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Sex differences in osmotic regulation of AVP and renal sodium handling

Report Among the Highlighted Topics on Gender Differences in the October Edition of the Journal of Applied Physiology

BETHESDA, Md. -- October 18, 2001 -- The American Physiological Society (APS) kicks off a special series entitled, “Highlighted Topics on Gender Differences in Physiology,” beginning with the October 2001 edition of the Journal of Applied Physiology, the Society’s flagship publication. The October issue offers the following examination:

"Sex Differences in Osmotic Regulation of AVP and Renal Sodium Handling," is the highlighted mini-review of Nina S. Stachenfeld, Andres E. Splenser, Wendy L. Calzone, Matthew P. Taylor, and David L. Keefe from The John B. Pierce Laboratory and Departments of Epidemiology and Public Health, Yale University School of Medicine, and Women and Infants Hospital, Brown University School of Medicine. The authors address sex hormone effects on the regulation of body fluids and blood pressure.

In addition to the role of sex hormones in reproduction, they also have an important effect on other physiological systems, which may explain differences in disease progression between men and women. The mechanisms underlying gender differences in blood pressure regulation remain unknown but may include differences in body water and sodium regulation. Both estrogen and testosterone receptors are present in the hypothalamus of adult primates and thereby may alter cardiovascular regulation through changes in fluid and sodium balance. In this study, the investigators focused on sex hormone effects specifically related to hypothalamic osmotic regulation of arginine vasopressin (AVP) during hypertonic saline infusion. In response to hypertonic saline infusion, overall body fluid balance is similar between men and women.

Results and Conclusions
However, these investigators found that men had greater plasma AVP sensitivity to an increase in plasma osmolality induced by hypertonic saline infusion, which was associated with an increase in systolic pressure, pulse pressure, plasma cortisol levels, and sodium retention. The mechanism underlying the increased blood pressure and sodium retention observed in men was not clear from the data presented, but these observations indicate a shift in the pressure-natriuresis curve related to differential sensitivity to the renin-angtiotensin system or possibly direct effects on the kidney. In addition, the greater AVP sensitivity to osmotic stimulation may have also caused the greater increase in cortisol and blood pressure during infusion. These findings suggest that a greater osmotic AVP sensitivity may play a role in the greater cardiovascular morbidity in men compared with women.

American Physiological Society. October 2001.

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