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Updated: Apr 14, 2026
In vitro Assessment of Cardiac Reprogramming by Measuring Cardiac Specific Calcium Flux with a GCaMP3 Reporter
Published on: February 22, 2022
[Combined transgenic inhibition of CaMKII and Ik1 on cardiac remodeling]
Yun Huang1, Miao Dai1, Yi-Mei Du2
1Department of Gerontology, Union Hospital, Huazhong University of Science and Technology, Wuhan 430022, China.
Abstract:
This study was aimed to establish an experimental mouse model of combined transgenic inhibition of both multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and inward rectifier potassium current (Ik1), and to observe whether the specific inhibition of both CaMKII and Ik1 can bring about any effects on cardiac remodeling. Mice were divided into 4 groups: wild type (WT), CaMKII inhibited (AC3-I), Ik1 inhibited (Kir2.1-AAA) and combined inhibition of both CaMKII and Ik1 (AC3-I+Kir2.1-AAA). Mice in each group received electrocardiogram (ECG) and echocardiography examination. ECG in the condition of isoproterenol (ISO) injection was also checked. The whole cell patch clamp technique was used to measure Ik1 and the transient outward potassium current (Ito) from enzymatically isolated myocytes of left ventricle. In the condition of basal status, no significant changes of heart rate, PR interval and QRS interval were observed. No mouse showed ventricular arrhythmias in all of the 4 groups. After ISO injection, each group presented no significant ventricular arrhythmias either. The indexes measured by M-mode (motion-mode) and two-dimensional echocardiography had no significant differences among the four groups. Ik1 in AC3-I group was significantly higher than those in other three groups (P < 0.01) because of the results brought about by CaMKII inhibition. Among the latter three groups, both Kir2.1-AAA group and AC3-I+Kir2.1-AAA group had a significant reduced Ik1 compared with that of WT group, which was due to the Ik1 inhibition (P < 0.01). Ito in AC3-I group was higher than that of the other three groups (P < 0.01), but there were no significant differences in Ito among WT, Kir2.1-AAA and AC3-I+Kir2.1-AAA groups. Thus, combined transgenic myocardial CaMKII and Ik1 inhibition eliminated the up-regulation of Ik1 in CaMKII inhibited mice, and had no effects on cardiac remodeling including heart structure and function as well as arrhythmias at the basic and ISO conditions. The results of this study may provide a basis for the further investigation of combined inhibition of CaMKII and Ik1 in pathogenic cardiac remodeling.
Insights
Combined inhibition of CaMKII and Ik1 in mice prevented increased Ik1 levels without affecting cardiac remodeling or arrhythmias. This research offers a foundation for studying combined inhibition in heart disease.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Pharmacology
Background:
- Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and inward rectifier potassium current (Ik1) play roles in cardiac function.
- Understanding their combined effects is crucial for cardiac remodeling research.
Purpose of the Study:
- To create a mouse model inhibiting both CaMKII and Ik1.
- To assess the impact of combined inhibition on cardiac remodeling and arrhythmias.
Main Methods:
- Developed transgenic mouse models with inhibited CaMKII (AC3-I), Ik1 (Kir2.1-AAA), or both.
- Utilized electrocardiography (ECG), echocardiography, and patch-clamp techniques.
- Administered isoproterenol (ISO) to evaluate arrhythmia susceptibility.
Main Results:
- Combined inhibition normalized elevated Ik1 levels seen with CaMKII inhibition alone.
- No significant differences in cardiac structure, function, or arrhythmias were observed across groups.
- CaMKII inhibition increased Ik1 and transient outward potassium current (Ito); Ik1 inhibition reduced Ik1.
Conclusions:
- Combined transgenic inhibition of CaMKII and Ik1 effectively normalized Ik1 levels.
- This combined inhibition did not induce cardiac remodeling or arrhythmias under basal or stressed conditions.
- The findings support further investigation into combined CaMKII and Ik1 inhibition for pathogenic cardiac remodeling.
