Nitric oxide synthase in heart and thoracic aorta after liver ischemia and reperfusion injury: an experimental study in rats.

OBJECTIVES We tested the effects of liver reperfusion in the immunohistochemical expression of nitric oxide synthase on the thoracic aorta and the heart. MATERIALS AND METHODS We randomized 24 male Wistar rats into 3 groups: (1) control; (2) R2 group, with 60 minutes of partial (70%) liver ischemia and 2 hours of global liver reperfusion; (3) and R6 group, with 60 minutes of partial liver ischemia and 6 hours of global liver reperfusion. RESULTS In the heart, there was little, diffuse immunohistochemical endothelial staining; immunohistochemical inducible nitric oxide synthase staining was expressed in the adventitia layer of intramyocardial vessels in both cases, with a time-dependent but not statistically significant increase. In the thoracic aorta, a time-dependent decrease in endothelial nitric oxide synthase expression in the muscular layer after reperfusion, which was statistically significant in R6 versus the control. Positive immunostaining for inducible nitric oxide synthase was seen in the muscular and endothelial layers, and this varied from moderate in the control group, to light in the endothelium in groups R2 and R6. CONCLUSIONS We observed changes that may be implicated in heart injury and impairment of aortal tone after liver ischemia and reperfusion injury.