caa a22 4500 465826628 CHVBK 20180323112151.0 cr unu---uuuuu 170327e19900701xx s 000 0 eng 10.1007/BF01075669 doi (NATIONALLICENCE)springer-10.1007/BF01075669 Aldosterone regulates paracellular pathway resistance in rabbit distal colon [Elektronische Daten] [Bernhard Hoffmann, Isolde Nagel, Wolfgang Clauss] Summary: Regulation of the paracellular pathway in rabbit distal colon by the hormone aldosterone was investigated in vitro in Ussing chambers by means of transepithelial and microelectrode techniques. To evaluate the cellular and paracellular resistances an equivalent circuit analysis was used. For the analysis the apical membrane resistance was altered using the antibiotic nystatin. Under control conditions two groups of epithelia were found, each clearly dependent on the light: dark regime. Low-transporting epithelia (LT) were observed in the morning and high-transporting epithelia (HT) in the afternoon. Na+ transport was about 3-fold higher in HT than in LT epithelia. Incubating epithelia of both groups with 0.1 μmol·1-1 aldosterone on the serosal side nearly doubled in LT epithelia the short circuit current and transepithelial voltage but the transepithelial resistance was not influenced. Maximal values were reached after 4-5 h of aldosterone treatment. In HT epithelia due to the effect of aldosterone all three transepithelial parameters remained constant over time. Evaluation of the paracellular resistance revealed a significant increase after aldosterone stimulation in both epithelial groups. This increase suggests that tight junctions might have been regulated by aldosterone. The hormonal effect on electrolyte transport was also dependent on the physiological state of the rabbit colon. Since net Na+ absorption in distal colon is, in addition to transcellular absorption capacity, also dependent on the permeability of the paracellular pathway, the regulation of tight junctions by aldosterone may be a potent mechanism for improving Na+ absorption during hormone-stimulated ion transport. Springer-Verlag, 1990 Rabbit nationallicence Distal colon nationallicence Aldosterone nationallicence Socium absoption nationallicence Paracellular pathway nationallicence Nystatin nationallicence V t : transepithelial potential difference (mV) nationallicence R t : transepithelial resistance (Ω·cm2) nationallicence G t : transepithelial conductance (mS·cm-2) nationallicence Isc : calculated short circuit current (μA·cm-2) nationallicence V a : apical membrane potential difference (mV) nationallicence V bl : basolateral membrane potential difference (mV) nationallicence α : voltage divider ratio nationallicence R a : apical membrane resistance (Ω·cm2) nationallicence R bl : basolateral membrane resistance (Ω·cm2) nationallicence R c : cellular resistance (Σ of apical and basolateral resistance) (Ω·cm2) nationallicence R p : resistance of the paracellular pathway (Ω·cm2) nationallicence G a : apical membrane conductance (mS·cm-2) nationallicence G bl : basolateral membrane conductance (mS·cm-2) nationallicence G p : paracellular conductance (mS·cm-2) nationallicence G t : transepithelial conductance (mS·cm-2) nationallicence HT contr : high transporting control epithelia nationallicence LT contr : low transporting control epithelia nationallicence HT aldo : aldosterone incubated high transporting epithelia nationallicence LT aldo : aldosterone incubated low transporting epithelia nationallicence Hoffmann Bernhard Institut für Veterinärphysiologie, Freie Universität Berlin, Koserstr. 20, 1000, Berlin 33, Federal Republic of Germany aut Nagel Isolde Institut für Veterinärphysiologie, Freie Universität Berlin, Koserstr. 20, 1000, Berlin 33, Federal Republic of Germany aut Clauss Wolfgang Institut für Veterinärphysiologie, Freie Universität Berlin, Koserstr. 20, 1000, Berlin 33, Federal Republic of Germany aut Journal of Comparative Physiology B Springer-Verlag 160/4(1990-07-01), 381-388 0174-1578 160:4<381 1990 160 360 https://doi.org/10.1007/BF01075669 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01075669 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hoffmann Bernhard Institut für Veterinärphysiologie, Freie Universität Berlin, Koserstr. 20, 1000, Berlin 33, Federal Republic of Germany aut NATIONALLICENCE 700 1- Nagel Isolde Institut für Veterinärphysiologie, Freie Universität Berlin, Koserstr. 20, 1000, Berlin 33, Federal Republic of Germany aut NATIONALLICENCE 700 1- Clauss Wolfgang Institut für Veterinärphysiologie, Freie Universität Berlin, Koserstr. 20, 1000, Berlin 33, Federal Republic of Germany aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 160/4(1990-07-01), 381-388 0174-1578 160:4<381 1990 160 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer