Intra-arterial BQ-123 increased leg blood flow during exercise to a greater degree in older (+29±5 mL/min/W) compared with younger (+16±3 mL/min/W) adults, suggesting increased ET(A) activity.
Does intra-arterial administration of the ET(A) antagonist BQ-123 alter leg blood flow and oxygen consumption during exercise in healthy older versus younger adults?
ET(A) receptor blockade increases leg blood flow during exercise more in older adults than younger adults, indicating an age-related increase in ET(A)-mediated vasoconstrictor activity.
The endothelin-1 vasoconstrictor pathway contributes to age-related elevations in resting peripheral vascular tone primarily through activation of the endothelin subtype A (ET(A)) receptor. However, the regulatory influence of ET(A)-mediated vasoconstriction during exercise in the elderly is unknown. Thus, in 17 healthy volunteers (n = 8 young, 24±2 years; n = 9 old, 70±2 years), we examined leg blood flow, mean arterial pressure, leg arterial-venous oxygen (O2) difference, and leg O2 consumption (VO2) at rest and during knee-extensor exercise before and after intra-arterial administration of the ET(A) antagonist BQ-123. During exercise, BQ-123 administration increased leg blood flow to a greater degree in the old (+29±5 mL/min/W) compared with the young (+16±3 mL/min/W). The increase in leg blood flow with BQ-123 was accompanied by an increase in leg VO2 in both groups, suggesting a reduced efficiency following ET(A) receptor blockade. Together, these findings have identified an age-related increase in ET(A)-mediated vasoconstrictor activity that persists during exercise, suggesting an important role of this pathway in the regulation of exercising skeletal muscle blood flow and maintenance of arterial blood pressure in the elderly.
Barrett‐O’Keefe et al. (Mon,) conducted a other in Healthy volunteers (n=17). Intra-arterial BQ-123 (ET(A) antagonist) vs. Baseline (before administration) was evaluated on Change in leg blood flow during exercise. Intra-arterial BQ-123 increased leg blood flow during exercise to a greater degree in older (+29±5 mL/min/W) compared with younger (+16±3 mL/min/W) adults, suggesting increased ET(A) activity.