The Research On The Thresholds Of Lactate And The Expressions Of MCTs In Rat Cardiac Myocytes And Fibroblasts

Aims:To observe the activity of cardic myocytes and fibroblasts and figure out the cells survival rate by building lactate incubation model. In order to research the thresholds of lactate in rat cardiac myocytes and fibroblasts. Extracte cell protein and analyse by using Western immunoblotting to observe the expressions of the MCTs (monocarboxylate transporters) in rat cardiac myocytes and fibroblasts. In order to lay a foundation for a further research on the lactate shuttle between cardiac myocytes and fibroblasts.Methods:Neonatal rat cardic myocytes and fibroblasts were cultured in vitro, and added the lactate of different concentrations (0mmol/L, 1mmol/L, 2mmol/L, 4mmol/L, 8mmol/L, 16mmol/L, 32mmol/L), which had the same PH. Observe the activity of cardic myocytes and fibroblasts by determining OD value, and figure out the cells survival rate. The protein of the cardic myocyte and fibroblasts were extracted and analysed by using Western immunoblotting. Observe the expression of MCT1 and MCT4 in different cells.Results:(1)When the concentrations of the lactate were 2mmol/L and 4mmol/L, the OD value and the cell survival of the cardic myocytes were highest. Compared with other groups, the results of two groups were statistically significant difference. But the results between two groups were not statistically significant. (2)When the concentrations of the lactate were 4mmol/L and 8mmol/L, the OD value and the cell survival of the fibroblasts were highest. Compared with other groups, the results of two groups were statistically significant difference. But the results between two groups were not statistically significant. (3)The expression of MCT1 is higher than MCT4 in both two cells. And the expression of MCT1 and MCT4 in cardic myocytes is higher than the fibroblasts.Discussion:When the lactate concentrations are 2mmol/L and 4mmol/L, the the activity and the cells survival rate of cardic myocytes are highest. Because the catdic myocytes import the plenty of lactate and energy supply are abundant. So the cells survival rates are highest. From this we deduce the threshold of cardic myocytes is 2-4mmol/L. But with the lactate concentration rising, the activity of cardic myocyres is low. Because the cells stop importing lactate, and convert to export lactate. And the energy supply reduces. So the cells survival rates reduce. When the lactate concentrations are 2mmol/L and 4mmol/L, the the activity and the cells survival rate of fibroblasts are highest. From this we deduce the threshold of fibroblasts is 4-8mmol/L. But the threshold of fibroblasts is 4-8mmol/L.Both MCT1 and MCT4 express in cardic myocytes and fibroblasts. It demonstrates that two cells have the required transport for lactate shuttle, they can import and export lactate easily. And the expression of MCT1 which is responsible for importing lactate is high. In contrast, the expression of MCT4 which is responsible for exporting lactate is low. It demonstrates that cardic myocytes and fibroblasts both mainly import and oxidize lactate. Meanwhile, the result that the expressions of MCT1 and MCT4 in cardic myocytes are higher than in fibroblasts indicates the metabolism of lactate in the cardic myocytes is more active.Conclusions:The results that the threshold of cardic myocytes and fibroblasts are different indicate that the metabolism way of lactate in cardic myocytes and fibroblast are different. And it may be the biochemical basis of the cell-to-cell lactate shuttle between two cells. And the expressions of MCTs in cardic myocytes and fibroblasts present different species and abundances. It may be the structure basis of the cell-to-cell lactate shuttle between two cells.