Distribution of signaling molecules involved in vasopressin-induced Ca2+ mobilization in rat hepatocyte multiplets

In freshly isolated rat hepatocyte multiplets, Ca2+ signals in response to vasopressin are highly organized. In this study we used specific probes to visualize, by fluorescence and confocal microscopy, the main signaling molecules involved in vasopressin-mediated Ca2+ responses. Via receptors were detected with a novel fluorescent antagonist, Rhm(8)-PVA, The G alpha q/G alpha 11, PLC beta(3), PIP2, and InsP(3) receptors were detected with specific antibodies. Via vasopressin receptors and PIP2 were associated with the basolateral membrane and were not detected in the bile canalicular domain. G alpha q/G alpha 11, PLC beta(3), and InsP(3) receptors were associated with the basolateral membrane and also with other intracellular structures. We used double labeling, Western blotting, and drugs (cytochalasin D, colchicine) known to disorganize the cytoskeleton to demonstrate the partial co-localization of G alpha q/G alpha 11 with F-actin.