| Co-Investigator(Kenkyū-buntansha) |
NAKAI M Kyoto Pref. Univ. Med., Dept. Physiol., Instructor, 医学部, 助手 (60201662)
ITOH T Kyoto Pref. Univ. Med., Dept. Physiol., Assist. Prof., 医学部, 講師 (90168360)
NOSE H Kyoto Pref. Univ. Med., Dept. Physiol., Assist. Prof., 医学部, 講師 (40128715)
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| Research Abstract |
The aim of this project was to test a working hypothesis that blood volume has an important role in the regulations of body temperature and exercise performance. To test the hypothesis, we conducted a series of experiments on human subjects and rats, and attempts were made to elucidate the role of central venous pressure as the input signal for the changes in blood volume and the regulatory responses to maintain blood volume were analyzed.
In human experiments, we established a method to determine right atrial pressure under exercising condition, and the values were compared with blood levels of lactate, Na, catecholamine, ADH and ANP, and analyzed their roles to regulate blood volume. We also succeeded to measure blood volume of exercising
rat, and found a decrease in blood volume and an increase in plasma K concentration during exercise, proportional to exercise intensity.
Rats exposed to thermal stress showed increase in total peripheral vascular resistance proportional to the lowering of central venous pressure. When vagus nerve was cut, this response was reduced by about 40%, which indicates that the lowering of central venous pressure is prevented by lowering peripheral vascular resistance. We also found that the electrical stimulation of the central end of served vague induced the increase in vascular resistance, and the vascular compliance of hindquarter of rat is about 1/10 of total vascular compliance. All these together suggest to work to maintain central venous pressure under heat stress and during exercise.
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