[Ca2+]i oscillations from internal stores sustain exocytic secretion from the chromaffin cells of the rat.
A large (65%) fraction of in vitro cultured rat chromaffin cells exhibit spontaneous [Ca2+]i oscillations, and the rest can be recruited to oscillate by appropriate stimulations. Based on fura-2 single cell [Ca2+]i measurements, evidence is provided that these oscillations originate, via the activation of Ca(2+)-induced Ca(2+)-release, from intracellular Ca2+ stores in rapid equilibrium with extracellular Ca2+. By combining [Ca2+]i measurements with a specific plaque secretion assay we demonstrate that oscillating cells exhibit a spontaneous exocytic secretory activity whereas the cells with stable [Ca2+]i do not. [Ca2+]i oscillations appear therefore to account for the high unstimulated catecholamine release, an activity typical of the chromaffin cells of the rat.
Malgaroli
A
A
Department of Pharmacology, CNR Center of Cytopharmacology, University of Milano, Italy.
Meldolesi
J
J
D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D053379:Chromogranin A; D002864:Chromogranins / Q000032:analysis; D003600:Cytosol / Q000378:metabolism; D005089:Exocytosis; D016257:Fura-2; D066298:In Vitro Techniques; D007700:Kinetics; D051381:Rats
D053379:Chromogranin A; D002864:Chromogranins; D002118:Calcium; D016257:Fura-2