Abstract
Postheparin-plasma triacylglycerol lipase (PHTGL) and postheparin-plasma monoacylglycerol lipase (PHMGH) activities in diabetic subjects with hypertriglyceridemia and non-diabetic subjects were measured. The subjects' age ranged from 61yr to 73yr in the diabetics and from 70yr to 77yr in the non-diabetics. Of 4 diabetics, one had type IIb hyperlipidemia and the others had type IV. After fasting in the morning 10U/kg of heparin was repetitively injected i. v. 3 times at 30 minutes intervals and on a separate day, 15U/kg/hour of heparin was infused i. v. by constant delivery pump for 2 hours. In some studies, postheparinplasma was preincubated with 3mg/ml of protamine sulfate and then protamine-resistant PHTGL (hepatic PHTGL) activity was measured according to the method of Krauss et al. Furthermore, protamine-inhibited PHTGL activity (mainly of adipose tissue origin) was calculated by subtracting protamine-resistant PHTGL activity from the total PHTGL activity.
Following results were obtained:
1) Effect of the repetitive i. v. injection of heparin on PHTGL and PHMGH activities; Total and protamine-inhibited PHTGL activities were significantly lower in the diabetics than in the non-diabetics. Protamine-resistant PHIGL and PHMGH activities were not significantly different between these two groups.
2) Effect of the long-term i. v. infusion of heparin on PHTGL and PHMGH activities; At 120 minutes after the infusion of heparin, protamine-inhibited PHTGL activity was significantly lower in the diabetics than in the non-diabetics, but total and protamine-resistant PHTGL and PHMGH activities were not significantly different between these two groups. These results suggest the possibility that the hypertriglyceridemia in the diabetics was caused by the decrease in PHTGL activity of extrahepatic, mainly of adipose tissue origin.
