Effects of growth hormone administration on free fatty acid and glycerol turnover in the normal dog.

Abstract

Plasma free fatty acid (FFA) and glycerol concentrations were measured in normal dogs in the post-absorptive state during a 13-day regimen of daily bovine growth hormone administration (1 mg/kg/day). Plasma FFA concentrations were transiently elevated and returned to near-control values by the seventh day of treatment. In contrast, plasma glycerol concentrations remained above control levels throughout the regimen. Glycerol turnover was measured during the regimen using constant infusions of U-14C-glycerol. The relationship between plasma glycerol concentration and turnover was found to conform to that found previously in normal untreated dogs. An equation for this relationship, and one relating plasma FFA concentration to turnover, allowed the prediction of the rates of FFA and glycerol release to plasma from observed concentration values during the growth hormone regimen. The data suggest that triglyceride lipolysis is maintained at an accelerated rate throughout the growth hormone regimen although plasma FFA concentration and turnover decline. The declining ratios of FFA:glycerol release, observed during the growth hormone regimen, suggest either an increased in situ re-esterification of fatty acids, or the in situ oxidation of some of the fatty acids which are liberated by triglyceride lipolysis. (Endocrinology85: 25, 1969)