title: Expression of rat renal Na+HCO3-cotransporter in Xenopus laevis oocytes.
abstract: The goal of this study was to determine whether Na+HCO3- cotransport from rat renal cortex can be functionally expressed in Xenopus laevis oocytes. Using a two electrode voltage-clamp device, HCO(3-)-dependent currents were determined as the difference in current measured in a nominally HCO(3-)-free buffer, pH 7.5 and a buffer with 30 mmol/l HCO3-, pCO2 5.33 kPa, pH 7.5. The size of renal cortex mRNA required to express maximum HCO(3-)-dependent current was 2-3 kb. The expressed current depended on Na+ and was sensitive to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and acetazolamide (each 1 mmol/l), inhibitors known to block the native Na(+)HCO3- cotransporter in several tissues including rat proximal tubule. Water-injected oocytes did not show any measurable response either to increased HCO3- nor to Na(+)-free perfusion or to the inhibitors, indicating the absence of an endogenous electrogenic HCO3-transporter. Our data indicate that the rat renal mRNA of 2-3 kb size contains the message for the Na+HCO3-cotransporter.
authors.affiliation: Zentrum Physiologie und Pathophysiologie, Göttingen, Germany.
authors.forename: B C
authors.initials: BC
authors.lastname: Burckhardt
authors.forename: P
authors.initials: P
authors.lastname: Thelen
authors.forename: G
authors.initials: G
authors.lastname: Burckhardt
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D015870:Gene Expression / Q000235:genetics; D017136:Ion Transport; D007672:Kidney Cortex / Q000502:physiology*; D008297:Male; D009865:Oocytes / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D017693:Sodium Bicarbonate / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D017693:Sodium Bicarbonate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid