Effect of NPPB on chloride (Cl-) transport in distal colon of potassium (K+) adapted rats.

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  • Additional Information
    • Source:
      Publisher: Blackwell Scientific Publications Country of Publication: England NLM ID: 0370362 Publication Model: Print Cited Medium: Print ISSN: 0001-6772 (Print) Linking ISSN: 00016772 NLM ISO Abbreviation: Acta Physiol Scand Subsets: MEDLINE
    • Publication Information:
      Publication: Oxford : Blackwell Scientific Publications
      Original Publication: Stockholm.
    • Subject Terms:
      Chloride Channels/*metabolism ; Chlorides/*metabolism ; Colon/*metabolism ; Nitrobenzoates/*pharmacology ; Potassium/*metabolism; Adaptation, Physiological ; Amiloride/pharmacology ; Animals ; Cell Membrane Permeability ; Chloride Channels/drug effects ; Colon/drug effects ; Cyclic AMP/metabolism ; Ion Transport/drug effects ; Male ; Rats ; Rats, Wistar
    • Abstract:
      Secondary hyperaldosteronism enhances the rate of K secretion in distal colon, at least in part, through the stimulation of Na(+)-K(+)-Cl- cotransport across the basolateral membrane. To maintain a constant intracellular Cl- activity an increase in Cl- transport out of the cell must be assumed. We explored, under amiloride 10(-4) M and short circuited conditions, conductive pathways for Cl- exit in the distal colon of K(+)-adapted rats by means of a putative Cl- channel blocker, NPPB (5-nitro-2(3-phenyl-propylamino-benzoate. Results prior to NPPB showed an increase in JClms after K+ loading from 5.84 +/- 0.66 to 8.33 +/- 0.86 and JClsm from 4.77 +/- 0.55 to 8.16 +/- 0.96 microEq h-1 cm-2 (P < 0.001), when compared with controls. Net fluxes were not different between groups. Luminal NPPB in K+ adaptation resulted in a decrease of JClsm, from 7.85 +/- 1.5 to 6.69 +/- 1.5 microEq h-1 cm-2 (P < 0.05). There were no changes in both unidirectional Cl- fluxes in controls under luminal NPPB and in potential difference (V) and short-circuit current (Isc) under any condition. Finally, K+ adaptation resulted in an increase of luminal cyclic AMP (cAMP) concentration (0.09 +/- 0.02 to 0.20 +/- 0.03 pmol 100 microliters -1, P < 0.005), when compared with control rats. The data may suggest a transcellular recycling of Cl- and an activated NPPB inhibitable serosal to mucosal Cl- pathway on luminal membrane in the K+ adapted state, possibly mediated by an increase in cAMP production.
    • Accession Number:
      0 (Chloride Channels)
      0 (Chlorides)
      0 (Nitrobenzoates)
      3A35O9G3YZ (5-nitro-2-(3-phenylpropylamino)benzoic acid)
      7DZO8EB0Z3 (Amiloride)
      E0399OZS9N (Cyclic AMP)
      RWP5GA015D (Potassium)
    • Publication Date:
      Date Created: 19940501 Date Completed: 19940830 Latest Revision: 20131121
    • Publication Date:
      20231215
    • Accession Number:
      10.1111/j.1748-1716.1994.tb09719.x
    • Accession Number:
      8048335