Transfer of plasma lipid to platelets by action of glucagon

Abstract

Intravenous administration of glucagon to 12 dogs and nine people produced significant depression of plasma total lipid and cholesterol at 1 2 to 2 hours. There was no significant change of whole blood total lipid. Incubation at 37°C of aliquots of blood completely or partially restored plasma lipid and cholesterol levels previously depressed by glucagon. In vitro dose-response curves showed concentrations of glucagon comparable to those following I.V. administration of glucagon (1 mg.) caused similar depression of plasma total lipid. In vitro study of the blood of seven people showed glucagon caused significant depression of plasma total lipid and cholesterol from 1 2 through 3 hours while incubation completely or partially restored depressed levels. These findings indicated glucagon lowered plasma lipid and cholesterol by transfer of lipid to the blood cell(s). Study of six people to determine the cell(s) involved showed glucagon caused significant depression of plasma lipid at 1 and 2 hours in platelet-rich plasma only while there was no change in platelet-poor blood, cell-free plasma, and normal saline controls. It was concluded the hypolipemic action of glucagon is due to transfer of plasma lipid to blood platelets which release the lipid back to plasma when the action of glucagon ceases.