Effect of puberty and estradiol on hypoxic vasomotor response in isolated sheep lungs.
We previously reported that in isolated lungs from 6-mo-old sheep acute hypoxia caused a greater vasoconstrictor response in males than in females but that this response in castrated males was not different from noncastrated males. To determine whether a gender difference exists before puberty, we compared the steady-state stimulus-response relationship of the pulmonary circulation to graded hypoxia in isolated perfused lungs of juvenile 2-mo-old male and female sheep. The flow-resistive properties of the pulmonary vessels were assessed by pressure-flow curves generated over a wide range of flows (0-150 ml X min-1 X kg-1) at six different levels of inspired O2 tension (PIO2) between 200 and 0 Torr. The stimulus-response relationship, quantified by plotting the pulmonary arterial pressure at a flow of 50 ml X min-1 X kg-1 against PIO2 was the same in juvenile male and female sheep lungs. Furthermore, the responses of juvenile sheep were not different from those of 6-mo-old males and were greater than those of 6-mo-old females. Treatment with 17 beta-estradiol (10-20 mg im) 2-5 days prior to perfusion significantly attenuated the response in the lungs from both 2-mo-old female and 6-mo-old castrated male sheep. We conclude that the gender difference in the hypoxic stimulus-response relationship observed in isolated lungs from 6-mo-old sheep arises from attenuation in the female at the time of puberty. This attenuation may be mediated by estradiol.
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002369:Castration; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008297:Male; D010100:Oxygen / Q000097:blood*; D010477:Perfusion; D011652:Pulmonary Circulation / Q000187:drug effects*; D012119:Respiration / Q000187:drug effects; D012741:Sexual Maturation / Q000187:drug effects*; D012756:Sheep; D013990:Tidal Volume; D014661:Vasoconstriction / Q000187:drug effects*
D002245:Carbon Dioxide; D004958:Estradiol; D010100:Oxygen