Effects of slow and rapid cooling on catecholamine concentration in arterial plasma and the skin

Abstract

Norepinephrine (NE) and epinephrine (Epi) concentrations in arterial plasma and in skin tissue were measured chromatographically before and after external cooling. Urethan-anesthetized rats were cooled either slowly (0.004–0.006°C/s) or rapidly (0.03– 0.05°C/s). Blood samples were drawn three times from each animal: 1) before cooling and at a rectal temperature decreased 2) by 0.5°C and 3) by 3–4°C. Skin samples were taken from controls and from rapidly or slowly cooled rats at a rectal temperature lowered by 0.5°C. The resting mean values were 36.7 ± 0.3°C for rectal temperature, 0.62 ± 0.079 and 1.09 ± 0.203 ng/ml for plasma NE and Epi, and 85.6 ± 4.1 and 137.6 ± 34.3 ng/g for skin NE and Epi. A decrease in rectal temperature by 0.5°C at rapid cooling produced a 2.6-fold increase of NE and a 2.8-fold increase of Epi in plasma. Concomitantly, there was a significant decrease in skin NE concentration by 28% and Epi by 86%. At a rectal temperature decreased by 0.5°C after slow cooling, plasma catecholamines did not change; at unaltered skin NE concentration, there was a reduction in skin Epi concentration (60%). When rectal temperature was lowered by 3–4°C, the increase in plasma NE was virtually the same at both cooling rates and only plasma Epi increased more after deep rapid cooling than slow cooling. Thus the sympathoadrenal system may be differently activated depending on cooling rate. Rapid cooling, when the dynamic activity of the skin cold receptors is involved in the cold response, may provide conditions for an earlier activation of the sympathoadrenal system. This may evidence the functional significance of the dynamic activity of the skin cold receptors in the formation of the cold defense responses.

The existence of a linear system consisting of sympathetic endings in rat skin

“…The measurements of Kozyreva et al (1999) showed that both adrenaline and noradrenaline exist in rat skin. Also, earlier research identified chromaffine cells in the cat skin (Burch and Phillips 1958).…”

Effect of substance P on thermoregulation parameters during different cooling modes

“…after nonepinephrine treatment and vasoconstriction, although at low vascular tone) [9]. Probably, potentiation of vasoconstriction during SC in rats receiving SP and the absence of the modulatory effect of this peptide on vascular reactions induced by RC can be explained by differences in the degree of sympathetic activation during various cooling rates [5].…”

“…Our previous studies showed that dynamic activity of peripheral thermoreceptors plays an important role in the regulation of functional systems, maintaining temperature homeostasis and in modulation of the hormonal status of the organism during cooling. It can be hypothesized that different degree of participation of sympathetic system during various modes of cooling [3][4][5] can be one of the reasons underlying different effects of SP observed during RC and SC.…”

The effect of icepack cooling on skin and muscle temperature at rest and after exercise

“…17 On the one hand, rapid skin cooling evokes a significant increase in plasma catecholamines with a reduction in skin catecholamines. The fall in skin catecholamines is attributed to their local release to cause vasoconstriction.…”