[Aging and efficiency of the baroreflex arc. Analysis of a large sample of normal individuals studied with a computerized technic].

Previous studies, with manifold contradictions, have shown the baroreflex progressive damage in the elderly. A group of 178 normal subjects, between 11 and 88 years age, were investigated by measuring their blood pressures and R-R intervals while at rest and during the Valsalva manoeuvre, deep breathing at 6 breaths/min, and standing up from a lying position. The parasympathetic parameters decreased with ageing; mean heart rate and its response during standing up diminished, suggesting a cardiac ortho-sympathetic alteration; and basal blood pressures increased, while its responses at the last manoeuvre did not change. All this indicates that cardiac parasympathetic activity is reduced and vascular ortho-sympathetic activity--C1 group--is increased. Probably, the cardiac ortho-sympathetic findings are originated by the receptors--because of the C1 neuronal hyperactivity. The destruction of inhibitory afferents with ageing could explain this hyperactivity.