Change Of Calcium Channels And Intracellular Free Calcium In Interstitial Cells Of Cajal From Diabetic Gastroparesis Rats

Abnormity of gastrointestinal (GI) tract motor is frequently encountered in patients with diabetes, it occurs in up to 30–50% of patients of type 1 or type 2 diabetes, namely Diabetic Gastroparesis(DGP). However, the pathophysiology of diabetic gastroparesis is still not delineated. A great number of studies show that abnormalities of gastric myoelectric activity were recorded in diabetic gastroparesis. Interstitial cells of cajal serve as pacemaker cells and generate and propagate electrical slow wave which has effects on the frequency, velocity of propagation of gastrointestine. The spontaneity activity of ICC comes under many biologic substances, such as the condition of ion, hormone and so on. Many ions have correlation with it, especially calcium.Objective:To study the change of calcium channels and Intracellular free Calcium in interstitial cells of Cajal from diabetic gastroparesis rats.Methods: SD rats were randomly divided into diabetic group and control group. The diabetic model of rats were duplicated with STZ once intraperitoneally. After establishing diabetic rat model for 8 weeks , interstitial cells of Cajal were isolated and identified with the c-Kit antibody. Then, inward calcium channels current were recorded by using whole-cell patch clamp technique; Intracellular free Calcium in interstitial cells of Cajal were observed by electrictelescopy.Results:The I-V curve of diabetic gastroparesis group upward compared with the normal group. each current value is less than normal under its test voltage. The most activation voltage of normal groups is 0 mV compared with diabetic gastroparesis group which is -10mV.The reversal potential decreased from 35mV to 22mV. The steady-state activation curves of Ica shifted rightward; 2. FI of [Ca²⁺]i in diabetic gastroparesis rats increased.Conclusion: 1.The results showed the decrease of the calcium inward current in diabetic gastroparesis rat and the steady-state activation curves of Ica shifted rightward. current-voltage curve of Ica shifted upward. 2. FI of [Ca²⁺]i in diabetic gastroparesis rats increased, forming calcium over-loading, and induced abnormal excitation rhythm of the cells. These findings probably indicated that changes of calcium in interstitial cells of Cajal maybe one of the mechanisms of gastroparesis in diabetic rats.