FUNCTIONAL EXPRESSION OF BASOLATERAL CL- HCO3- EXCHANGE FROM RAT JEJUNUM IN XENOPUS-LAEVIS OOCYTES/

Poly(A)(+) RNA isolated from rat jejunum was injected into Xenopus lae vis oocytes and expression of Cl-/HCO3- antiport was investigated by m eans of Cl-36(-) uptake. Two days after injection of 50 ng of poly(A)( +) RNA, Cl- uptake was significantly increased with respect to water-i njected oocytes. The expressed transport was inhibited by 0.2 mM DIDS, whereas endogenous Cl- uptake was unaffected by this disulphonic stil bene. After sucrose density gradient fractionation, the highest expres sion of DIDS-sensitive Cl- uptake was detected with mRNA size fraction of about 2-4 kb in length. The expressed Cl- uptake can occur against a Cl- concentration gradient and is unaffected by the known Cl- chann el blocker anthracene-9-carboxylic acid. Cl- transport mechanism has p roperties similar to jejunal basolateral Cl-/HCO3- exchange with regar d to Naf dependence. (C) 1998 John Wiley & Sons Ltd.