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Effect of heparin on serum and tissue lipases in the developing rat
Insights
Heparin administration in infant nutrition does not deplete tissue lipases. Postnatal studies show heparin releases lipoprotein lipase (LPL) and hepatic lipase (HL) proportionally to developing tissue activity.
Area of Science:
- Biochemistry
- Pediatric Nutrition
- Pharmacology
Background:
- Heparin is frequently used in infant total parenteral nutrition.
- Its effect on lipase release and tissue stores in neonates is not well understood.
Purpose of the Study:
- To investigate heparin's ability to release lipoprotein lipase (LPL) and hepatic lipase (HL) in infant rat pups.
- To assess the impact of heparin on postnatal tissue lipase stores.
Main Methods:
- Administered heparin to rat pups and adult rats.
- Measured plasma postheparin lipolytic activity (PHLA).
- Assessed lipase activities in heart, lung, and liver tissues.
Main Results:
- Plasma PHLA in rat pups increased significantly from birth to day 10.
- Heparin administration did not deplete tissue lipase activities.
- LPL activity in peripheral tissues increased postnatally, paralleling PHLA.
Conclusions:
- Heparin does not cause depletion of tissue lipases during the postnatal period.
- Heparin-induced LPL release is proportional to developing tissue lipolytic activity in infants.
Abstract:
The frequent inclusion of heparin in fluids used for total parenteral nutrition in infants, prompted an investigation of the ability of heparin to release lipoprotein lipase (LPL) and hepatic lipase (HL) from the endothelial surface into the circulation, and of the effect of heparin on tissue stores of lipase in the postnatal period. In rat pups, plasma postheparin lipolytic activity (PHLA) released by IP administration of heparin (0.5 unit/g body wt) was 15% of adult values at birth and increased rapidly to reach 60% on day 10. Repeated doses of heparin (in adult rats, given 0.1 unit/g IV) at 1 and 4 h after the initial dose did not affect the maximal response to heparin. In all age groups 80% of PHLA was inhibited by 0.5 M NaCl, suggesting a mostly nonhepatic origin for the released enzyme. Heart, lung, and liver lipase activities of rat pups were not significantly different from controls not given heparin. The pattern of change in tissue enzyme content was similar for heart and lung, but different from hepatic lipase. LPL activity in the former increased from 10 and 30% to 60 and 100% of adult values between birth and 10 days while in the latter enzyme activity exceeded adult levels at birth and decreased to 50% of adult values during the latter half of the suckling period (days 10-21). Our results demonstrate that heparin does not cause depletion of tissue lipases in the postnatal period. The parallel increases in LPL content of peripheral tissues and PHLA suggest that in all age groups heparin-induced release of LPL into the circulation is proportional to tissue lipolytic activity.