Journal
JOURNAL OF APPLIED PHYSIOLOGY
Volume 98, Issue 6, Pages 1991-1997Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.00031.2005
Keywords
extracellular fluid regulation; gonadotropin-releasing hormone antagonist; ganirelix acetate; blood volume; estrogen
Categories
Funding
- NHLBI NIH HHS [R01 HL 62240, R01 HL 071159] Funding Source: Medline
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Adequate plasma volume (PV) and extracellular fluid (ECF) volume are essential for blood pressure and fluid regulation. We tested the hypotheses that combined progesterone (P-4)estrogen (E-2) administration would increase ECF volume with proportional increases in PV, but that P4 would have little independent effect on either PV or ECF volume. We further hypothesized that this P-4- E-2-induced fluid expansion would be a function of renin-angiotensin-aldosterone system stimulation. We suppressed P-4 and E-2 with a gonadotropin-releasing hormone ( GnRH) antagonist in eight women ( 25 +/- 2 yr) for 16 days; P-4 ( 200 mg/day) was added for days 5 - 16 ( P-4) and 17 beta-estradiol ( 2 x 0.1 mg/day patches) for days 13 - 16 (P-4- E-2). On days 2 ( GnRH antagonist), 9 ( P-4), and 16 ( P-4- E-2), we estimated ECF and PV. To determine the rate of protein and thus water movement across the ECF, we also measured transcapillary escape rate of albumin. In P-4, P[P-4] increased from 2.5 +/- 1.3 to 12.0 +/- 2.8 ng/ml ( P < 0.05) with no change in P-[E2] ( 21.5 +/- 9.4 to 8.6 +/- 2.0 pg/ml). In P-4- E-2, plasma concentration of P-4 remained elevated ( 11.3 +/- 2.7 ng/ml) and plasma concentration of E-2 increased to 254.1 +/- 52.7 pg/ml ( P < 0.05). PV increased during P-4 ( 46.6 +/- 2.5 ml/ kg) and P-4- E-2 (48.4 +/- 3.9 ml/kg) compared with GnRH antagonist ( 43.3 +/- 3.2 ml/ kg; P < 0.05), as did ECF ( 206 +/- 19, 244 +/- 25, and 239 +/- 27 ml/ kg for GnRH antagonist, P-4, and P-4- E-2, respectively; P < 0.05). Transcapillary escape rate of albumin was lowest during P-4- E-2 (5.8 +/- 1.3, 3.5 +/- 1.7, and 2.2 +/- 0.4%/ h for GnRH antagonist, P-4, and P-4- E-2, respectively; P < 0.05). Serum aldosterone increased during P-4 and P-4- E-2 compared with GnRH antagonist ( 79 +/- 17, 127 +/- 13, and 171 +/- 25 pg/ml for GnRH antagonist, P-4, and P-4- E-2, respectively; P < 0.05), but plasma renin activity and plasma concentration of ANG II were only increased by P-4- E-2. This study is the first to isolate P-4 effects on ECF; however, the mechanisms for the ECF and PV expansion have not been clearly defined.
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