RESUMEN
Fluid and ion transport across biliary epithelium contributes to bile flow. Alterations of this function may explain hepatobiliary complications in cystic fibrosis (CF). We investigated electrogenic anion transport across intact non-CF and CF human gallbladder mucosa in Ussing-type chambers. In non-CF tissues, baseline transmural potential difference (PD), short-circuit current (Isc), and resistance (R) were -2.2 +/- 0.3 mV (lumen negative), 40.7 +/- 7.8 microA/cm2, and 66.5 +/- 9.6 Omega. cm2, respectively (n = 14). The addition of forskolin (10(-5) mol/L) to the apical and basolateral baths and that of adenosine 5'-triphosphate (ATP) (10(-4) mol/L) to the apical bath induced significant increases in Isc by 8.0 +/- 1.4 and 10.3 +/- 1.8 microA/cm2, respectively. Depletion of bathing solutions in Cl- and HCO3- significantly reduced baseline Isc and the forskolin- and ATP-induced increases in Isc. Anion secretion was stimulated by extracellular ATP via P2Y2 purinoceptors, as indicated by the effects of different nucleotides on Isc and on 36Cl efflux in cultured gallbladder epithelial cells. This effect was mediated by cytosolic calcium increase and Ca2+/calmodulin-dependent protein kinase II, as ascertained by using inhibitors. In CF preparations, basal PD and Isc were lower than in non-CF, and the response to forskolin was abolished, whereas the response to ATP was enhanced (P <.05 for all). We conclude that electrogenic anion secretion occurs in human gallbladder mucosa under basal state and is stimulated by an adenosine 3',5'-cyclic monophosphate (cAMP)-dependent pathway mediated by cystic fibrosis transmembrane conductance regulator (CFTR), and by exogenous ATP via a CFTR-independent pathway that is up-regulated in CF and involves P2Y2 purinoceptors and a calcium-dependent pathway.
Asunto(s)
Fibrosis Quística/metabolismo , Vesícula Biliar/metabolismo , Adenosina Trifosfato/fisiología , Adolescente , Adulto , Aniones/metabolismo , Transporte Biológico , Canales de Cloruro/metabolismo , AMP Cíclico/fisiología , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Electrofisiología , Espacio Extracelular/metabolismo , Femenino , Humanos , Técnicas In Vitro , Masculino , Membrana Mucosa/metabolismo , Receptores Purinérgicos P2/metabolismo , Receptores Purinérgicos P2Y2 , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/fisiologíaAsunto(s)
Bovinos/genética , ADN Satélite/genética , Ovinos/genética , Animales , Secuencia de Bases , Escala de Lod , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Recombinación Genética , Alineación de Secuencia , Homología de Secuencia de Ácido Nucleico , Especificidad de la EspecieRESUMEN
DNA extracted from 21 hamster-sheep hybrid cell lines was subjected, after Southern blotting, to hybridization with a type-II alpha 1 collagen genomic probe (COL2A1). The corresponding locus was found to be syntenic with the LDHB-PEPB-TPI-GAPD-LALBA-IGF1 group in sheep.