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Endogenous and Exogenous female sex hormones and renal handling: effects of sodium loading on plasma volume at rest
Author(s) -
Sims Stacy T,
Rehrer Nancy J,
Bell Melanie,
Cotter James D
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.2_supplement.120
Subject(s) - endocrinology , medicine , menstrual cycle , sodium , hormone , luteal phase , follicular phase , chemistry , aldosterone , plasma volume , organic chemistry
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+•L‐1, 253 mOsm•kg 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 â^†6.1 (SD 1.1) and FOLnat and 5.4% (1.2) vs. HHocp â^†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.