The excitatory response of the adrenal sympathetic nerve to severe hypoxia decreases in aged rats

Abstract

The age-related changes in the sensitivity of the adrenal sympathetic nerve to hypoxia were investigated in anesthetized young adult (3-4 months old) and aged rats (25-26 months old). Hypoxia with end-tidal O2 concentration FETO2) at 6-2% caused excitation of adrenal nerve activity in the young adult and the aged rats. There was a significant decrease in the responses at 3 and 2% FETO2 in the aged rats compared to the young adult rats at either peripheral chemoreceptors-intact or -denervated condition. Reduced responsiveness of the central chemoreceptors to severe hypoxia is suggested as a possible factor in the age-related decreases. © 1993.