Influence of skin temperature on central thermoregulatory control of leg blood flow.

This study examined the influence of elevated skin temperature (Tsk) on the central thermoregulatory control of leg blood flow in five unanesthetized, chronically instrumented, resting baboons (Papio anubis and P. cynocephalus). In each experiment, mean iliac blood flow (MIBF), mean arterial blood pressure, arterial blood temperature (Tbl), and Tsk were measured, and iliac vascular conductance (IVC) was calculated. A heat exchanger was incorporated into a chronic arteriovenous femoral shunt to control Tbl. The protocol consisted of raising Tbl approximately 2.6 degrees C in thermoneutral environment (cool Tsk) an then again after Tsk had been elevated by environmental heating. A major influence of raising Tsk was the lowering of threshold Tbl at which the rise in MIBF and IVC commenced. This threshold Tbl was lowered at least 0.8 degrees C on the average. Also, over the whole range of Tbl studied (37.0-39.6 degrees C), MIBF and IVC were higher at high Tsk than at cool Tsk. Thus an elevation of Tsk significantly influences the control of skin blood flow by central thermoreceptors.