Effect of sulfur-containing compounds on experimental diabetes. IV. Variation in the plasma insulin level by the administration of glutathione, 2-mercaptopropionylglycine, cysteine and their oxidized type compounds

Abstract

SH and S-S compounds were administered to rabbits and variation in the plasma insulin level was assayed by the diaphragm method and by radio-immunological measurements. Plasma insulin was separated into free and bound insulins according to the method of Antoniades and others, and it was found that bound insulin can also be measured by the radio-immunological method. Loading of normal rabbit with glucose results in the increase of free insulin and lowering of bound insulin, accompanying the increase of blood sugar. Administration of adrenalin decreases both free and bound insulin. These facts indicate that variation in the plasma insulin level differs according to the rise in blood sugar from anti-insulin agent and more loading with sugar. Administration of an SH compound to normal rabbit results in the increase of free insulin about 120 minutes later, with slight fall in bound insulin. However, administration of SH compound to alloxan-diabetes rabbit resulted in a two fold increase of free insulin as assayed by the radio-immunological measurement. A corresponding decrease was seen in bound insulin. The first increase of free insulin appeared shortly after the administration (10-20 min) and this peak was not found in normal rabbits. The second increase, occurring 60-120 minutes later, was found also in normal animals. Some SH and S-S compounds are considered to play a part in the control of the Kinetic equilibrium of free and found plasma insulin.