Content of L-carnitine, meldonium and Methyl-GBB in heart (A) and blood plasma (C), after 14 days of treatment by meldonium (100 mg·kg−1) or Methyl-GBB (1, 5 and 20 mg·kg−1). Content of L-carnitine and Methyl-GBB in heart tissue (B) and blood plasma (D,) after 3, 7 and 14 days of treatment by Methyl-GBB at a dose of 5 mg·kg–1. Effect of Methyl-GBB (5 mg·kg−1) on the L-carnitine content in urine after single administration (E). Data shown are the means ± SEM of 5–10 animals. *P < 0.05, significantly different from control group; #P < 0.05, significantly different from meldonium group; Tukey's test.