Open AccessEffects of sex and menstrual cycle on volume-regulatory responses to 24-h fluid restriction
Author(s) -
Gabrielle E.W. Giersch,
Abigail T. Colburn,
Margaret C. Morrissey,
Cody R. Butler,
Michaela L. Pruchnicki,
Stavros A. Kavouras,
Nisha Charkoudian,
Douglas J. Casa
Publication year - 2020
Publication title -
american journal of physiology. regulatory, integrative and comparative physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.266
H-Index - 175
eISSN - 1522-1490
pISSN - 0363-6119
DOI - 10.1152/ajpregu.00173.2020
Subject(s) - copeptin , medicine , urine , endocrinology , follicular fluid , menstrual cycle , plasma osmolality , urinalysis , urine osmolality , dehydration , hormone , vasopressin , chemistry , biology , embryo , biochemistry , oocyte , microbiology and biotechnology
Reproductive hormones have significant nonreproductive physiological effects, including altering fluid regulation. Our purpose was to explore the impact of sex and menstrual cycle (MC) phase on volume-regulatory responses to 24-h fluid restriction (24-h FR). Participants (men: n = 12, 20 ± 2 yr; women: n = 10, 20 ± 1 yr) were assigned two randomized and counterbalanced fluid prescriptions [Euhy: euhydrated, urine specific gravity (USG) < 1.020; Dehy: 24-h FR, USG > 1.020]. Men completed both (MEuhy, MDehy), while women completed both in the late-follicular ( days 10-13 ; FDehy, FEuhy) and midluteal ( days 18-22 ; LDehy, LEuhy) phases. We measured body mass, plasma and urine osmolality (P osm , U osm ), urine specific gravity (USG), urine color (U col ), and serum copeptin; 24-h FR yielded mild dehydration without influence of sex or MC ( P > 0.05). Copeptin increased in men following Dehy (pre: 8.2 ± 5.2, post: 15.8 ± 12.6, P = 0.04) but not in women (FDehy pre: 4.3 ± 1.6, post: 10.5 ± 6.9, P = 0.06; LDehy pre: 5.6 ± 3.5, post: 10.4 ± 6.2, P = 0.16). In FDehy, P osm increased following FR (pre: 288 ± 2, post: 292 ± 1, P = 0.03) but not in men (pre: 292 ± 3, post: 293 ± 2, P = 0.46). No MC differences were observed between body mass loss, P osm , U osm , USG, and copeptin ( P > 0.05). These results suggest that volume-regulatory responses to 24-h FR were present in men but not in women, without apparent effects of the menstrual cycle.