Premium
Activation of K and Cl secretion in guinea pig distal colon requires phospholipase C (PLC) and protein kinase C (PKC)
Author(s) -
Liao Tianjiang,
Halm Susan,
Halm Dan
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a348-c
Subject(s) - protein kinase c , secretion , rottlerin , staurosporine , phospholipase c , chemistry , stimulation , microbiology and biotechnology , endocrinology , medicine , biology , signal transduction
Secretagogues epinephrine (epi), prostaglandinE 2 (PGE 2 ) and carbachol (CCh) stimulate distinct rates of Cl − and K + secretion in guinea pig distal colonic epithelium, with the ratio of K + to Cl − secretion ranging from primarily K + secretion with epi, through equal rates with PGE 2 , to primarily Cl − secretion with CCh+PGE 2 . Transepithelial current (I sc ) and conductance (G t ) were measured during inhibition of PLC and PKC. PLC inhibition with ET‐18‐OCH 3 [100μM] or D609 [100μM] reduced epi‐stimulated K + secretory I sc . Only D609 inhibited PGE 2 and CCh+PGE 2 stimulated I sc , with a large transient (~3min) I sc remaining with CCh+PGE 2 . PLC inhibitor U73122 [10μM] did not alter these secretory responses. Inhibiting DAG‐lipase with RHC‐80267 [50μM] stimulated K + secretory I sc , but did not augment maximal K + secretory capacity. Epi‐stimulated I sc was reduced by PKC inhibitors staurosporine [300nM] or rottlerin [100μM], but not Gö6850 [3μM]. PGE 2 ‐stimulated I sc was not reduced by these PKC inhibitors. PKC‐ε was detected by immunoblot in cytosolic and both Triton‐soluble and insoluble membrane fractions. PKC‐δ was detected primarily in the insoluble membrane fraction. PGE 2 stimulation shifted PKC‐ε toward the soluble membrane fraction. Immunofluorescence localized PKC‐δ and PKC‐ε diffusely to the cytoplasmic space of crypt and surface epithelial cells, with PKC‐δ most prominent in goblet cells. PGE 2 stimulation shifted PKC‐ε toward crypt cell borders. These results support a secretory signaling pathway involving DAG release by PLC leading to K + and Cl − secretion, likely by PKC activation. [NIH, DK65845]