PITUITARY AND ADRENALS ARE REQUIRED FOR HYPERGLYCEMIC REFLEX INITIATED BY STIMULATION OF CBR WITH CYANIDE

We have previously shown that stimulation of carotid body receptors (C BR) with sodium cyanide (NaCN) elicits a rapid hyperglycemic reflex. H ere we explore whether the pituitary and adrenals, two glands involved in glucose homeostasis, are necessary for this reflex. Experiments we re performed on anesthetized rats that were artificially ventilated. M easurements of hepatic venous-arterial glucose difference indicated th at CBR stimulation with a bolus of 5 mu g/100 g NaCN produced an immed iate increase in the output of glucose by the liver. The same dose of NaCN failed to increase hepatic output of glucose in rats with bilater al adrenalectomy or in rats 1 wk after surgical removal of neurohypoph ysis. Reflex glucose output by the liver was maintained after adenohyp ophysectomy or in adrenalectomized rats after adrenal autotransplantat ion to epiploon. Measurements of epinephrine in plasma and in the graf ted adrenal tissue showed that the adrenal autograft can store and sec rete catecholamines. Immunocytochemical observations indicated that th e grafted adrenals retain medullary cells. These results indicate that neurohypophysis and adrenals are necessary for the hyperglycemic refl ex initiated by CBR stimulation with NaCN and that the participation o f these two organs in this reflex is probably humoral.