*4.1.1. At the arteriolar level*

The principal manifestation of I/R in arterioles is a loss of the vasodilatation-dependent en‐ dothelium and the appearance of spasms. [78] Widespread endothelial lesions decrease the production of nitric oxide and do not counterbalance the arterioles' tendency toward vaso‐ constriction. This tendency is highlighted in several tissues, such as skeletal muscle, heart, lung and brain. [79]-[82] The combined effects of IR and inflammation on arteriolar vasomo‐ tricity are well documented. The increase in the contractile response of the pulmonary and mesenteric microcirculation after cardiac surgery predisposes the patient to the develop‐ ment of pulmonary shunt or mesenteric ischemia, particularly during the administration of vasopressive drugs in the postextracorporeal circulation. [83 ],[84]
