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Internal sodium balance in DOCA-salt rats: a body composition study [Erratum in: Am J Physiol Renal Physiol. vol 290, pg F561-F562, 2006]

Item Type:Article
Title:Internal sodium balance in DOCA-salt rats: a body composition study [Erratum in: Am J Physiol Renal Physiol. vol 290, pg F561-F562, 2006]
Creators Name:Titze, J. and Bauer, K. and Schafflhuber, M. and Dietsch, P. and Lang, R. and Schwind, K.H. and Luft, F.C. and Eckardt, K.U. and Hilgers, K.F.
Abstract:The idea that Na+ retention inevitably leads to water retention is compelling; however, were Na+ accumulation in part osmotically inactive, regulatory alternatives would be available. We speculated that in DOCA-salt rats Na+ accumulation is excessive relative to water. Forty female Sprague-Dawley rats were divided into four subgroups. Groups 1 and 2 (controls) received tap water or 1% saline (salt) for 5 wk. Groups 3 and 4 received subcutaneous DOCA pellets and tap water or salt. Na+, K +, and water were measured in skin, bone, muscle, and total body by desiccation and consecutive dry ashing. DOCA-salt led to total body Na + excess (0.255 ± 0.022 vs. 0.170 ± 0.010 mmol/g dry wt; P < 0.001), whereas water retention was only moderate (0.685 ± 0.119 vs. 0.648 ± 0.130 ml/g wet wt; P < 0.001). Muscle Na+ retention (0.220 ± 0.029 vs. 0.145 ± 0.021 mmol/g dry wt; P < 0.01) in DOCA-salt was compensated by muscle K+ loss, indicating osmotically neutral Na+/K+ exchange. Skin Na+ retention (0.267 ± 0.049 vs. 0.152 ± 0.014 mmol/g dry wt; P < 0.001) in DOCA-salt rats was not balanced by K+ loss, indicating osmotically inactive skin Na+ storage. We conclude that DOCA-salt leads to tissue Na+ excess relative to water. The relative Na + excess is achieved by two distinct mechanisms, namely, osmotically inactive Na+ storage and osmotically neutral Na+ retention balanced by K+ loss. This "internal Na+ escape" allows the maintenance of volume homeostasis despite increased total body Na+.
Keywords:Escape, Hypertension, Hypertensive Rats, Mineralocorticoid, Sodium Storage, Animals, Rats
Source:American Journal of Physiology Renal Physiology
ISSN:0363-6127
Publisher:American Physiological Society (U.S.A.)
Volume:289
Number:4
Page Range:F793-F802
Date:24 May 2005
Official Publication:https://doi.org/10.1152/ajprenal.00096.2005
PubMed:View item in PubMed

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