Plasma arginine vasopressin (AVP) concentration as a function of plasma osmolality during 120 min of hypertonic (3% NaCl) saline infusion during suppression of reproductive function with a gonadotropin-releasing hormone agonist (GnRHa), with (dashed line) and without (solid line)17 β-estradiol administration (4,23,26). Note the high estrogen condition shifted the P[AVP]-POsm curve to the left relative to the GnRH agonist-alone. (Reprinted from Stachenfeld, N.S., and D.L. Keefe. Estrogen effects on osmotic regulation of AVP and fluid balance. Am. J. Physiol. Endocrinol. Metab. 283:E711–E721, 2002. Copyright © 2002 The American Physiological Society. Used with permission.)