Identification of sudomotor activity in cutaneous sympathetic nerves using sweat expulsion as the effector response
ABSTRACT In a warm environment at ambient temperatures between 25 degrees and 38 degrees C (relative humidity 50%-60%) the relationship between sympathetic activity in cutaneous nerves (SSA) and pulses of sweat expulsion was investigated in five young male subjects. The SSA was recorded from the peroneal nerve using a micro-electrode. Sweat expulsion was identified on the sweat rate records obtained from skin areas on the dorsal side of the foot, for spontaneous sweating and drug-induced sweating, using capacitance hygrometry. Sweat expulsion was always preceded by bursts of SSA with latencies of 2.4-3.0 s. This temporal relationship between bursts of SSA and sweat expulsion was noted not only in various degrees of thermal sweating but also in the sweating evoked by arousal stimuli, or by painful electric stimulation. The amplitude of the sudomotor burst was linearly related to the maximal rate of increase of the corresponding sweat expulsion, the amplitude of the expulsion and the integrated amount of sweat produced for the duration of the expulsion. The results provide direct evidence that sweat expulsion reflects directly centrally-derived sudomotor activity.
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- "linear) relationship between SSNA and SCR amplitude in the study by Bini et al. (1980). Results from yet another experiment are in keeping with this: The amplitude of SSNA bursts is linearly related to the maximal rate of sweat expulsion; and, somewhat more weakly, to the integrated sweat production during the skin response (Sugenoya et al., 1990). As a further argument to their claim, Henderson et al. (2012) discuss nerve stimulation studies. "
ABSTRACT: Highlights • Sympathetic arousal can be estimated from skin conductance responses (SCR). • Such estimation relies on estimation of skin sympathetic nerve activity (SSNA). • Physiological work has established a linear relationship of SCR and SSNA amplitudes.NeuroImage 08/2013; 84(100). DOI:10.1016/j.neuroimage.2013.08.030 · 6.36 Impact Factor
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- "Sweat expulsions were identified on the sweat rate curve according to the definition as fine waves with the shape of a rapid rise followed by a rather slow decline having a frequency of less than 30 min −1 or less and a duration of 5–10 s (Ogawa et al. 1972; Sugenoya and Ogawa 1985) (see Fig. 1). We counted sweat expulsions synchronous between both forearms as reflecting centrally derived sudomotor burst activity (Fig. 1), and their average rate was calculated as an indicator of central sudomotor activity since individual sweat expulsions are regarded to reflect sympathetic sudomotor burst activity (Bini et al. 1980; Sugenoya et al. 1990). "
ABSTRACT: In summer and winter, young, sedentary male (N = 5) and female (N = 7) subjects were exposed to heat in a climate chamber in which ambient temperature (Ta) was raised continuously from 30 to 42°C at a rate of 0.1°C min(-1) at a relative humidity of 40%. Sweat rates (SR) were measured continuously on forearm, chest and forehead together with tympanic temperature (Tty), mean skin temperature (⁻Ts) and mean body temperature ⁻Tb. The rate of sweat expulsions (Fsw) was obtained as an indicator of central sudomotor activity. Tty and ⁻Tb were significantly lower during summer compared with winter in males; SR was not significantly different between summer and winter in males, but was significantly higher during summer in females; SR during winter was higher in males compared with females. The regression line relating Fsw to ⁻Tb shifted significantly from winter to summer in males and females, but the magnitude of the shift was not significantly different between the two subject groups. The regression line relating SR to Fsw was steepened significantly from winter to summer in males and females, and the change in the slope was significantly greater in females than in males. Females showed a lower slope in winter and a similar slope in summer compared to males. It was concluded that sweating function was improved during summer mediated by central sudomotor and sweat gland mechanisms in males and females, and, although the change of sweat gland function from winter to summer was greater in females as compared with males, the level of increased sweat gland function during summer was similar between the two subject groups.International Journal of Biometeorology 03/2011; 55(2):203-12. DOI:10.1007/s00484-010-0325-1 · 2.10 Impact Factor
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- "Identification and analysis of sudomotor and vasoconstrictor bursts In multi-unit recordings, SSNA is composed of sudomotor , vasoconstrictor and pilomotor nerve activities (Bini et al., 1980). Assuming that the pilomotor activities were weak or absent, we identified sudomotor and vasoconstrictor bursts as follows (Bini et al., 1980; Sugenoya et al., 1990, 1998): sudomotor bursts are those followed by skin potential responses at a latency of approximately 1.5 s and/ or by sweat expulsions at a latency of approximately 2.5 s (Fig. 1); vasoconstrictor bursts are those followed by transient vasoconstrictions at a fixed latency of approximately 3 – 5 s (Fig. 1). Theoretically, vasoconstrictions should be determined on the dorsal foot, which is supplied by the peroneal nerve. "
ABSTRACT: The effects of skin pressure applied to one side of the waist on sudomotor and vasoconstrictor nerve activity were compared with the effects on sweating and cutaneous blood flow in humans. The sweat rate and cutaneous blood flow were measured on left and right dorsal feet. Skin sympathetic nerve activity (SSNA) was recorded by microneurography from a microelectrode inserted in left and right peroneal nerves. Skin pressure was applied in a supine position to the area over the left or right anterior superior iliac spine under warm (T(a): 30-36 degrees C) and cool (T(a): 19-23 degrees C) conditions. Sudomotor and vasoconstrictor bursts were identified for quantitative analysis. The skin pressure increased the contralateral/ipsilateral ratio of the sweat rate. It also increased the contralateral/ipsilateral ratio of the cutaneous blood flow and the contralateral/ipsilateral ratio of the sudomotor burst amplitude. However, skin pressure did not induce any significant changes in the contralateral/ipsilateral ratio of the vasoconstrictor burst amplitude. The results indicate that an asymmetrical reflex effect of skin pressure on vasoconstrictor nerve activity was absent, suggesting that, whereas the ipsilateral suppression of sweating elicited by skin pressure was mediated by the sudomotor nerve system, the ipsilateral suppression of cutaneous blood flow was not mediated by the vasoconstrictor nerve system. Thus, the occurrence of the spinal reflex due to skin pressure is not uniform between the sudomotor and the vasoconstrictor nerve systems, which represent different organizations at the level of spinal cord.Autonomic Neuroscience 05/2003; 105(1):62-70. DOI:10.1016/S1566-0702(03)00021-3 · 1.37 Impact Factor