P. Dobsak et al., Antioxidative properties of pyruvate and protection of the ischemic rat heart during cardioplegia, J CARDIO PH, 34(5), 1999, pp. 651-659
Citations number
36
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Formation of oxygen free radicals during heart transplantation seems to be
related to the alterations occurring during ischemia and reperfusion and co
uld explain the short preservation time of donor hearts. The aim of our stu
dy was (a) to analyze the protective effects of pyruvate during cold cardio
plegia and ischemia/reperfusion sequence, and (b) to investigate in vitro t
he radical scavenging properties of this compound. After 30 min of perfusio
n, isolated working rat hearts were arrested by cardioplegic solution, stor
ed 4 h in B21 solutions at 4 degrees C, and reperfused with Krebs-Henseleit
buffer for 45 min. Pyruvate (2 mM) was added to Krebs-Henseleit, cardiople
gic, and storage solutions, and functional parameters were recorded through
out the experiments. In a second part, control hearts and hearts treated wi
th pyruvate were cannulated via the aorta and perfused for 30 min by the La
ngendorff method, arrested by cardioplegic solution, stored 4 h in B21 solu
tions at 4 degrees C, and reperfused for 45 min by the Langendorff method.
Malonedialdehyde and alpha-tocopherol levels were determined on heart homog
enate. In situ detection of apoptotic cells also was performed on tissue sa
mples (left ventricle) at the end of the ischemia/reperfusion sequence. To
demonstrate in vitro the antioxidant effects of pyruvate, we monitored (a)
its hydroxyl radical scavenging properties by using electron para-magnetic
resonance (EPR) spectroscopy, and (b) the decrease of fluorescence of allop
hycocyanin, in the presence of a Fenton system (H2O2/Cu2+). Ischemia for 4
h, followed by myocardial reperfusion, resulted in substantially reduced me
chanical function. Hearts subjected to this ischemia and pretreated with py
ruvate showed a significant improvement in the function recovery. After the
ischemia/reperfusion protocol, no significant decrease of malonedialdehyde
levels was shown on hearts treated with pyruvate. However, alpha-tocophero
l levels were higher in the pyruvate group compared with the control group.
At the end of the reperfusion period, levels of apoptotic cells were signi
ficantly lower in hearts treated with pyruvate compared with control hearts
. EPR studies showed that pyruvate was an efficient hydroxyl scavenger, wit
h a median inhibitory concentration (IC50) of 8 mM. The allophycocyanin ass
ay also showed a dose-dependent effect of pyruvate against hydroxyl radical
s. In conclusion, these findings showed that pyruvate could prevent reperfu
sion injuries in the isolated heart, probably by its antioxidative properti
es. The application of pyruvate may contribute to the preservation of heart
s for organ transplantation.