Adenosine receptor inhibition attenuates cutaneous vasoconstriction during whole‐body cooling

It has been suggested that adenosine may modulate cutaneous vasoconstriction. Therefore, we examined if adenosine receptor inhibition would attenuate decreases in cutaneous vascular conductance (CVC) during cold stress. Two microdialysis probes were inserted into the dermis layer of the forearm in eight subjects (4 females, 4 males). The probes were infused continuously with Ringer's lactate (CON) or theophylline (THEO). Skin blood flow was measured continuously (laser‐Doppler) to calculate CVC (% of max). Following 45 min of infusion to ensure complete blockade of adenosine receptors, subjects were exposed to two 20 min periods of whole‐body cooling (via water‐perfused suit), each separated by 45 min of heat stress. Decreases in CVC did not differ between CON and THEO sites during the first cooling period (p=0.218). CVC increased to similar levels during the heat stress period (p=0.820). During the second cooling period, CVC was modeled using nonlinear regression, which revealed that the curves differed between sites (F (4,168) = 7.712, p<0.01). Minimum values of CVC were significantly greater at THEO (38 ± 10%) compared to CON (19 ± 13%, p<0.01). These results suggest that adenosine receptor inhibition significantly attenuates cutaneous vasoconstriction during whole‐body cold stress, but only following cutaneous vasodilation induced via passive heating. Supported by NSERC grant RGPIN‐298159–2009 (held by GP Kenny).