OXIDIZED LOW-DENSITY LIPOPROTEINS AND MICROVASCULAR RESPONSES TO ISCHEMIA-REPERFUSION

The objective of this study was to determine whether ischemia and repe rfusion (I/R) and/or chronic arterial hypertension potentiates the leu kocyte-endothelial cell adhesion (LECA) and microvascular dysfunction elicited by oxidized low-density lipoproteins (ox-LDL). Mast cell degr anulation, leukocyte adherence adn emigration, and albumin leakage wer e monitored in postcapillary venules of rat mesentery. Intra-arterial infusion of copper-oxidized LDL (Cu-LDL), at a concentration that does not directly affect the microvasculature, significantly enhanced the I/R-induced recruitment of adherent and emigrated leukocytes but does not affect the increased albumin leakage and mast cell degranulation r esponses normally observed after I/R. Infusion of a higher concentrati on of Cu-LDL in nonischemic mesentery of either normotensive Wistar-Ky oto or spontaneously hypertensive rats elicited significant yet simila r increases in LECA, mast cell degranulation, and albumin leakage. The se findings indicate that 1) ox-LDL act synergistically with I/R to pr omote leukocyte recruitment in postcapillary venules but without an ac companying exacerbation of albumin leakage, and 2) ox-LDL do not elici t a more intense inflammatory response in the microvasculature of hype rtensive versus normotensive animals.