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Published on: September 18, 2017
Decrease in calcium-sensing receptor in the progress of diabetic cardiomyopathy
Shu-zhi Bai1, Jian Sun, Hao Wu
1Department of Pathophysiology, Harbin Medical University, Harbin 150086, China.
Abstract:
To observe the dynamic expression of calcium-sensing receptor (CaSR) in myocardium of diabetic rats and explore its role in diabetic cardiomyopathy (DCM), 40 male Wistar rats were randomly divided into 4 groups including control, diabetic-4 weeks, diabetic-8 weeks and spermine treatment groups (240 μM of spermine in drinking water). The type 2 Diabetes mellitus (DM) models were established by intraperitoneal injection of streptozotocin (STZ, 30 mg/kg) after high-fat and high-sugar diet for one month. The echocardiographic parameters were measured, cardiac morphology was observed by electron microscope and HE staining. The intracellular calcium concentration ([Ca(2+)](i)) was detected by laser-scanning confocal microscope. Western blot analyzed the expression of CaSR, protein kinase C α(PKC-α) and calcium handling regulators, such as phospholamban (PLN), Ca(2+)-ATPase (SERCA), and ryanodine receptor (RyR). Compared with control group, [Ca(2+)](i) and the expression of CaSR, RyR and SERCA/PLN were decreased, while PKC-α and PLN were significantly increased in a time-dependent manner in diabetic groups. Meanwhile diabetic rats displayed abnormal cardiac structure and systolic and diastolic dysfunction, and spermine (CaSR agonist) could prevent or slow its progression. These results indicate that the CaSR expression of myocardium is reduced in the progress of DCM, and its potential mechanism is related to the impaired intracellular calcium homeostasis.
Insights
Diabetic cardiomyopathy (DCM) involves reduced myocardial calcium-sensing receptor (CaSR) expression, impairing calcium handling. Spermine, a CaSR agonist, may prevent DCM progression by restoring calcium homeostasis.
Area of Science:
- Cardiology
- Endocrinology
- Molecular Biology
Background:
- Diabetic cardiomyopathy (DCM) is a cardiac complication of diabetes mellitus (DM).
- The role of the calcium-sensing receptor (CaSR) in DCM pathogenesis is not fully understood.
- Intracellular calcium ([Ca(2+)](i)) dysregulation is a hallmark of cardiac dysfunction.
Purpose of the Study:
- To investigate the dynamic expression of CaSR in the myocardium of diabetic rats.
- To explore the role of CaSR in the development and progression of DCM.
- To examine the effect of spermine, a CaSR agonist, on cardiac function in diabetic rats.
Main Methods:
- Type 2 DM model induced by streptozotocin (STZ) in Wistar rats.
- Echocardiography for cardiac function assessment.
- Western blot for protein expression analysis (CaSR, PKC-α, PLN, SERCA, RyR).
- Measurement of intracellular calcium concentration ([Ca(2+)](i)).
Main Results:
- Diabetic rats showed decreased myocardial CaSR, RyR, and SERCA/PLN expression over time.
- Increased intracellular calcium ([Ca(2+)](i)), PKC-α, and PLN levels were observed in diabetic rats.
- Cardiac structure and function (systolic and diastolic) were impaired in diabetic rats.
- Spermine treatment attenuated cardiac dysfunction and structural abnormalities.
Conclusions:
- Myocardial CaSR expression is reduced during DCM progression.
- Impaired intracellular calcium homeostasis is a key mechanism in DCM.
- CaSR modulation may represent a therapeutic target for diabetic cardiomyopathy.
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