Cardiac output and cardiac GATA-4 phosphorylation and troponin I expression in the heart. Comparison of streptozotocin-induced diabetic rats (STZ) and normal (Wistar) rats. Each column shows the mean ± SEM (n = 6). ***P < 0.001 (A). STZ diabetic rats were treated with insulin or phlorizin at a dose sufficient to correct the blood sugar level for 4 days. Then, rats were sacrificed and nuclear GATA-4 phosphorylation (B) and troponin I expression (C) were detected by Western blot analysis. The results are presented as the mean ± SEM (n = 6 per group). *P < 0.05 and **P < 0.01 as compared with the STZ rats.