Plasma fibronectin during myocardial ischemia-reperfusion: Effects of magnesium, diltiazem, and a novel Mac-1 inhibitor

The important role of fibronectin (Fn) has been recognized in patients with ischemic heart disease. However, serial changes of Fn during both brief and prolonged ischemia-reperfusion are poorly known. Plasma Fn was measured during acute myocardial infarction (AMI) and myocardial stunning (MS), and in the absence of myocardial injury. The effects of magnesium (Mg), diltiazem, and a Mac-1 inhibitor on the level of Fn were elucidated. Forty-nine swine underwent prolonged (50 min) or brief (8 min) coronary artery occlusion followed by reperfusion, while six control animals were free of ischemia. During the AMI experiments, plasma Fn underwent a significant progressive increase. Mg or diltiazem similarly affects the plasma Fn, reducing its release during the entire reperfusion period, and did not influence the plasma Fn in the absence of myocardial injury. Contrarily, Mac-1 inhibition resulted in the Fn elevation in controls, and during the occlusion phase, with no significant effect during reperfusion. There were no changes in the plasma Fn during MS, while inhibition of Mac-1 was associated with the significant increase of Fn during ischemia-reperfusion. Ability of Mg, diltiazem, and leumedins to modulate plasma Fn level may have direct clinical implications for the use of these agents in patients with coronary artery disease.