The cytoskeleton serves as a signal modulator for Ca 2+ and cAMP-regulated cell functions including the secretion of ions and granule contents. The interaction between Ca 2+ and cAMP signaling systems potentiates amylase secretion and suppresses Cl − secretion in the parotid glands. In this study, we investigated the role of the cytoskeleton in the modulation of Cl − and amylase secretion from rat parotid acinar cells upon activation of each intracellular signaling system and their interaction. Cytochalasin D markedly inhibited the Ca 2+ -activated outwardly rectifying Cl − current at positive membrane potentials and carbachol (CCh)-induced Cl − currents in the whole-cell configuration at −80 mV, whereas colchicine enhanced Cl − currents. Cytochalasin D, but not colchicine, markedly inhibited CCh-induced Cl − secretion. Synergistic actions of CCh and forskolin on Cl − and amylase secretion were observed even in the presence of cytochalasin D. These results suggest that the synergistic effects of Ca 2+ and cAMP signaling systems on amylase and Cl − secretion do not require actin filament integrity but that secretion by the two signals themselves does require actin filament integrity.Actin and tubulin cytoskeletons are involved in the regulation of cell morphology and intracellular transport. They also affect the membrane permeability and secretory functions of glandular cells; cytoskeletal integrity modulates amylase secretion by β-adrenergic agonists (4,5,24,37) and cytoskeletal organization is related to the regulation of ion channels (1, 12), exchangers (16) and transporters (7) involved in the secretion of salivary fluid during cholinergic stimulation (22,27). Cytoskeletal integrity might regulate Cl −

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