Differential regulation of large conductance K+ (BK) channel mediated K+ secretion in proximal and distal colon by aldosterone

• DOI: 10.1096/fasebj.30.1_supplement.1223.15
• Publication Date: 2023-11-26T16:34:18Z
• Authors: Andrew J Nickerson; Kyla M Galbreath; Vazhaikkurichi M ...
• Keywords: Apical membrane; Ussing chamber; Sodium–hydrogen antiporter

Aldosterone (“aldo”) differentially regulates electrolyte transport processes, as it stimulates Na‐H exchanger isoform‐3 (NHE3) mediated electroneutral Na + absorption, and down‐regulates NHE3 induces epithelial channel (ENaC) electrogenic absorption in proximal distal segments of rat colon, respectively. Electrogenic active K secretion is present while H , ‐ATPase colon normal colon. Aldo enhances expression Mucosal ortho‐vanadate (VO 4 ; p‐type ATPase inhibitor) unmasked the “aldo” induced BK It not known whether also Studies were, therefore, initiated to identify activates rats were generated by feeding Na‐free diet for 6 – 7 days. 86 Rb (K surrogate) fluxes measured muscularis stripped mounted under voltage clamp condition Ussing chamber. serosal (m‐s) mucosal (s‐m) measured, net calculated subtracting s‐m from m‐s. Net positive negative represent secretion, significantly enhanced (−0.25 ± 0.05 vs −0.47 0.12 μEq/h.cm2; p < 0.05). Forskolin (FSK, adenylate kinase activator) stimulated both (0.25 0.42 0.09 0.05) aldo (0.47 1.30 μEq/h.cm2). iberiotoxin (IbTX, inhibited FSK‐stimulated normal, but did affect In contrast IbTX, charybdotoxin [CTX; intermediate (IK) blocker) completely proximal. We conclude that FKS via: 1) IK channels colon; 2) entirely through Support or Funding Information This work was supported NIH NIDDK Grant 1006856R VMR.