Effect of Protein-Supplemented Fasting on Metabolic and Hormonal Responses to Epinephrine Infusion in Obese Subjects

Summary

The present study aimed at investigating the effects of an epinephrine (EPI) intravenous infusion (10 μg/min for 30 min) in normal subjects and in obese patients before and after 13 days of protein-supplemented fasting (PSF, 70 g protein/day). Blood glucose, plasma free fatty acids (FFA), lactate, insulin (IRI) and glucagon were determined before, during (15, 30 min) and after (+30 and +60 min) the EPI infusion.

1. When compared to lean control subjects, obese patients exhibited a less marked rise in blood glucose and a more important increase in plasma FFA. EPI infusion decreased IRI plasma levels in normals but not in the obese. Plasma glucagon was lower in the obese under basal conditions and their A cell reactivity to EPI was clearly reduced.

2. Comparison of the results obtained in obese patients before and after PSF revealed that EPI-induced blood glucose rise was not altered despite lower basal values after PSF. Plasma lactate response was impaired, probably because of the depletion in muscle glycogen. Reduction in basal plasma IRI was associated with a significantly higher FFA mobilization. Abnormally low basal and EPI-stimulated glucagon concentrations persisted after PSF despite concomitant reductions in blood glucose and plasma IRI.

Key-Words:

Obesity - Protein-Supplemented Fasting - Epinephrine Infusion - Blood Glucose - Lactic Acid - Free Fatty Acids - Insulin - Glucagon