[Calcium sensitivity in vascular smooth muscle cell during hypoxic pulmonary vasoconstriction].

Hypoxic pulmonary vasoconstriction is a means of optimising the oxygenation of blood in the lungs by redistributing the flow from poorly ventilated areas into well ventilated ones. It is caused by a direct effect of hypoxia on pulmonary vascular smooth muscle cells. For a vascular smooth muscle cell to contract, an increased intracellular concentration of calcium is needed. However, the contraction force can also be regulated independently of calcium concentration by calcium sensitivity. The sensitivity is regulated mainly by activation/deactivation of myosin light chain phosphatase. Several metabolic pathways converge on this enzyme. The increase in calcium sensitivity is an important process during hypoxic pulmonary vasoconstriction.