced a hypothyroid state (decreased plasma levels of triiodothyronine and thyroxine). Administration of replacement doses of triiodothyronine (3 or 10 micrograms/kg for 3 days) to diabetic rats normalized heparin-releasable lipoprotein lipase activity in perfused hearts, but the depressed lipoprotein lipase activity in cardiomyocytes from diabetic hearts was unchanged by in vivo thyroid hormone treatment. However, hypothyroidism in thyroidectomized rats did not alter lipoprotein lipase activity in either perfused hearts or isolated cardiomyocytes. Therefore, thyroid hormones may interact with some other factor(s) in this acute, insulin-deficient model of diabetes to selectively regulate functional, heparin-releasable lipoprotein lipase activity in perfused hearts.
Liu
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Medical Research Council of Canada Signal Transduction Group, Faculty of Medicine, University of Calgary, AB, Canada.
Severson
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DL
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D006493:Heparin / Q000494:pharmacology; D007037:Hypothyroidism / Q000201:enzymology; D066298:In Vitro Techniques; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013963:Thyroid Hormones / Q000494:pharmacology / Q000502:physiology*; D013965:Thyroidectomy; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology; D014284:Triiodothyronine / Q000097:blood / Q000494:pharmacology
D001786:Blood Glucose; D013963:Thyroid Hormones; D014284:Triiodothyronine; D006493:Heparin; D008071:Lipoprotein Lipase; D013974:Thyroxine