THE EFFECT OF ADRENALECTOMY, DIHYDROERGOTAMINE, AND DIBENZYLINE ON THE SENSITIVITY OF RATS TO TOLBUTAMIDE.

In the rat, the magnitude of the hypoglycaemic response to a dose of tolbutamide (50 mg/kg per os) which does not depress blood glucose levels to the point where adrenal compensatory mechanisms are stimulated is unaffected by adrenalectomy. On the other hand, when a dose is given which induces a greater hypoglycaemia (100 mg/kg per os) a very significant difference between adrenalectomized and sham-operated animals is observed, the adrenalectomized rats displaying a far greater sensitivity to the hypoglycaemic action of this compound. In intact rats, the hypoglycaemia induced by tolbutamide (100 mg/kg per os) is lessened by pretreatment of the animals with Dibenzyline (4 mg/kg) but enhanced by the prior injection of dihydroergotamine (2 mg/kg). Larger doses of dihydroergotamine alone cause a reduction in glucose levels of tail blood which is greater than that found in carotid blood samples withdrawn at the same times.