Indo-1 loaded pancreatic β-cells, isolated from obese hyperglycaemic mice, were studied with respect to cytoplasmic free Ca2+ concentration ([Ca2+]i), efflux of indicator and insulin release. In the absence of glucose there was a continuous efflux of indo-1 which increased upon stimulation with 20 mM of the sugar. The anion exchange inhibitor probenecid reduced both basal efflux of indo-1 and prevented that promoted by glucose. Measurements of [Ca2+]i and insulin release revealed similar results as previously reported with quin-2 and fura-2. Furthermore, probenecid did not influence the [Ca2+]i responses. It is thus possible to reduce efflux of indo-1 probenecid and thereby improve the measurements of [Ca2+]iin pancreatic β-cells.
