The Effects of Endogenous Sex Hormones and Acute Hypoxia on Vasoconstriction in Isolated Rat Pulmonary Artery Rings

Abstract

Background: Studies have noted gender differences in various models but have not investigated whether hormone depletion will abolish these differences. Therefore, we measured isometric force displacement in normal males, castrated males, normal females, and ovarectomized females. Materials and methods: Adult male, adult female, castrated male, and ovarectomized female (250-350 g) Sprague Dawley rat pulmonary arteries (n = 7-8/group) were isolated and suspended in physiological organ baths. Force displacement was continuously recorded for 60 min of hypoxia. Data (mean +/- SEM) was analyzed with two-way analysis of variance with post-hoc Bonferroni test or Student's t-test. Results: Maximum vasodilation of normal males was -79.47 +/- 3.34%, while normal adult females exhibited a maximum vasodilation of -88.70 +/- 6.21% (P = 0.8149). In addition, delayed, phase II vasoconstriction of male pulmonary arteries rings was 89.79 +/- 7.25%, while adult females demonstrated a maximum phase II vasoconstriction of 95.90 +/- 14.23% (P = 0.9342). Hormone depletion of males exhibited a maximum vasodilation of -70.45 +/- 5.08% for castrated males as compared to -79.47 +/- 3.34% for normal adult males (P = 0.3805). Castrated males exhibited a maximum phase II vasoconstriction of 86.20 +/- 15.76% compared to 89.79 +/- 7.25% exhibited by normal adult males (P = 0.9516). Conclusions: Hormone depletion in males and females did not alter pulmonary vasoreactivity in acute hypoxia.