Therapeutic effects of 1,25-dihydroxyvitamin D and losartan co-administration on myocardial ischemia-reperfusion injury in rats

Studies support the idea that low levels of vitamin D are associated with a higher risk of heart disease. Losartan has also been prescribed as a drug commonly used for treating hypertension. The aim of the current study was to investigate the effects of 1,25-dihydroxyvitamin D in combination with a non-hypotensive dose of losartan on myocardial infarct size, reperfusion-induced arrhythmia and cardiac expression of survival factors in the ischemicreperfused rat heart. Male rats were randomly divided into untreated ischemia-reperfused rats (IR group) and groups pretreated with losartan (Los+IR) or vitamin D3 (VitD+IR) or both of them (Los+VitD+IR). Animals were subjected to 30 min of left coronary artery occlusion followed by 120 min of reperfusion. Infarct size measurement was performed using tetrazolium chloride. Incidence of arrhythmia was analysed according to Lambeth convention. Gene expression was evaluated by real time RT-PCR technique. In VitD+IR and Los+IR groups the infarct size did not differ significantly. In Los+VitD+IR group, the infarct size was decreased by 21.4±7.3% (P<0.001 vs. IR, P<0.05 vs. VitD+IR, P<0.01 vs. Los+IR). The number of ventricular ectopic beats was 201±32 beats in Los+VitD+IR group (P<0.001 vs. IR, P<0.01 vs. VitD+IR, P<0.05 vs Los+IR). The increase of thioredoxin-1 and catalase transcription levels was not significant in Los+IR and VitD+IR groups, however, in Los+VitD+IR group the mRNA levels of these survival factors were markedly increased (P<0.001 vs IR). Co-administration of a non-hypotensive dose of losartan and vitamin D3 protects the heart against ischemia-reperfusion injury accompanied by an increase in transcription of prosurvival factors.