Endothelial binding sites for lipoprotein lipase are not diminished in perfused hearts from diabetic rats.
The possibility that diabetes reduces functional, heparin-releasable lipoprotein lipase (HR-LPL) activity on the coronary vasculature of perfused hearts by altering endothelial binding sites for the enzyme was examined by measuring the binding and subsequent heparin-induced release of exogenous lipoprotein lipase purified from bovine milk (mLPL). Rat hearts were first perfused with heparin (5 U/mL) for 5 min to displace endogenous HR-LPL into the perfusate. The subsequent perfusion of control hearts with 0.05-2 micrograms/mL mLPL resulted in a progressive increase in bound exogenous enzyme that could be released by a second heparin perfusion. Induction of an acute, insulin-deficient model of diabetes (100 mg/kg streptozotocin 4-5 days prior to heart perfusions) reduced endogenous HR-LPL activity, but the binding and heparin-induced release of mLPL (0.5 microgram/mL) were the same as measured in control hearts. Therefore, diabetes does not alter low-affinity, high-capacity proteoglycan binding sites for mLPL on the endothelium of perfused hearts.
Liu
L
L
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Calgary, Canada.
Severson
D L
DL
D000818:Animals; D001665:Binding Sites; D003331:Coronary Vessels / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000502:physiology; D066298:In Vitro Techniques; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley
D008071:Lipoprotein Lipase