Cellular and molecular pharmacological studies on disturbance of CaィイD12+ィエD1 regulatory mechanisms in cardiomyocytes in diabetes

The present work was carried out in order to determine whether a decrease in cardiac Na D2 + CaD22 + CaD2 exchanger （NCX） activity observed in diabetes is caused by a reduction in NCX protein and mRNA Management els and to elucidate the significance of this decrease in alterations in [CaイD12+イD1]イD2 homeostasis in diabetic cardiomyocytes。NCX电流在肠道myocytes中被显著地减少了从链球菌素诱导的糖尿病大鼠心脏中被新的孤立化，而其电流密度被年龄匹配控制的55%左右。糖尿病在心血管蛋白和NCX 1 mRNA水平中发现了一个~ 30%的降解酶，一个NCX同位素表现在心脏的高水平。通过胰岛素治疗预防的降低NCX当前和NCX 1中的降解蛋白和mRNA水平的糖尿病。Although both diastolic and peak systolic [CaイイD22+イエD2]イイD2iイD2were not different between the two groups of myocytes， increasing external CaイD12+イエD1 concentration to high levels greatly elev ... More ated diastolic [CaイイD12+イエD1]イイD2iイエD2 in diabetic myocytes。Inhibition of NCX by reduction in extracellular NaイイD1+イエD1 by 50%could produce a marked rise in diastolic [CaイD12+イエD1]イイD2iイD2 in control myocytes in res\to high CaイD12+イエD1， as seen in diabetic myocytes。However， cyclopiazonic acid， an inhibitor of sarcoplasmic reticulum Ca D12+ Ca D1 pump ATPase， did not modify the high Ca D12+ Ca D1-induced changes in diastolic [Ca D12+ Ca D1]I in either control and diabetic myocytes。仅在来自糖尿病大鼠的纸张化妆品中，高Cai-D12 + Caused a marked rise in resting tension signifying a partial contracture that is possiblly due to an increase in diastolic [Cai-D12 + Cai-D1] Cai-D2 i Cai-D2.In conclusion， a diminished NCX function in diabetic myocyes show in this study result in the decreased level of cardiac NCX protein and mRNA. We suggest that this impaired NCX function may play an important role in alterations in CaイイD12+イイD1 handling when [CaイD12+イイD1]イD2iイD2 rises to pathological Management els。Less（低）

The present work was carried out in order to determine whether a decrease in cardiac NaィイD2+ィエD2-CaィイD22+ィエD2 exchanger (NCX) activity observed in diabetes is caused by a reduction in NCX protein and mRNA levels and to elucidate the significance of this decrease in alterations in [CaィイD12+ィエD1]ィイD2iィエD2 homeostasis in diabetic cardiomyocytes. The NCX current was significantly reduced in ventricular myocytes freshly isolated from streptozotocin-induced diabetic rat hearts, and its current density was about 55% of age-matched controls. Diabetes resulted in a 〜30% decrease in cardiac protein and mRNA levels of NCX1, a NCX isoform which is expressed at high levels in the heart. The reduced NCX current and the decreased protein and mRNA levels of NCX 1 in diabetes were prevented by insulin therapy. Although both diastolic and peak systolic [CaィイD22+ィエD2]ィイD2iィエD2 were not different between the two groups of myocytes, increasing external CaィイD12+ィエD1 concentration to high levels greatly elev … More ated diastolic [CaィイD12+ィエD1]ィイD2iィエD2 in diabetic myocytes. Inhibition of NCX by reduction in extracellular NaィイD1+ィエD1 by 50% could produce a marked rise in diastolic [CaィイD12+ィエD1]ィイD2iィエD2 in control myocytes in response to high CaィイD12+ィエD1, as seen in diabetic myocytes. However, cyclopiazonic acid, an inhibitor of sarcoplasmic reticulum CaィイD12+ィエD1 pump ATPase, did not modify the high CaィイD12+ィエD1-induced changes in diastolic [CaィイD12+ィエD1]I in either control and diabetic myocytes. Only in papillary muscles from diabetic rats, the addition of high CaィイD12+ィエD1 caused a marked rise in resting tension signifying a partial contracture that is possibly due to an increase in diastolic [CaィイD12+ィエD1]ィイD2iィエD2.In conclusion, a diminished NCX function in diabetic myocyes shown in this study results in part from the decreased levels of cardiac NCX protein and mRNA. We suggest that this impaired NCX function may play an important role in alterations in CaィイD12+ィエD1 handling when [CaィイD12+ィエD1]ィイD2iィエD2 rises to pathological levels. Less