Excess heme leads to cardiomyopathy in mouse model of sickle cell disease through Hmox1 upregulation. (A-E,H) Sickling (HbSS) mice and nonsickling (HbAS) littermates (males and females, 16-24 weeks old) fed facility chow were euthanized to collect tissues. (A) Serum heme and (B) hemopexin (Hx) levels were determined by colorimetric analysis and ELISA, respectively. (C) Serum heme was normalized to hemopexin to determine relative amounts of Hx-free heme. (D) Relative mRNA expression was determined using qPCR in cardiac tissue and normalized to β-actin. (E) Serum creatine kinase-MB (CK-MB) levels were measured by ELISA. (F-G, I) HbAS and HbSS mice were injected with human Hx (4 mg/kg) once a week for 4 weeks. (F) Serum heme levels were determined by colorimetric analysis. (G) Relative mRNA expression was determined using qPCR in cardiac tissue and normalized to β-actin. (H-I) Relative protein expression of Hmox1 was determined using cardiac tissue and normalized to α-tubulin. Discontinuities between nonadjacent lanes of the same membrane were indicated by a solid line. (J-K) HbAS and HbSS mice were injected with hemin (25 mg/kg) or SnPP (12 mg/kg) intraperitoneally 3 times per week for 4 weeks, and cardiac Hmox1 expression was determined using western blot analysis. Discontinuities between nonadjacent lanes of the same membrane are indicated by a solid line. (K) Relative mRNA expression in cardiac tissue was determined by qPCR and normalized to β-actin. Results are representative of n = 7-11 per group. Data are expressed as mean ± standard error of the mean. Statistical significance was assessed using the (A-E, H) Student t test for 2-group comparison or (F-G, I-K) 1-way ANOVA followed by Tukey HSD post hoc test for comparison among 3 to 6 groups. *P < .05 vs HbAS mice of the same treatment. ^#P < .05 vs vehicle-treated mice of the same genotype.