Physiopathology of splanchnic vasodilation in portal hypertension

Figure 3 Vasodilation/contractile signaling in vascular smooth muscle cells. The contractile state of vascular smooth muscle depends on the phosphorilation state of myosin light chains (MLCs). Under normal conditions, contractile agonists activate G protein couple receptors (GPCR). These receptors subsequently activate downstream effectors such as phospholipase C (PLC) and GTPase RhoA, leading to the increase of MLC phosphorilation via the activation of MLC kinase or the inhibition of MLC phosphatase. DAG: diacylglycerol; IP3: inositol triphosphate; PIP₂: Phosphatidylinositol 4,5-bisphosphate; PKC: protein kinase C.