AI Article Synopsis
- - The study investigates how low potassium levels (hypokalemia) affect the electrical behavior of the heart's left ventricle in rabbits, particularly focusing on ventricular repolarization and the potential risk for dangerous heart rhythms (malignant ventricular arrhythmia).
- - Twenty rabbits were divided into control (normal potassium) and hypokalemic groups to test differences in electrical properties like action potential duration and ventricular fibrillation threshold, revealing significant alterations in the hypokalemic group.
- - Results showed that hypokalemia prolonged repolarization duration and reduced the voltage required to induce fibrillation, indicating an increased risk for serious heart arrhythmias, especially associated with changes in specific protein expression related to heart muscle function.
Article Abstract
Objective: To observe effects of hypokalemia on transmural heterogeneity of ventricular repolarization in left ventricular myocardium of rabbit, and explore the role of hypokalemia in malignant ventricular arrhythmia (MVA).
Methods: A total of 20 rabbits were randomly divided into control group and hypokalemic group. Isolated hearts in the control group were simply perfused with modified Tyrode's solution, and were perfused with hypokalemic Tyrode's solution in hypokalemic group. Ventricular fibrillation threshold (VFT), 90% monophasic action potential repolarization duration (APD90) of subepicardial, midmyocardial and subendocardial myocardium, transmural dispersion of repolarization (TDR) and C×43 protein expression in three layers of myocardium were measured in both groups.
Results: VFT in the control group and the hypokalemic group were (13.40 ± 2.95) V, and (7.00 ± 1.49) V, respectively. There was a significant difference between two groups (P<0.01). APD90 of three myocardial layers in the hypokalemic group were significantly prolonged than those in the control group (P<0.01). ΔAPD90 in the hypokalemic group and the control group were (38.10 ± 10.29) ms and (23.70 ± 5.68) ms, and TDR were (52.90 ± 14.55) ms and (36.10 ± 12.44) ms, respectively. ΔAPD90 and TDR in the hypokalemic group were significantly higher than those in the control group (P<0.05), and the increase in APD90 of midmyocardium was more significant in the hypokalemic group. Cx43 protein expression of all three myocardial layers were decreased significantly in the hypokalemic group (P<0.01), and ΔCx43 was significantly increased (P<0.05). Reduction of Cx43 protein expression was more significant in the midmyocardium.
Conclusions: Hypokalemic can increase transmural heterogeneity of C×43 expression and repolarization in left ventricular myocardium of rabbit, and decrease VFT and can induce MVA more easily.
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| http://dx.doi.org/10.1016/S1995-7645(13)60079-6 | DOI Listing |
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