Age-related decreases in cardiac receptor control of forearm vascular resistance in humans.

We examined 1) the relationship between the magnitudes of reflex forearm vasoconstriction during lower body negative pressure (LBNP) at -10 mmHg and ages in 59 subjects whose ages ranged from 24 to 77 years old, and 2) the slopes of the regression lines relating changes in forearm vascular resistance and those in central venous pressure in the three age-groups; those younger than 35 years old (n = 15), those between 35 and 55 years old (n = 12) and those older than 55 years old (n = 12). Forearm blood flow was measured using a strain gauge plethysmograph and forearm vascular resistance was calculated from forearm blood flow and mean blood pressure. There was a significant negative correlation (r = -0.512, p less than 0.01) between age and the magnitude of reflex forearm vasoconstriction during LBNP at -10 mmHg. The slope of the regression line in the old age-group was less (p less than 0.05) than that in the young or middle age-group. Forearm vascular responses to the cold pressor test did not differ among the three age-groups. These results suggest that cardiac receptor control of forearm vascular resistance decreases with aging in humans.