Effects of Sex Hormones on Cardiovascular and Hematologic Responses to Chronic Hypoxia in Rats

Abstract

Castrated male rats exposed to high altitude (4000 m) for 5-6 wk developed right ventricular hypertrophy, increased hematocrits and increased levels of 2,3-DPG [2,3-diphosphoglycerate]. Testosterone treatment increased right ventricular wt, hematocrit and 2,3-DPG levels. The effects of high altitude and testosterone on right ventricular hypertrophy were additive. Estrogen treatment decreased hematocrit whereas progesterone had no effect. Neither female hormone affected 2,3-DPG levels or right ventricular hypertrophy. The results suggest that sex differences in the degree of right ventricular hypertrophy at high altitude and in the incidence of diseases marked by hypoxia and right heart failure may be more a function of disadvantages associated with the male hormone, testosterone, than with advantages associated with the female hormones, progesterone and estrogen.