Figure 1. AHR activation is present in CKD skeletal muscle and associates with mitochondrial respiratory function.

(A) Graphical depiction of tryptophan metabolism and the AHR signaling pathway. (B) qPCR quantification of AHR, CYP1A1, and CYP1B1 mRNA signaling in gastrocnemius muscle biopsies from patients without (n = 5) and with CKD (n = 8–10). (C) Relationship between muscle mitochondrial oxygen consumption (JO₂) and CYP1A1 in patients with and without CKD. (D) Immunoblotting of the AHR protein in skeletal muscle of mice. (E) qPCR quantification of Cyp1a1 mRNA levels in C₂C₁₂ myotubes treated with tryptophan-derived uremic metabolites indoxyl sulfate (IS), indole-3-acetic acid (IAA), L-kynurenine (L-Kyn), and kynurenic acid (KA) (n = 3–4 biological replicates/group). Statistical analyses performed using 2-tailed Student’s t test. Data are shown as mean ± SD. *P < 0.05, **P < 0.01, and ****P < 0.0001.