Microspectrofluorometry and video imaging techniques were used to study and to compare the changes in intracellular calcium concentrations ([Ca2+]i) of individual Fura-2 loaded Spisula oocytes treated with serotonin (5-hydroxytryptamine, 5-HT) or tricyclic antidepressants. In the present study, we showed that 5-HT increased [Ca2+]i in freshly isolated Spisula oocytes suspended in artificial sea water. In the absence of extracellular Ca2+, 5-HT did not influence [Ca2+]i. Stimulation of [Ca2+]i by 5-HT was blocked by calcium channel blocker, e.g. verapamil, and by tricyclic antidepressants. These observations combined with our previous results on the effects of 5-HT, tricyclic antidepressants and verapamil on calcium uptake suggest that the increase in [Ca2+]i induced by 5-HT results from an influx of extracellular calcium through calcium channels, which can be blocked by tricyclic antidepressants. The use of the Fura-2 imaging technique allowed single-cell measurements and defined changes induced by 5-HT in [Ca2+]i which is the net result of calcium uptake and release of intracellular calcium from storage sites in individual Spisula oocytes.
ASJC Scopus subject areas