Whole?￠????body heat stress and exercise stimulate the appearance of platelet microvesicles in plasma with limited influence of vascular shear stress

摘要

Intense, large muscle mass exercise increases circulating microvesicles, but our understanding of microvesicle dynamics and mechanisms inducing their release remains limited. However, increased vascular shear stress is generally thought to be involved. Here, we manipulated exercise?￠????independent and exercise?￠????dependent shear stress using systemic heat stress with localized single?￠????leg cooling (low shear) followed by single?￠????leg knee extensor exercise with the cooled or heated leg (Study 1, n ????=????8) and whole?￠????body passive heat stress followed by cycling (Study 2, n ????=????8). We quantified femoral artery shear rates (SRs) and arterial and venous platelet microvesicles (PMV?￠????CD41 + ) and endothelial microvesicles (EMV?￠????CD62E + ). In Study 1, mild passive heat stress while one leg remained cooled did not affect [microvesicle] ( P ?????￠???￥????0.05). Single?￠????leg knee extensor exercise increased active leg SRs by ~12?￠????fold and increased arterial and venous [PMVs] by two?￠???? to threefold, even in the nonexercising contralateral leg ( P ????