The roles of the Na + /K + ?￠????ATPase, NKCC, and K + channels in regulating local sweating and cutaneous blood flow during exercise in humans in????vivo

摘要

Na + /K + ?￠????ATPase has been shown to regulate the sweating and cutaneous vascular responses during exercise; however, similar studies have not been conducted to assess the roles of the Na?￠????K?￠????2Cl co?￠????transporter (NKCC) and K + channels. Additionally, it remains to be determined if these mechanisms underpinning the heat loss responses differ with exercise intensity. Eleven young (24???????±????4????years) males performed three 30?￠????min semirecumbent cycling bouts at low (30% VO 2peak ), moderate (50% VO 2peak ), and high (70% VO 2peak ) intensity, respectively, each separated by 20?￠????min recovery periods. Using intradermal microdialysis, four forearm skin sites were continuously perfused with either: (1) lactated Ringer solution (Control); (2) 6????mmol???·L ?￠????1 ouabain (Na + /K + ?￠????ATPase inhibitor); (3) 10????mmol???·L ?￠????1 bumetanide (NKCC inhibitor); or (4) 50????mmol???·L ?￠????1 BaCl 2 (nonspecific K + channel inhibitor); sites at which we assessed local sweat rate (LSR) and cutaneous vascular conductance (CVC). Inhibition of Na + /K + ?￠????ATPase attenuated LSR compared to Control during the moderate and high?￠????intensity exercise bouts (both P ????????????0.01), whereas attenuations with NKCC and K + channel inhibition were only apparent during the high?￠????intensity exercise bout (both P ?????￠???¤????0.05). Na + /K + ?￠????ATPase inhibition augmented CVC during all exercise intensities (all P ????????????0.01), whereas CVC was greater with NKCC inhibition during the low?￠????intensity exercise only ( P ????????????0.01) and attenuated with K + channel inhibition during the moderate and high?￠????intensity exercise conditions (both P ????????????0.01). We show that Na + /K + ?￠????ATPase, NKCC and K + ????channels all contribute to the regulation of sweating and cutaneous blood flow but their influence is dependent on the intensity of dynamic exercise.