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Considering the insufficient supply of long-chain polyunsaturated [omega]-3 fatty acids often prevailing in Western populations, this report deals mainly with alterations of [Ca.sup.2+] fluxes and [Ca.sup.2+]-dependent insulin secretory events in isolated pancreatic islets from [omega]-3-depleted rats. In terms of [sup.45][Ca.sup.2+] handling, the islets from [omega]-3-depleted rats, compared with those from normal animals, displayed an unaltered responsiveness to an increase in extracellular [K.sup.+] concentration, a lower inflow rate and lower fractional outflow rate of the divalent cation, and higher [sup.45][Ca.sup.2+]-labeled cellular pool(s) at isotopic equilibrium. The latter anomaly was corrected 120 min after intravenous injection of a novel medium-chain triglyceride-fish oil (MCT:FO) emulsion, distinct from a control [omega]-3-poor MCT-olive oil (MCT:OO) emulsion. At 8.3 mM D-glucose, insulin release was higher in islets from [omega]-3-depleted rats vs. control animals, coinciding with a higher cytosolic [Ca.sup.2+] concentration. The relative magnitude of the increase in insulin output attributable to a rise in D-glucose as well as extracellular [Ca.sup.2+] or [K.sup.2+] concentration, to the absence vs. presence of verapamil and to the presence vs. absence of extracellular [Ca.sup.2+], theophylline, phorbol 12-myristate 13-acetate, or [Ba.sup.2+], was always more pronounced in islets from [omega]-3-depleted rats injected with the MCT:OO compared with the MCT:FO emulsion. A comparable situation prevailed when comparing islets from noninjected [omega]-3-depleted and normal rats. In light of these and previous findings, we propose that an impairment of [Na.sup.+], [K.sup.+]-ATPase activity plays a major, although not an exclusive, role in the perturbation of [Ca.sup.2+] fluxes and [Ca.sup.2+]-dependent secretory events in the islets from [omega]-3-depleted rats. long-chain polyunsaturated [omega]-3 fatty acid-depleted rats; calcium fluxes; pancreatic islets doi:10.1152/ajpendo.00455.2005