Fig. 3
Left ventricular biochemistry in creatine transporter overexpressing mice (CrT-OE, n = 7) and in double transgenic animals (dTg, n = 6). Total creatine kinase (CK) activity was significantly elevated in dTg hearts (A), while there were no significant differences in total creatine levels (B), total adenine nucleotides (C), or in citrate synthase activity (D). In vivo 31P-CMRS found significantly higher PCr/ATP ratio in dTg hearts (E) and a linear relationship with total creatine levels (CrT-OE: y = 0.01018*x + 0.7489, r2 = 0.49; dTg: y = 0.02864*x + 0.1378, r2 = 0.66) with a significantly different intercept (P = 0.002), indicating that PCr/ATP levels are higher in dTg for any given value of total creatine (F). In contrast, there was no difference in PCr/ATP levels in the skeletal muscle adjacent to the heart (G). Data are mean ± SD with comparisons by unpaired Student’s t-test