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CARDIOVASCULAR EFFECTS OF NOREPINEPHRINE THERMO GENESIS IN WARM- AND COLD-ACCLIMATIZED RATS,
ARCTIC AEROMEDICAL LAB FORT WAINWRIGHT ALASKA
Pagination or Media Count:
The cardiovascular and metabolic actions of nore pinephrine NE and their interrelationships were studied at normal room temperature in anesthe tized, warm-acclimatized W-A 26 1 C and cold-acclimatized C-A 3 1 C rats. Norepine phrine caused a greater increase in the cardiac output, heart rate, stroke volume and right atri al pressure in the C-A animals than it did in the W-A animals. During the early metabolic response to NE i.e. up to 25 increase in O2 consumption there was a marked increase in the arterial pres sure of both W-A and C-A rats, with the latter showing the greater maximum response. Beyond the 25 level of increased metabolism the arterial pressure and concomitantly the systemic resistance of the C-A animals declined sharply to the prein fusion levels, where they remained throughout the course of infusion. In contrast, the arterial pressure and systemic resistance of the W-A animals remained high. It was concluded that norepinephrine calorigenesis in the C-A rat is supported by an increased cardiac reserve capacity and an ability to preferentially reduce the sys temic resistance to actively metabolizing areas. i.e. the viscera. Author
APPROVED FOR PUBLIC RELEASE