Effects of ethyl pyruvate on cardiac function recovery and apoptosis reduction after global cold ischemia and reperfusion

Abstract

The present study used an in vitro model of cold cardioplegia in isolated working rat hearts to evaluate the possible role of ethyl pyruvate (EP) in promoting cardiac function and preventing apoptosis. Two groups of rats were evaluated; the EP (2 mM EP; n=8) and control (n=8) groups. Isolated rat hearts were perfused with Krebs-Henseleit buffer (KHB) for 30 min, arrested with cardioplegic solution and stored for 4 h in B21 solution at 4°C. The hearts were reperfused with KHB for 45 min. EP was added to the cardioplegic and storage solutions and also to KHB for reperfusion. Cardiac parameters of the heart rate, including left ventricular systolic pressure, left ventricular end-diastolic pressure, left ventricular developed pressure and maximal rise rate of the left ventricular pressure, were monitored. In addition, coronary flow, adenosine triphosphate (ATP) levels and malondialdehyde (MDA) content were recorded and apoptotic cell determination was detected. The functional parameters in the EP group were significantly higher compared with those in the control group during the reperfusion period (P<0.05). In addition, ATP levels were higher in the EP group than in the control group and the content of MDA was lower in the EP group than in the control group. A concentration of 2 mM EP significantly reduced the number of apoptotic cells in the EP group compared with that of the control group (P<0.05). Therefore, EP significantly preserved cardiac function, enhanced tissue ATP levels, attenuated myocardial oxidative injury and markedly reduced apoptosis following myocardial ischemia in an in vitro model of 4 h of cold cardioplegia and reperfusion.

Keywords: apoptosis; ethyl pyruvate; heart; rat; transplantation.

Figure 1

Effect of pre- and post-ischemic treatment with EP on the rate of recovery of LVDP during the reperfusion period after 4 h of global cold ischemia in isolated rat hearts. EP treatment during the reperfusion period significantly improved LVDP. Values are expressed as the mean ± standard error of the mean (n=8 per group). ^*P<0.05, vs. respective pre-ischemia value; ^#P<0.05, vs. control group. LVDP, left ventricular developed pressure; EP, ethyl pyruvate.

Figure 2

Effects of pre- and post-ischemic treatment with EP on the rate of recovery of +LVdp/dt_max during the reperfusion period after 4 h of global cold ischemia in isolated rat hearts. EP treatment during the reperfusion period significantly improved +LVdp/dt_max. Values are expressed as the mean ± standard error of the mean (n=8 per group). ^*P<0.05, vs. respective pre-ischemia value; ^#P<0.05, vs. control group. +LVdp/dt_max, maximal differentials of LVDP; LVDP, left ventricular developed pressure; EP, ethyl pyruvate.

Figure 3

Effects of pre- and post-ischemic treatment of EP on ATP levels and MDA content during the reperfusion period after 4 h of global cold ischemia in isolated rat hearts. The levels of ATP were higher in the EP group than in the control group. The content of MDA was lower in the EP group compared with the control group. Values are expressed as the mean ± standard error of the mean (n=8 per group). ^*P<0.05, vs. corresponding value of the control group. EP, ethyl pyruvate; MDA, malondialdehyde; ATP, adenosine triphosphate.

Figure 4

Percentage of nuclei staining positive for the TUNEL assay in heart tissue samples after 4 h of global cold ischemia and 45 min of reperfusion in the EP (3.1±1.2%) and control (6.8±1.6%) groups. EP, ethyl pyruvate; TUNEL, terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling.