In vivo D-chiroinositol activates skeletal muscle glycogen synthase and inactivates glycogen phosphorylase in rhesus monkeys

Abstract

Chiroinositol, a component of an inositol phosphoglycan, has been found to be reduced in the urine of humans and monkeys with non-insulin-dependent diabetes mellitus. To determine whether in vivo repletion of this inositol could improve the action of insulin on skeletal muscle glycogen synthase and glycogen phosphorylase, D-chiroinositol was administered intravenously to six monkeys during a euglycemic hyperinsulinemic clamp. Enzyme activities were determined in vastus lateralis which was freeze-clamped in situ at three time periods: immediately prior to initiation of the clamp, after steady-state glucose and insulin concentrations had been reached and the glucose disposal rate determined, and 30 min after the administration of D-chiroinositol which was superimposed on the steady-state clamp condition. D-chiroinositol increased the activity (independent and fractional velocity) of glycogen synthase ( P P