title: Kappa-opioid receptor stimulation increases the expression of Na+-H+ exchange gene in the heart.
abstract: Kappa-opioid receptor (OR) stimulation increases intracellular pH (pHi) via activating the Na+-H+ exchange (NHE). In the present study, we determined the expression of the gene of NHE1, the predominant NHE isoform in the heart, and intracellular pH (pHi) upon kappa-OR stimulation in the rat heart. We found that 1 microM U50,488H (trans-3,4-dichloro-N-methyl-N-(2-(1 pyrrolidinyl)cyclohexyl)benzeneacetamide), a selective kappa-OR agonist, increased the expression of the NHE1 gene. We also found that U50,488H dose-dependently increased pHi in the heart. The effects were abolished by 1 microM nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, indicating that the events were kappa-OR mediated. The effects on both NHE1 gene expression and pHi were also abolished by 5 microM chelerythrine and 5 microM BSM (bisyndolylmaleimide), protein kinase C (PKC) inhibitors, indicating that PKC mediated the actions. In addition, the effect of U50,488H on pHi was blocked by 10 microM EIPA (ethylisopropyl amiloride), a NHE1 inhibitor, indicating that NHE1 also mediated the action of U50,488H. The present study provides evidence for the first time that kappa-OR stimulation increased the NHE1 gene expression in the heart via a PKC dependent pathway. Kappa-OR stimulation also increases pHi via PKC and NHE in the heart.
authors.affiliation: Department of Physiology and Institute of Cardiovascular Science and Medicine, Faculty of Medicine, The University of Hong Kong, China.
authors.forename: T
authors.initials: T
authors.lastname: Gan
authors.forename: J
authors.initials: J
authors.lastname: Pei
authors.forename: I
authors.initials: I
authors.lastname: Chan
authors.forename: T
authors.initials: T
authors.lastname: Wong
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology; D000818:Animals; D005786:Gene Expression Regulation; D006863:Hydrogen-Ion Concentration; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*
chemical_list: D017473:Receptors, Opioid, kappa; D017923:Sodium-Hydrogen Exchangers; C051844:norbinaltorphimine; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D011493:Protein Kinase C