Abstract
Cold pressor response was examined on several groups of sub jects, including 2 groups of the Ainu in Hokkaido.
1. The rise of systolic blood pressure in response to cold water immersion of a hand was more pronounced in sub jects who were born on the main island, as compared with that in those born on Hokkaido.
2. The cold pressor response of the Ainu was considerably great in comparison with that of the Japanese, although the Ainu and hybrids of Ainu-breed were self-confident of their strong resistance to cold. Accordingly, existence of ethnic difference in the response was suggested.
3. Fish factory workers as well as fishermen showed only small rise of the blood pressure in response to local cooling. The response of farmers and nurses in the coldest districts in Hokkaido was greater than that of the above fish port groups, and Japanese and Ainu-hybrid farmers in warmer districts showed also high response in the winter.
4. In the Ainu the rise of blood pressure in summer was higher than in winter. Seasonal changes in the response were negligible in hospital nurses. These findings, together with the categories 1 and 3, were interpreted possibly due to their living conditions and experiences to cold.
5. Repeated immersions of the same hand in cold water caused a diminution of blood pressure rise.
6. A highly significant correlation was demonstrated between the cold pressor response and pressor effect of norepinephrine.
7. The cold pressor response was diminished after treatment with hexamethonium bromide.
8. Cold water immersion of a hand caused a rapid transient increase in the plasma level of FFA. The increase in plasma FFA was less marked in the Ainu, as compared with the changes in the Japanese.
9. The rise of blood pressure in response to local cooling was not paralleled by the increase in plasma FFA level.
