ADRENAL-RESPONSE TO LONG-TERM HYPOXIA IS STILL INCREASED AFTER CAROTID-BODY DENERVATION IN RAT

Adrenal response to long-term hypoxia is still increased after carotid body denervation in rat. J. Appl. Physiol. 76(3): 1049-1054, 1994. - This study investigated the effects of long-term normobaric hypoxia (1 0% O-2 in N-2 for 2, 7, 14, and 28 days) on the metabolism of catechol amines in rat adrenals and the role of the carotid body chemoreceptors in the adrenal response. The content and utilization of dopamine were significantly increased from the 7th day of hypoxia and remained enha nced thereafter. The content of norepinephrine and epinephrine decreas ed after 2 days of hypoxia and increased thereafter; after 28 days of hypoxia the norepinephrine amounts remained enhanced but the epinephri ne levels were no longer significantly increased. In vivo tyrosine hyd roxylation increased after 7 days of hypoxia. Bilateral transection of the carotid sinus nerve 1 wk before hypoxia failed to abolish the inc rease in the content and utilization of dopamine after 7, 14, or 21 da ys of hypoxic exposure. These results indicate that long-term normobar ic hypoxia elicits a long-lasting increase in the metabolism of catech olamines in adrenals, especially as assessed by dopamine measurement, and that this response does not involve a carotid body chemoreflex pat hway.