Collagen content, measured by hydroxyproline assay, in kidneys from mice treated with vehicle or Ang II. In CCR2+/+ with Ang II-induced hypertension, collagen content increased significantly (p < 0.025, vehicle vs Ang II), while in CCR2 −/−, this increase was not significant. Collagen content in Ang II-induced hypertension was significantly higher in CCR2+/+ compared to CCR2−/−; p < 0.025, CCR2+/+ vs CCR2−/−. (n = 6 per group).