Co-ordination of hepatic and adipose tissue lipid metabolism after oral glucose

The integration of lipid metabolism in the splanchnic bed and in subcutaneo us adipose tissue before and after ingestion of a 75 g glucose load was stu died by Fick's principle in seven healthy subjects. Six additional subjects were studied during a hyperinsulinemic euglycemic clamp. Release of non-es terified fatty acids (NEFA) from adipose tissue and splanchnic NEFA extract ion followed a similar timecourse after oral glucose, and there was a highl y significant relationship between adipose tissue NEFA release and splanchn ic NEFA uptake. There was no immediate inhibition of splanchnic very low de nsity lipoprotein (VLDL)-triacylglycerol (TAC) output when plasma insulin l evels increased after glucose, Adipose tissue extraction of VLDL-TAG tended to vary in time in a manner similar to splanchnic VLDL-TAG output and the two were significantly related. The area-under-curves (AUC) for splanchnic extraction of NEFA was significantly lower than that for output of VLDL, im plying depletion of hepatic TAG stores during the experiment. In the hyperi nsulinemic clamp experiments, there was on average suppression of splanchni c VLDL-TAG output although between-person variability was marked, This supp ression could be explained by a very low supply of NEFA during the clamp.jl r We conclude that there is an integrated pattern of metabolism in splanchn ic and adipose tissues in the postabsorptive and post-glucose states, Flux of NEFA from adipose tissue drives splanchnic NEFA uptake, Splanchnic VLDL- TAG secretion appears to be regulated by a number of factors and in turn co ntrols TAG extraction in adipose tissue. Insulin does not seem to play a ke y role in the acute regulation of hepatic VLDL metabolism under these parti cular conditions in vivo.