Influence of ageing on the sympathetic nervous system and adrenal medulla at rest and during stress.

The influence of ageing on the sympathetic nervous system and adrenal medulla was studied neurochemically in humans, using isotopic dilution measurement of regional and whole body catecholamine release to plasma in humans. With ageing, sympathetic activation was evident in the heart, and the gut and liver at rest. The mechanism appeared to be by activation of sympathoexcitatory noradrenergic suprabulbar projections from the brainstem. Sympathetic nervous responses with stressors were augmented. Conversely, adrenal medullary release of epinephrine was subnormal in the elderly, at rest and during stress.