G. P. Kenny: University of Ottawa, School of Human Kinetics, 125 University Private, Room 367, Montpetit Hall, Ottawa, Ontario, Canada K1N 6N5.
Exp Physiol. 2014 Jan;99(1):196-204. doi: 10.1113/expphysiol.2013.075200. Epub 2013 Oct 18.
Adenosine has both vasodilatory and vasoconstrictive properties, yet its influence on cutaneous vascular conductance (CVC) during whole-body cooling remains unknown. The present study evaluated the influence of adenosine on reflex cutaneous vasoconstriction. Four microdialysis probes were inserted into the dorsal forearm skin of eight subjects and infused with the following solutions: (i) lactated Ringer solution (CON); (ii) 4 mm theophylline (Theo), a non-selective adenosine receptor antagonist; (iii) 10 mm l-NAME, an inhibitor of nitric oxide synthase; and (iv) combined 4 mm theophylline and 10 mm l-NAME (Theo + l-NAME). Subjects subsequently donned a water-perfusion garment. Following a thermoneutral baseline period, the suit was perfused with water at 10°C for 20 min (Cooling 1). The suit was then perfused with water at 49°C for 45 min (Heating), followed by a second cooling period of 20 min using 10°C water (Cooling 2). Cutaneous blood flow (laser-Doppler) was measured over each microdialysis probe and used to calculate CVC as a percentage of the maximum determined by sodium nitroprusside infusion and local heating. Cutaneous vascular conductance was significantly elevated at the Theo site relative to CON following Cooling 1 (18 ± 6 versus 8 ± 2%; P = 0.01) and Cooling 2 (27 ± 11 versus 14 ± 5%; P = 0.022). Likewise, CVC at the Theo + l-NAME site remained greater compared with l-NAME after Cooling 1 (13 ± 4 versus 7 ± 3%; P = 0.030) and Cooling 2 (15 ± 3 versus 9 ± 2%; P = 0.009). The present findings demonstrate that non-selective antagonism of adenosine receptors attenuates the decrease in cutaneous vascular conductance during whole-body cooling from hyperthermia.
腺苷具有血管扩张和收缩特性，但它在全身冷却过程中对皮肤血管传导（CVC）的影响尚不清楚。本研究评估了腺苷对反射性皮肤血管收缩的影响。将四个微透析探针插入八位受试者的背部前臂皮肤，并输注以下溶液：（i）乳酸林格溶液（CON）；（ii）4 毫米茶碱（Theo），一种非选择性腺苷受体拮抗剂；（iii）10 毫米 l-NAME，一种一氧化氮合酶抑制剂；和（iv）联合 4 毫米茶碱和 10 毫米 l-NAME（Theo + l-NAME）。随后，受试者穿上水灌注服。在恒温基线期后，套装以 10°C 的水温灌注 20 分钟（冷却 1）。然后，套装以 49°C 的水温灌注 45 分钟（加热），然后再用 10°C 的水进行第二次冷却 20 分钟（冷却 2）。通过激光多普勒测量每个微透析探针上的皮肤血流，并用于计算 CVC，作为通过硝普钠输注和局部加热确定的最大百分比。与 CON 相比，在冷却 1 后（18±6%对 8±2%；P=0.01）和冷却 2 后（27±11%对 14±5%；P=0.022），在 Theo 部位的皮肤血管导数值显著升高。同样，在冷却 1 后（13±4%对 7±3%；P=0.030）和冷却 2 后（15±3%对 9±2%；P=0.009），在 Theo + l-NAME 部位的 CVC 仍然大于 l-NAME。本研究结果表明，非选择性拮抗腺苷受体可减轻全身冷却从发热状态下皮肤血管传导的降低。
