Individual vasodilatory response heterogeneity during progressive forearm exercise: evidence for vasodilator phenotypes

PURPOSETo determine whether vasodilator and/or pressor response phenotypes are present during a perfusion pressure induced perturbation to exercising muscle oxygen delivery (O2D).METHODS10 healthy male subjects (19.5±0.4 yrs) completed two trials of progressive handgrip exercise to exhaustion (2.5kg increments every 3.5 mins) in each forearm above and below heart level (forearm arterial perfusion pressure (FAPP) Δ 29.5±0.97mmHg). Forearm blood flow ((FBF (ml/min); brachial artery Doppler and echo ultrasound), mean arterial blood pressure (MAP (mmHg); finger photoplethysmography) and O2D (ml/O2/min; venous effluents) were measured at the end of each work rate (WR).RESULTSGroup level, Δ FBF was compromised beyond the 5kg WR in above vs. below. There was no vasodilatory (P=0.21) or exercise pressor (P=0.63) response, and submax O2D, submax and peak VO2 and peak WR were compromised by reduced FAPP (all P<0.05). In contrast, individual responses revealed compensatory vasodilators (n=6) and those who did not (n=4). Vasodilators blunted the FAPP‐evoked reduction in submax O2D and VO2 compared to non‐vasodilators (P<0.05), and experienced less of a compromise to peak WR (P<0.05).CONCLUSIONSIn the current model, vasodilatory response phenotypes exist, which determine hypoperfusion susceptibility and the degree to which aerobic metabolism and exercise performance are compromised. NSERC.

Individual vasodilatory response heterogeneity during progressive forearm exercise: evidence for vasodilator phenotypes Journal Articles