Abraham, Andrew J.Duvall, Ethan S.Leese, CallumAbraham, KirstinLe Roux, ElizabethRiond, BarbaraOrtmann, SylviaTerranova, MelissaLeese, GrahamBailey, Matthew A.Clauss, Marcus2026-03-192026-03-192026-02Abraham, A.J., Duvall, E.S., Leese, C. et al. Preliminary evidence of extrarenal sodium storage in a large mammal: implications for comparative physiology and hypertension research. Pflügers Archiv - European Journal of Physiology 478, 25: 1-13 (2026). https://doi.org/10.1007/s00424-026-03155-2.0031-6768 (print)1432-2013 (online)10.1007/s00424-026-03155-2http://hdl.handle.net/2263/109079DATA AVAILABILITY : Data associated with this paper is available at: https://doi.org/10.6084/m9.figshare.29064485.Under conditions of dietary sodium (Na+) excess, the kidneys may fail to adequately excrete Na+, potentially compromising blood pressure homeostasis. Body tissues, such as skin, can offer sites of short-term extrarenal Na+ storage and previous research has shown that this can help guard against hypertension in small mammals (e.g., rodents). Large mammals have relatively greater Na+ storage potential, but whether extrarenal Na+ storage occurs for this group is unknown. Here, we report preliminary evidence of extrarenal Na+ storage in cattle. We provided a large pulse-dose of NaCl to four cattle (body mass: ~720 kg) and measured excretion of Na+ and potassium (K+) in urine and faeces for a period of 7-days. Following NaCl administration, Na+ excretion spiked in both urine and faeces for ~ 48 h before returning to baseline measurements. After ~ 96 h, however, Na+ excretion increased again; a consistent physiological phenomenon across all individuals studied. We did not observe a pattern in urinary K+ excretion, indicating that the mechanism of Na+ storage does not appear to involve exchange for K+. However, faecal K+ excretion was reciprocal to that of Na+, presumably reflecting exchange of Na+/K+ across the walls of the large intestine. We infer that during the initial period of Na+ stress, short-term extrarenal Na+ storage occurred and the stored Na+ was later released only when the body had returned to Na+ homeostasis. Additional experiments are required to understand how patterns of Na+ regulation changes across body sizes and the specific body compartments involved. Cattle may be a useful model system for examining the impact of high Na+ intake in mammals larger than humans.en© The Author(s) 2026. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License.AllometryCattleSodiumRenalPotassiumHypertensionHomeostasisArticle