Role of protein kinase C in aldosterone-induced non-genomic inhibition of basolateral potassium channels in human colonic crypts.
Aldosterone produces rapid, non-genomic, inhibition of basolateral intermediate conductance K(+) (IK(Ca)) channels in human colonic crypt cells but the intracellular second messengers involved are unclear. We therefore evaluated the role of protein kinase C (PKC) in aldosterone's non-genomic inhibitory effect on basolateral IK(Ca) channels in crypt cells from normal human sigmoid colon. Patch clamp studies revealed that in cell-attached patches, IK(Ca) channel activity decreased progressively to 38+/-8% (P<0.001) of the basal value 10 min after the addition of 1 nmol/L aldosterone, and decreased further to 23+/-6% (P<0.02) of the basal value 5 min after increasing the aldosterone concentration to 10 nmol/L. Pre-incubation of crypts with 1 micromol/L chelerythrine chloride or 1 micromol/L Gö 6976 (PKC inhibitors) prevented the inhibitory effect of aldosterone. Conversely, channel activity decreased to 60+/-9% (P<0.02) of the basal value 10 min after the addition of 500 nmol/L PMA (a PKC activator), whereas 4alpha-PMA (an inactive ester) had no effect. When aldosterone (10 nmol/L) and PMA were added together, IK(Ca) channel activity was inhibited to the same extent as with aldosterone alone. These results indicate that aldosterone's non-genomic inhibitory effect on the macroscopic basolateral K(+) conductance in human colonic crypts reflects PKC-mediated inhibition of IK(Ca) channels.
Bowley
Kate A
KA
Institute for Molecular Medicine, St. James's University Hospital, Leeds LS9 7TF, UK.
Linley
John E
JE
Robins
Gerrard G
GG
Kopanati
Shashikala
S
Hunter
Malcolm
M
Sandle
Geoffrey I
GI
D000328:Adult; D000450:Aldosterone / Q000494:pharmacology*; D000470:Alkaloids / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D053119:Benzophenanthridines / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051571:Protein Kinase C-alpha / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D000970:Antineoplastic Agents; D053119:Benzophenanthridines; D002273:Carcinogens; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; D026902:Potassium Channel Blockers; D000450:Aldosterone; C016299:chelerythrine; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha; D013755:Tetradecanoylphorbol Acetate