3′:5′-cyclic guanosine monophosphate (cGMP) potentiates the inositol 1,4,5-trisphosphate-evoked Ca2+ release in guinea-pig hepatocytes

摘要: The effect of cGMP on noradrenaline-induced intracellular Ca2+ mobilization was investigated in whole-cell voltage-clamped guinea-pig hepatocytes. Treatment the cells with 8-Br-cGMP (1-500 microM) resulted an increase sensitivity to noradrenaline and inositol 1,4,5-trisphosphate (InsP3) photo-released from caged InsP3. positive release evoked by Ca(2+)-mobilizing agonists or InsP3 blocked a protein kinase G (PKG; cGMP-dependent kinase) inhibitor, RP-8-(4-chlorophenylthio)guanosine 3':5'-monophosphorothioate. affected neither basal concentration nor production In permeabilized hepatocytes, dose-response curve for InsP3-induced shifted left presence 8-Br-cGMP. Furthermore, treatment did not affect content InsP3-sensitive stores. These results indicate that potentiates response enhancing We suggest increases apparent affinity receptors hepatocytes probably phosphorylation via activation PKG.