Influence Of Different Concentration Glucose Culture Medium On Primary Neonatal Rat Myocardial Cells

The cultivation technology of primary neonatal rat myocardial cells, which was founded by Harary in1960, is very important and widely used in the study of myocardial physiology, cardiac hypertrophy, myocardial ischemia/reperfusion injury, myocardial regeneration and so on. Glucose, as one of the main components of neonatal rat myocardial cells culture medium, is essential for the growth and proliferation of the cardiomyocytes. The endoplasmic reticulum is responsible for the biosynthesis, transportation, modification and correct folding of intracellular proteins. The abnormal accumulation of unfolded or misfolded protein caused by certain factors can lead to endoplasmic reticulum stress (ERS). As has been proved, ERS is involved in many diseases, such as obesity, diabetes, cancer, cardiac hypertrophy, myocardial ischemia/reperfusion injury and so on. It is said that ERS may also be related to diabetic cardiomyopathy. GRP78(glucose regulated protein78) is considered as an important regulator to maintain the homeostasis of endoplasmic reticulum. which is also the classic marker for endoplasmic reticulum stress.We undertook our research to explore the influence of different concentration glucose medium on primary neonatal rat myocardial cells and whether high concentration glucose can induce ERS by observing the change of morphology, viability and GRP78expression level.Objective:To investigate the influence of different concentration glucose medium on primary neonatal rat myocardial cells and whether high concentration glucose can induce ERS.Methods:Neonatal rat myocardial cells were cultured in different concentration glucose mediums (5.6mmol/L (low),11.1mmol/L (medium) and25mmol/L (high)). The positive control was set as primary cultured neonatal rat myocardial cells incubated with tunicamycin (lmg/L or5mg/L for6h,12h or24h). Then morphology and throb status of the cells were observed under high optical phase contrast microscope, the viability was tested by CCK-8reduction assay and hematoxylin-eosin (HE) staining was applied to observe the configuration. Western blot and RT-PCR were applied to detect the expression level of GRP78.Results:Neonatal rat myocardial cells cultured in high and medium concentration glucose medium maintained more vigorous growth and proliferation, more pseudopodia. higher morphology scores, higher beating frequency and better viability compared to low concentration glucose medium group (p＜0.01). GRP78expression level was significantly higher in neonatal rat myocardial cells cultured in high concentration glucose medium than those cultured in medium and low concentration glucose medium (p＜0.01). The expression level of GRP78made no significant difference in neonatal rat myocardial cells incubated with tunicamycin (1mg/L or5mg/L) for6h,12h or24h.Conclusion:High concentration glucose induces significant endopalsmic reticulum stress in primary neonatal rat myocardial cells.