Reflex control of circulation in the elderly.

Baroreceptor control of heart rate is markedly reduced in elderly subjects. However, the effects of aging on baroreceptor control of blood pressure and on the vascular and neurohumoral influences of volume cardiopulmonary receptors are unknown. In this paper we report evidence that in both conscious rats and humans aging is associated with a fall in the baroreceptor ability to rapidly cause blood pressure changes, but that the more long-term carotid baroreceptor control of blood pressure remains similar to that observed in younger individuals. Early and late cardiopulmonary receptor modulation of vascular resistance is impaired by aging, which also reduces the influence of this reflex on renin secretion. These dynamic and steady-state alterations in reflex cardiovascular control account for several hemodynamic abnormalities of the advanced age.