GENDER DIFFERENCE IN AGE-RELATED-CHANGES IN MUSCLE SYMPATHETIC-NERVE ACTIVITY IN HEALTHY-SUBJECTS

Muscle sympathetic nerve activity (MSNA) was measured directly along w ith blood pressure at rest in 69 healthy women (20-79 yr old) and 76 a ge-matched healthy men (16-80 yr old). All were nonobese and normotens ive. In the women and men the MSNA was positively correlated with age (women: y = 0.78x - 5.418, r = 0.846, P < 0.0001; men: y = 0.452x + 12 .565, r = 0.751, P < 0.0001). The regression intercept of y was signif icantly lower (P < 0.0001) in the women than in the men, and the regre ssion slope was significantly steeper (P < 0.0001) in the women. The M SNA was lower in women than in men among those <30 (P = 0.0012), 30-39 (P = 0.0126), and 40-49 yr old (P = 0.0462) but was similar in women and men among those 50-59 (P = 0.1911, NS) and greater than or equal t o 60 yr old (P = 0.1739, NS). The results suggest that MSNA increases with age in women and men and that the activity is markedly lower in y oung women than in men but is markedly accelerated with age.