Vasodilator component in sympathetic nerve activity destined for the skin of the dorsal foot of mildly heated humans

Skin sympathetic nerve activity (SSNA) was recorded in seven male subjects from the peroneal nerve by microneurography, and the temporal correspondence of spontaneously occurring SSNA bursts with vasodilatation and sweating responses on the dorsal foot was studied during a mild body heating at rest.Some SSNA bursts were followed by a sweat expulsion with a latency of 2.4 ± 0.4 s, and some bursts by a transient vasodilatation with a latency of 2.2 ± 0.4 s (means ± s.d.). SSNA bursts followed both by a sweat expulsion and by a vasodilatation response (Type 1), those followed only by a sweat expulsion (Type 2) and those followed only by a vasodilatation response (Type 3) were 70 %, 10 % and 1 % of the total bursts examined, respectively.For Type 1 bursts, there was a significant, but weak linear relationship among the burst amplitude, the amplitude of the corresponding vasodilatation and the amplitude of the corresponding sweat expulsion.It was concluded that SSNA contains vasodilatory activity which is synchronous with sudomotor nerve activity. The results suggest that such vasodilatory activity contributes to sustaining the sweat gland function by supplying sufficient blood

COULD THE OCULAR SURFACE TEMPERATURE BE AN INDICATION OF CORE TEMPERATURE?

The present study was carried out to examine the hypothesis that ocular surface temperature measured at the site over the iris by an infrared radiation thermometer could be an indication of core body temperature. In healthy young subjects, ocular surface (T_<os>), tympanic(T_<ty>), esophageal(T_<es>), mean skin(T^-_<sk>) temperatures, and local sweating rates and skin temperature of the forehead(T_<sf>) were measured in a chamber controlled at a moderate climate of 28℃-40%(rh) on two separate tests, a passive body warming and an exercise. The passive body warming was induced by immersion of lower limbs in hot water bath regulated 43℃. The moderate exercise was performed with cycle ergometer at the intensity of 80 W. In both tests, T_<os> didn't follow either core (T_<ty>, T_<es>) or shell (T^-_<sk>, T_<sf>) body temperatures. In the second series of experiments, ambient temperature (T_<am>) was raised from 27℃ to 34℃, or lowered from 34℃ to 27℃ for 10 min. In both tests, T_<os> followed the change of (T_<am>) rapidly in spite of the steady T_<ty>, and the change rates of T_<os> were greater than of T_<sf>. When T_< am> was raised slowly from 20℃ to 23℃ for 20 min, the T_<os> rise was almost simultaneous with the T_<am> rise, and there was a high correlation between these two factors (r=0.99). Moreover, the regional thermograms around eyes showed that skin temperature surrounding eyes was significantly higher than T_<os> (p<0.01). These results suggest that ocular surface temperature measured by an infrared radiation thermometer might reflect corneal temperature rather than iris temperature, and could not be an indication of core temperature