Insulin effect upon the "in vitro" glucose uptake by the white rat thymus during the age - and hydrocortisone - induced thymus involution.

Insulin at a physiological concentration (10(-3) IU/ml incubation medium) did not modify the glucose uptake by the thymuses of young rats, but increased significantly the glucose uptake by the involuted thymuses of older animals. Insulin at the same concentration enhanced the glucose uptake of the thymuses which underwent an accidental hydrocortisone-induced involution. Parallely, the effect of insulin on insulin dependent peripheral tissues (diaphragm and epididymal fat pad) was followed. In the presence of cystine (4.13 mumole/ml) in the incubation medium increased the glucose consumption by the thymus of young rats. This fact is discussed on the basis of the -S-S bond-protecting effect of cystine against the distroying effect of free -SH groups released from the thymus into the incubation medium.