Sustained enhancement of the catecholamine dynamics in rat carotid bodies, adrenals, sympathetic ganglia and target organs under long-term moderate hypoxia.

The effects of normobaric hypoxia (10% O2) for 2, 7, 14 and 28 days on the dopamine (DA), norepinephrine (NE) and epinephrine (E) dynamics (content and utilization) were investigated in carotid bodies, adrenals, heart, kidneys and three sympathetic ganglia. The results indicate that long-term hypoxia elicited a complex and sustained stimulation of the sympathoadrenal system. Four striking features were evidenced: 1) In carotid bodies, the DA, and with a delay, the NE dynamics were greatly enhanced; 2) in sympathetic ganglia, DA was the only catecholamine whose metabolism was enhanced, suggesting a chemosensitive DA pool in ganglia; 3) in nerve terminals (heart and kidneys), at variance with ganglia, the stimulation under hypoxia was evidenced by the increase in NE metabolic rate; 4) no adaptation of the sympathoadrenal activity occurred after 28 days of hypoxia, except, perhaps, for adrenals.