Age-associated changes in cardiovagal baroreflex sensitivity are related to central arterial compliance

Cardiovagal baroreflex sensitivity (BRS) declines with advancing age in hum ans, but the underlying mechanism has not been established. Using two diffe rent approaches, we determined the relation between age-associated decline in cardiovagal BRS and the compliance of an artery in which arterial barore ceptors are located. First, we measured carotid artery compliance (via the simultaneous application of ultrasonography and arterial applanation tonome try) and cardiovagal BRS (phase IV of the Valsalva maneuver) in 47 healthy sedentary men that varied widely in age (19-76 yr). Cardiovagal BRS decline d progressively with age (r = -0.69; P less than or equal to 0.001) and was positively related to carotid artery compliance (r = 0.71; P less than or equal to 0.001). Stepwise multiple-regression analysis revealed that caroti d artery compliance was the strongest independent physiological correlate o f cardiovagal BRS and that it explained 51% of the total variance. Second, we studied 13 middle-aged and older previously sedentary men (age 56 +/- 2 yr) before and after 13 wk of aerobic exercise intervention. Regular exerci se increased both cardiovagal BRS and carotid artery compliance (P<0.05) an d the two events were strongly and positively related (r = 0.72; P<0.01). W e conclude that reduced carotid artery compliance may play an important mec hanistic role in age-associated decrease in cardiovagal BRS in healthy sede ntary humans.