Synthetic apolipoprotein A-I mimetic peptide 4F (4F) decreases macrophage infiltration in renal tissues after myocardial infarction (MI) and after radiocontrast (RC) administration. Immunostaining for CD68 in all groups: Sham (sham-operated rats); MI (rats induced to MI by ligation of left coronary artery); MI+RC (rats induced to MI and receiving, 6 h later, femoral vein injection of iopamidol); MI+4F (rats induced to MI and receiving, 6 h later, intraperitoneal injection of 4F); and MI+RC+4F (rats induced to MI and receiving, 6 h later, femoral vein injection of iopamidol and intraperitoneal injection of 4F). Note the marked accumulation of CD68 macrophages in kidneys of MI and MI+RC groups compared with Sham, MI+4F, and MI+RC+4F groups. Quantitative analysis of CD68-positive cells is shown (n = 8/group, ANOVA).