Abstract
BackgroundInsulin-induced hypoglycemia has been demonstrated to prolong the corrected QT (QTc) interval. Prolongation of the QTc interval, especially in diabetic patients using insulin, can cause fatal ventricular arrhythmias. The aim of this study was to evaluate the effects of metoprolol, diltiazem, and pilocarpine on hypoglycemia-induced QTc prolongation.MethodsThirty male rats were randomly distributed into the following five groups: Group 1 (1 mL/kg saline, n=6), Group 2 (40 U/kg crystalline insulin + saline, n=6), Group 3 (40 U/kg crystalline insulin + 1 mg/kg metoprolol, n=6), Group 4 (40 U/kg crystalline insulin + 0.8 mg/kg pilocarpine, n=6), and Group 5 (40 U/kg crystalline insulin + 2 mg/kg diltiazem, n=6). Three hours after insulin injection, the blood glucose level was measured in all groups. Blood glucose <40 mg/dl was defined as hypoglycemia. Electrocardiograms (ECG) were taken in lead I (DI), and QTc was calculated by using Bazett’s formula.ResultsGroup 2 (insulin + saline) showed that it had a significantly prolonged QTc interval as compared to the control group (p<0.0001). However, treatments of the rats with metoprolol, pilocarpine, and diltiazem significantly prevented prolongation of the QTc interval as compared to the insulin + saline group (p<0.005, p<0.005, and p<0.01, respectively).ConclusionThe findings of the present study demonstrated the efficacy of metoprolol, pilocarpine, and diltiazem in the prevention of hypoglycemia-induced QTc prolongation in male rats.
Highlights
Hypoglycemia may play a critical role in the sudden death of young people with diabetes mellitus
The findings of the present study demonstrated the efficacy of metoprolol, pilocarpine, and diltiazem in the prevention of hypoglycemia-induced QTc prolongation in male rats
We aimed to investigate whether these agents have beneficial effects on the hypoglycemia-induced prolongation of QTc interval in an experimental rat model
Summary
Hypoglycemia may play a critical role in the sudden death of young people with diabetes mellitus. Several clinical and experimental studies have confirmed the pro-arrhythmic effects of hypoglycemia in type 1 and type 2 diabetes patients [1,2]. Hypoglycemia may delay ventricular repolarization, prolong the corrected QT (QTc) interval, and stimulate severe ventricular cardiac arrhythmias, predisposing the patient to sudden arrhythmic death [3]. Metoprolol is a member of selective beta-blockers and class II anti-arrhythmic agents [11,12,13]. Metoprolol decreases the heart rate and is effective for the treatment of supraventricular tachycardia and ventricular tachycardia. Insulin-induced hypoglycemia has been demonstrated to prolong the corrected QT (QTc) interval. Prolongation of the QTc interval, especially in diabetic patients using insulin, can cause fatal ventricular arrhythmias. The aim of this study was to evaluate the effects of metoprolol, diltiazem, and pilocarpine on hypoglycemia-induced QTc prolongation
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