Protein kinase ϵ dampens the secretory response of model intestinal epithelia during ischemia

• Published in: Surgery 2001-08, Vol.130 (2), p.310-318
• Main Authors: Yoo, James, Nichols, Anthony, Song, J.Cecilia, Mun, Edward C., Matthews, Jeffrey B.
• Format: Article
• Language: English
• Subjects: Biological Transport - drug effects; Biological Transport - physiology; Bryostatins; Carcinogens - pharmacology; Cell Hypoxia - physiology; Cell Line; Chlorides - metabolism; Enzyme Activation - physiology; Enzyme Inhibitors - pharmacology; Humans; Indoles - pharmacology; Intestinal Mucosa - cytology; Intestinal Mucosa - enzymology; Intestinal Mucosa - secretion; Ischemia - metabolism; Isoenzymes - metabolism; Lactones - pharmacology; Macrolides; Maleimides - pharmacology; Mitogens - pharmacology; Protein Kinase C - metabolism; Protein Kinase C-epsilon; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0039-6060; 1532-7361
• DOI: 10.1067/msy.2001.116034

Background. Luminal fluid sequestration and diarrhea are early manifestations of mesenteric ischemia. This can be modeled in vitro with the use of T84 intestinal epithelia, where ischemia induces Cl− secretion with adenosine-mediated autocrine feedback. Protein kinase C (PKC) regulates epithelial transport and, in some organ systems, is involved in the response to ischemic stress. The purpose of this study was to define the role of PKC on epithelial transport during ischemia. Methods. By voltage-current clamp, short-circuit current (Isc) equals Cl− secretion. Ischemic conditions were simulated with the use of a well-established chemical hypoxia protocol. Results. Chemical hypoxia briskly activated Isc. Gö6850, an antagonist of novel and conventional PKC isoforms, markedly enhanced the ischemia-induced Isc response, although Gö6976 (which inhibits only conventional isoforms) had no effect. Rottlerin, a specific inhibitor of PKCδ, did not attenuate ischemic Isc. Both phorbol 12-myristate, 13-acetate and bryostatin-1, which selectively activate PKCϵ in T84 cells, markedly attenuated the Isc response to ischemia. Both agents also inhibited the Isc response to exogenous adenosine. Conclusions. PKC (likely the novel ϵ isoform) in intestinal epithelia modulates ischemia-induced alterations in ion transport. Inhibition of PKCϵ exaggerates the secretory response that is induced by ischemia and by authentic adenosine; conversely, augmented activation of PKCϵ inhibits secretion. Manipulation of PKCϵ could limit luminal fluid sequestration during mesenteric ischemia. (Surgery 2001;130:310-8.)