Age-dependent responses of the mesenteric vasculature to ischemia-reperfusion

The age-dependent responses of the mesenteric vasculature to ischemia-reperfusion (I/R) were compared in 2-mo-old and 2-yr-old rats. Measurements were made of leukocyte adherence, albumin leakage, and oxidative stress in postcapillary venules. In young rats I/R induced an increase in leukocyte adherence and albumin leakage, but in aged rats I/R induced an increase in albumin leakage without an increase in leukocyte adherence. Furthermore, I/R-induced oxidative stress was higher in the aged rats than in the young rats. To investigate whether the age-associated oxidative stress is related to a decrease in the role of nitric oxide, NG-nitro-L-arginine methyl ester (L-NAME) was superfused onto the mesentery of young and aged rats. L-NAME induced an increase in postcapillary protein leakage only in young rats; however, arteriolar constriction induced by L-NAME occurred in both age groups. These results suggest that different mechanisms contribute to the inflammatory responses and microvascular dysfunction elicited by I/R in young and aged rats.