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Salt‐ And Angiotensin Ii‐Dependent Variations In Amiloride‐Sensitive Rectal Potential Difference In Mice
Author(s) -
Wang Qing,
Horisberger JeanDaniel,
Maillard Marc,
Brunner Hans R,
Rossier Bernard C,
Burnier Michel
Publication year - 2000
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2000.03204.x
Subject(s) - amiloride , endocrinology , medicine , epithelial sodium channel , chemistry , angiotensin ii , renal sodium reabsorption , sodium , reabsorption , receptor , organic chemistry
SUMMARY 1. In the rectum and distal nephron, sodium reabsorption is mediated by the amiloride‐sensitive epithelial sodium channel (ENaC). The ENaC‐mediated sodium transport is electrogenic and creates an amiloride‐sensitive transepithelial potential difference (PD). 2. We have evaluated the salt‐ and angiotensin (Ang)II‐dependent variations in amiloride‐sensitive rectal PD in mice and assessed their relationship with renal sodium handling. 3. Rectal PD was measured in vivo in mice maintained on a medium‐, low‐ or high‐sodium diet. On a medium‐salt diet, the mean ( ± SEM) amiloride‐sensitive PD was larger in the afternoon than in the morning (–26.1 ± 0.9 and –11.2 ± 0.7 mV, respectively; P = 0.001), indicating a circadian cyclicity. Rectal PD increased on a low‐sodium diet and decreased on a high‐sodium diet. 4. Amiloride‐sensitive rectal PD correlated significantly with the urinary Na + /K + ratio ( P < 0.001) and with sodium reabsorption in the distal nephron as measured by the lithium clearance technique ( P < 0.001). 5. In mice treated with an AngII AT 1 receptor antagonist, amiloride‐sensitive rectal PD was increased in the afternoon compared with controls (–32.8 ± 2.0 vs –24.4 ± 0.9, respectively; P < 0.001). 6. At high doses, AngII decreased the amiloride‐sensitive rectal PD and this effect was blunted by an AT 1 receptor antagonist. 7. These results show the presence of a salt‐dependent daily cyclicity of sodium transport in the mouse rectum that follows circadian changes in sodium handling in the distal nephron. Angiotensin II appears to modulate this diurnal pattern of rectal amiloride‐sensitive sodium transport.