Thimerosal modulates the agonist-specific cytosolic Ca2+ oscillatory patterns in single pancreatic acinar cells of...

Modulation of the agonist-specific cytosolic Ca2+ oscillatory pattern by thimerosal has been investigated in single pancreatic acinar cells using patch-clamp perforated whole-cell recording to measure the calcium-dependent chloride current (I(C1)(Ca2+)). 1 microM thimerosal, which fails to evoke Ca2+ oscillation alone, clearly changed the pattern of Ca2+ oscillation from pulsatile spikes (evoked by low concentrations of activators) to sinusoidal or transient oscillations. The mimetic action of thimerosal was independent of extracellular Ca2+, was blocked by extracellular application of dithiothreitol or 10 mM caffeine, as well as by internal perfusion with heparin; but was unaffected by ruthenium red. We conclude that thimerosal modulates the agonist-specific cytosolic Ca2+ oscillatory patterns mediated by sensitizing the InsP3-induced Ca2+ release.