[The influence of endogenous insulin and glucagon on the free fatty acids in the circulating blood plasma].

The effect of increased endogenous plasma insulin and glucagon concentrations on the free fatty acid (FFA) levels in the circulating blood was investigated in sheep, 2 baboons and 1 vervet monkey. Elevation of the plasma insulin level was obtained by vagal stimulation or intravenous glucose administration and vagal stimulation, whereas increased glucagon levels were induced by sympathetic stimulation, increased plasma insulin levels, with simultaneous increased plasma glucose concentrations (in our experiments with sheep), produced a pronounced lowering of the FFA levels. From this observation a lipogenetic function could be ascribed to insulin. However, in the primate experiments, increased plasma insulin without concomitant glucose administration caused an elevation of FFA levels, and would indicate a lipolytic rather than a lipogenetic action of insulin. Increased glucagon levels, as produced by sympathetic stimulation, did not alter the FFA concentrations significantly. It thus appears that glucagon has no lipolytic effect, as claimed by previous investigators. In our experiment on the vervet monkey, sympathetic stimulation, with increased plasma glucagon, even caused a decrease in FFA levels.