In an attempt to evaluate the effect of St. Thomas' hospital cardioplegic solution(STH) I and II on the cultured rat myocardial cells, beating rate, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(tetrazolium MTT) and lactate
dehydrogenase
activity were investigated, and also light and electron microscopic studies were carried out.
After rat myocardial cells were cultured for 72 hours, cells were treated with STH I or with STH II solution for 30 and 120min and thereafter myocardial cells were cultured in control medium for 24 hours.
@ES The results obtained were as follows:
@EN 1. Beating rate was 154 times per min. in control group, 147 times per min. in STH I solution(for120 min.)-treated group and 145 times in STH II solution(for 120min.)-treated group.
2. MTT absorbances by MTT assay were 102% in STH I solution(for 120 min.)-treated group and 93% in STH II solution(for 120min.)-treated group compared group compared with control group.
3. The amount of lactate dehydrogenase released into the medium were 123% in STH I solution(for 120 min.)-treated group and 109% in STH II solution(for 120 min.)-treated group compared with control group.
4. In the light microscopy examination, myocardial cells showed no differences between experimental and control groups in their number and shape.
5. In the electron microscopy examination, myocardial cells treated with STH I solution showed fewer destroyed mitochondria compared to STH II solution-treated group.
These results suggest that both St. Thomas' cardioplegic solution STH I and STH II have no cytotoxicity on cultured rat myocardial cells, but STH II solution has more protective effect on myocardial cells compared to STH I solution.
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