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- Title
Endogenous and Exogenous female sex hormones and renal handling: effects of sodium loading on plasma volume at rest.
- Authors
Sims, Stacy T.; Rehrer, Nancy J.; Bell, Melanie; Cotter, James D.
- Abstract
This study investigated the effects of an acute sodium load on resting plasma volume and renal mechanisms across the menstrual cycle of endurance-trained women with natural or oral contraceptive pill (OCP) mediated cycles. Twelve women were assigned to one of two groups according to their usage status: 1) oral contraceptive pill (OCP, n = 6, 29 y (SD 6), 59.4 kg (SD 3.2)), or 2) natural cycle (NAT, n = 6, 24 y (5), 61.3 kg (3.6)). The sodium load was administered as a concentrated sodium chloride/citrate beverage (164 mmol Na+-1, 253 mOsmkg H2O-1, 10 ml kg-1 BM) during the last high hormone week of the OCP cycle (HHocp) or late-luteal phase of natural cycle (LUTnat);during the low hormone sugar pill week of OCP (SUGocp) or early follicular phase of natural cycle (FOLnat). Beverage (∼628 ml) was ingested in 7 portions across 60 min. Over the next 4 h, plasma volume (PV) expanded more in the low-hormone phase for both groups: (time-averaged change) SUGocp 6.1 (SD 1.1) and FOLnat and 5.4% (1.2) vs. HHocp 3.9 (0.9) and LUTnat 3.5% (0.8), P = 0.02. AVP sensitivity to sodium loading was lower in this phase (1.63 (0.2) and 1.30 pg ml-1 (0.2) vs. 1.82 (0.3) and 1.57 pg ml-1 (0.5), P = 0.0001), as was plasma aldosterone (∼64% lower, P=0.0001). Thus, PV increased more and renal hormone sensitivity was decreased in the low-hormone menstrual phase following sodium/fluid ingestion, irrespective of OCP usage.
- Publication
FASEB Journal, 2008, Vol 22, p120
- ISSN
0892-6638
- Publication type
Article
- DOI
10.1096/fasebj.22.2_supplement.120