Catecholaminergic Defense against Hypothermia during Brief Cold Exposure

Abstract

The catecholamine excretion in 8 healthy subjects was investigated before and during immersion in +15 °C water for 60 min. The subjects were classified in two groups, one ‘cold-resistant’, in which the right atrial blood temperature decrease during cold exposure was less than 1.0 °C, and one ‘cold-sensitive’, in which the observed fall was 1.0 °C or more. In the ‘cold-resistant’ group cold exposure caused a marked increase in the urinary nor-adrenaline, the adrenaline excretion being statistically unaffected, while in the ‘cold-sensitive’ group the excretion of both noradrenaline and adrenaline was unchanged. It is suggested that sympathetic vasoconstriction is more important than adrenal medullary hormone secretion in the defense against hypothermia during short periods of cold exposure.

Key Words:

• Blood temperature
• catecholamine secretion
• cold exposure