Induction of amiloride-sensitive sodium transport in the rat colon by mineralocorticoids

Will, Peter C.; Lebowitz, Jonathan; Hopfer, Ulrich

doi:10.1152/ajprenal.1980.238.4.f261

Cited by 81 publications

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“…In general these observations confirm the results of studies on rat colon in vitro by Will et al (1980), although these authors did not examine the effects of adrenalectomy. They observed that active Na transport by distal colonic epithelium taken from rats exposed to chronic aldosterone stimulation was blocked by amiloride at concentrations similar to those used in the present study.…”

Section: Influence Of Luminal Na Concentration and Ksupporting

confidence: 80%

“…During investigations of various agents on colonic K secretion we observed that variations in aldosterone stimulation considerably modulated the action of amiloride on the colon. A recent report has described the effects of the interaction of amiloride and aldosterone on Na transport in rat colon in vitro (Will, Lebowitz & Hopfer, 1980) and in the present report the results of various studies carried out in vivo particularly to examine the effects of the interaction of amiloride and aldosterone on transepithelial p.d. and K movements will be described.…”

Section: Introductionmentioning

confidence: 76%

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Amiloride sensitivity of the transepithelial electrical potential and of sodium and potassium transport in rat distal colon in vivo.

Edmonds¹

1981

The Journal of Physiology

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Section: Influence Of Luminal Na Concentration and Ksupporting

confidence: 80%

Section: Introductionmentioning

confidence: 76%

Amiloride sensitivity of the transepithelial electrical potential and of sodium and potassium transport in rat distal colon in vivo.

Edmonds¹

1981

The Journal of Physiology

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“…In sodium-depleted rats, however, I sc increased up to 16 NEq.cm-2.h-! (Will et al, 1980). In the distal segment of the distal colon of the GF rats, sodium transport was mainly electrogenic; in the SPF rats, the electrogenic transport was considerably lower.…”

Section: Electrical Measurementsmentioning

confidence: 90%

Sodium transport across the caecal and colonic epithelium of germfree and specific-pathogen free rats

Rösel¹,

Engelhardt²

1996

Reprod. Nutr. Dev.

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Summary ― It was assumed that the enlarged caecum and the accumulation of semiliquid contents in germfree rats is accompanied by changes in sodium absorption. Transepithelial sodium fluxes were studied under Ussing chamber conditions across epithelial sheets of the caecum and colon of germfree (GF) and specific-pathogen free (SPF) rats. Net sodium transport was highest in the proximal colon and in the proximal segment of the distal colon; it was considerably lower in the caecum and in the distal segment of the distal colon. In the caecum and proximal colon of the GF rats, the electroneutral sodium absorption was increased as compared to the SPF rats. In the proximal segments of the distal colon, no differences were seen. In the distal segment of the distal colon, the mainly electroneutral sodium transport in the SPF rats was changed into electrogenic transport in the GF rats. These differences may be due to the increased aldosterone levels of the GF rats.germfree / specific-pathogen free / rat / caecum / colon / sodium transport / in vitro Résumé -Transport du sodium à travers l'épithélium caecal et colique chez des rats axéniques ou sans germes pathogènes. L'hypothèse initiale du présent travail était que des modifications de l'absorption du sodium accompagnent l'élargissement du caecum et l'accumulation de contenus semiliquides chez des rats axéniques. Les flux transépithéliaux de sodium ont été étudiés, dans les conditions de chambre d'Ussing, à travers des parois épithéliales de caecum et de côlon de rats axéniques (GF) ou sans germes pathogènes (SPF). Le transport net du sodium était le plus élevé dans le côlon proximal et dans le segment proximal du côlon distal ; il était considérablement plus faible dans le caecum et dans le segment distal du côlon distal. L'absorption électroneutre du sodium dans le caecum et le côlon proximal était augmentée chez les rats GF par rapport aux rats SFP. Aucune différence n'a été observée dans les segments proximaux du côlon distal. Dans le segment distal du côlon distal, le transport du sodium, surtout électroneutre chez les rats SFP, devenait électrogénique chez les rats GF. Ces différences pourraient être dues aux niveaux accrus d'aldostérone chez les rats GF.

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“…Amiloride, a specific blocker of electrogenic epithelial sodium ion transport has no effect on normal rat colon (Will, Lebowitz & Hopfer, 1980;Cuthbert & Margolius, 1982). However, by feeding rats on a low sodium diet, giving mineralocorticoids or high doses of glucocorticoids, electrogenic sodium transport is induced which is amiloride-sensitive (Binder, 1978;Will, Delisle, Cartright & Hopfer, 1981;Cuthbert & Margolius, 1982).…”

Section: Introductionmentioning

confidence: 99%

Conversion of sodium channels to a form sensitive to cyclic AMP by component(s) from red cells

Cuthbert

Spayne

1983

British J Pharmacology

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1Sodium transport has been measured in the isolated epithelium from colons of male SpragueDawley rats. 2 Sodium transport in colons was induced by pretreating the animals with dexamethasone (6 mg kg-) which caused the appearance of an amiloride-sensitive short circuit current within a few hours. 3 Forskolin, a diterpene, which activates adenylate cyclase, was found to increase the cyclic adenosine monophosphate (cyclic AMP) content of rat colons and also to increase short circuit current at the same time. However, measurements of chloride and sodium fluxes across the epithelium indicated that forskolin activates chloride secretion but has no effect on sodium transport.4 In confirmation of (3) it was found that the amiloride-sensitive short circuit current was unchanged after the short circuit current had been increased by forskolin under a variety of conditions. 5The behaviour of the mammalian colon as indicated in (3) and (4) is unlike that of amphibian sodium transporting epithelia. It is shown that in toad urinary bladder forskolin increases amiloridesensitive short circuit current. 6 Procedures were investigated which might make sodium transport in the mammalian colon sensitive to cyclic AMP. Exposing the apical surface to sonicated suspensions of nucleated red cells (frog, toad and duck), followed by washing, gave preparations with amiloride-sensitive short circuit currents which were increased by forskolin or dibutyryl cyclic AMP. 7 It would appear that the sodium channel in the mammalian colon, unlike that of amphibian tissues, has lost the ability to have its properties modified by cyclic AMP. Incubation of colons with sonicated suspensions of nucleated red cells apparently modifies the tissues such that sodium transport across the tissue becomes sensitive to the nucleotide.

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Induction of amiloride-sensitive sodium transport in the rat colon by mineralocorticoids

Cited by 81 publications

References 0 publications

Amiloride sensitivity of the transepithelial electrical potential and of sodium and potassium transport in rat distal colon in vivo.

Amiloride sensitivity of the transepithelial electrical potential and of sodium and potassium transport in rat distal colon in vivo.

Sodium transport across the caecal and colonic epithelium of germfree and specific-pathogen free rats

Conversion of sodium channels to a form sensitive to cyclic AMP by component(s) from red cells

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