Cardiovascular and metabolic responses to noradrenaline in man, before and after acclimatization to cold in Antarctica.

1. Four men of European descent were infused with noradrenaline at rates of 0.038, 0.075, 0.150 and 0.300 mug/kg.min in Australia, and again after 29 weeks' residence at Mawson, Antarctica. A concurrent study of their responses to whole-body cooling showed that they acclimatized to cold in Antarctica.2. Blood pressure rose and heart rate fell in proportion to the dose of noradrenaline infused. The response was much less after than before acclimatization in three of the four subjects. Subjective effects of the drug decreased in proportion to the decrease in the pressor effect.3. Finger temperature fell in proportion to the dose infused, in three subjects. The response was unchanged or increased after acclimatization.4. Oxygen consumption was initially unaffected by noradrenaline, but after acclimatization it apparently increased in proportion to the dose infused. The increase in pulmonary ventilation during infusion was slightly greater after acclimatization.