Noradrenergic regulation of skeletal muscle oxygen pressures: Impact of heart failure with preserved ejection fraction and heat therapy.

Attenuation of sympathetic vasoconstriction during exercise (functional sympatholysis) contributes to skeletal muscle oxygen delivery-utilization matching. However, the extent to which muscle contractions impact noradrenergic regulation of interstitial oxygen pressures ( ; the driving force for blood-myocyte oxygen flux) is unknown. We tested the hypotheses that (1) muscle contractions would attenuate the noradrenaline-induced reduction in muscle compared to rest (thus indicating functional sympatholysis) in healthy rats, and (2) functional sympatholysis would be impaired in rats with heart failure with preserved ejection fraction (HFpEF) but ameliorated with heat therapy.