Expression of the electrogenic Na+-HCO3-- cotransporter NBCe1 in tumoral insulin-producing BRIN-BD11 cells

Background/aims: The expression of the electrogenic Na + -HCO 3 - -cotransporter NBCe1 was recently documented in rat pancreatic islet B-cells, it being speculated that such a protein participates in the extrusion of bicarbonate generated by the oxidative catabolism of nutrients from insulin-producing cells. Considering the prevalence of a Crabtree effect in tumoral insulin-producing cells, the possible presence of NBCe1 was now investigated in BRIN-BD11 cells, an insulin-producing cell line established by electrofusion of normal pancreatic B-cells with immortalized RINm5F cells. Methods: The possible presence of NBCe1 in BRIN-BD11 cells was investigated by RT-PCR, western blot analysis and immunocytochemistry. The release of insulin and net uptake of 22 Na + were also measured in the BRIN-BD11 cells. Results: RT-PCR, western blot analysis and immunocytochemistry documented the presence of NBCe1 in BRIN-BD11 cells. A reported inhibitor of NBCe1, i.e. tenidap, (50-100 µM), inhibited basal and hypotonicity-induced insulin release from the BRIN-BD11