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Sex Differences in the Diurnal Natriuretic Response to a Salt Load in Rats Lacking a Functional ET B Receptor
Author(s) -
Johnston Jermaine,
Mason Jourdan,
Jin Chunhua,
Speed Joshua,
Pollock David
Publication year - 2015
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.29.1_supplement.968.24
Subject(s) - natriuresis , endocrinology , medicine , excretion , period (music) , chemistry , biology , zoology , physics , acoustics
Male rats lacking the ET B receptor (ET B def) exhibit salt‐sensitive hypertension due to impaired renal sodium handling. Given that females generally have a reduced incidence of salt‐sensitive hypertension compared to males, we hypothesized that female ET B def rats are better able to excrete a salt load compared to males. ET B def and genetic control rats of both sexes were implanted with telemetry transmitters to monitor mean arterial pressure (MAP) and given at least a week to recover. Following several days of baseline urine collection in 12 hr light/dark increments, rats were given a single 900µEq Na salt load (NaCl) by oral gavage at the beginning of their active (7pm‐7am, dark) or inactive (7am‐7pm, light) period. Urine was again collected in 12 hr intervals for several more days. We previously showed that ET B def males excrete significantly less salt during the initial 12 hr following an acute salt load whether given at the beginning of the active or inactive period compared to genetic controls, an effect that was more pronounced when the salt load was given prior to the inactive period. ET B def females excreted significantly more salt vs. ET B def males following the acute salt load given during the beginning of the active period (673 ± 111 vs. 320 ± 98µEq Na/12hr, P<0.05) and again showed an improved natriuresis vs. ET B def males following a salt load given at the start of the inactive period (183 ± 60 vs. 50 ± 91µEq Na/12hr). There was no significant effect of the salt loading on MAP in any group, although both male and female ET B def rats had significantly elevated MAP compared to controls. These data show that despite the loss of the ET B receptor, females excrete an acute salt load more efficiently than males.