Effect of Homocysteine on Ischemia-Reperfusion Injury in Isolated Rat Heart

BACKGROUND:
Homocysteine is a sulfur containing amino acid, and its high concentration is known as cardiovascular risk factor results in oxidative stress and vascular disease. There are some studies on cardiovascular effects of homocysteine but its effect on the reperfusion injury is not completely understood. Hence the effect of homocysteine on the ischemia–reperfusion injury in isolated rat heart has been considered in this study

METHODS:
In this experiment 32 male wistar rats were used. The hearts of animals were isolated according to Langendorff method and perfused by Kreb’s solution under constant pressure. Experimental protocol in control group was I: Stabilization period and recording of baseline values, II: Normothermic global ischemia (40min), and III: Reperfusion (45 min). In addition to this protocol, homocysteine (0.5 mmol/lit) was added to Kreb’s solution for 30 min before and 5 min after ischemia in test group I. In test group II and III, homocysteine (0.1 & 0.05 mmol/lit) were added to solution for 60 min before and 5 min after ischemia, respectively. Functional cardiac parameters were measured during different periods. Data were analyzed by paired t-test, unpaired t-test and one way ANOVA followed by Tukey post test appropriately

FINDINGS:
The maximum concentration of homocysteine (0.5 mmol/lit) significantly increased coronary flow before ischemia. In addition, rate pressure product (heart rate×left ventricular pressure) as a functional cardiac parameter in test group II (5955±566 beat per minute×mmHg) significantly decreased in comparison to control group (10818±765) after 45 min reperfusion (P<0.05).

CONCLUSION:
The findings of this study showed the exaggerated reperfusion injury in the test group with longer perfusion time and moderate concentration of homocysteine; This effect is suggested to be due to exaggerated oxidative stress in reperfusion period.

KEY WORDS:
Homocysteine, Isolated heart, Ischemia-reperfusion injury