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[Immunohistochemical study of Cx43 dephosphorylation in human left ventricular myocardium suffered by acute ischemia]
Shi-wei Zhang1, Shi-xin Liu, Li-bin Deng
1Department of Forensic Medicine, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, China. seaway_zhang@hotmail.com
Insights
In acute myocardial ischemia (AMI), connexin 43 (Cx43) undergoes dephosphorylation, indicating altered electrical coupling in the heart. This IHC detection of Cx43 dephosphorylation may aid in diagnosing early AMI, especially sudden cardiac death (SCD).
Area of Science:
- Cardiovascular Pathology
- Molecular Biology
- Biochemistry
Context:
- Sudden cardiac death (SCD) and acute myocardial ischemia (AMI) present diagnostic challenges, particularly in early stages.
- Connexin 43 (Cx43) is crucial for cardiac electrical coupling via gap junctions.
- Understanding Cx43 phosphorylation changes in AMI is vital for early pathological diagnosis.
Purpose:
- To detect the phosphorylation state of Cx43 in human left ventricular myocardium from sudden deaths due to AMI and control groups.
- To evaluate the significance of Cx43 phosphorylation changes in diagnosing early pathological changes of AMI.
- To assess myocardial mechanical coupling and membrane integrity in AMI.
Summary:
- Immunohistochemistry revealed dephosphorylated Cx43 in AMI myocardium, unlike controls where it was clearly localized at intercalated discs (IDs).
- Pan-Cadherin and myocardial membranes remained integrated at IDs across all groups, suggesting preserved mechanical coupling.
- Cx43 dephosphorylation was a distinct finding in AMI, contrasting with unchanged mechanical coupling.
Impact:
- Cx43 dephosphorylation serves as a potential biomarker for recognizing the onset of arrhythmia in AMI.
- This IHC-based detection method may aid in diagnosing AMI, especially SCD, even without apparent morphological changes.
- Findings highlight the role of altered electrical coupling in the pathophysiology of AMI.
Objective:
This study was performed to detect the phosphorylation state of Cx43 in human left ventricular myocardium among sudden deaths caused by acute myocardial ischemia (AMI) especially sudden coronary death (SCD) and control groups. And then evaluate the significance of these findings in diagnosing the early pathological changes of acute myocardial ischemia.
Methods:
Immunohistochemistry (IHC) SP techniques were adopted to detect the phosphorylation state of Cx43 in the left ventricular myocardium samples of 45 deceased, which classified as group I--SCD, group II & III (other two groups of AMI) and Group IV & V (two control groups, sudden death caused by lethal acute cranio-cerebral injury or pathologic intracranial hemorrhage). In addition, we selected anti-Pan-Cadherin (construction protein of adherent junctions on the intercalated disc) and PHA-E+L/Bio, to detect the integration of myocardial mechanical coupling and membranes (applying affinityhistochemistry, AHC) respectively.
Results:
(1) Phosphorylated Cx43 positive staining was almost invisible in Group I, II and III or scattered in sarcoplasm in few samples; but it was assembling at the IDs clearly in group IV and V. (2) Strongly positive staining of Pan-Cadherin could be observed at the IDs and (3) integrated myocardial membranes were found in all samples.
Conclusion:
These findings suggested that compared with the control groups, the integration of myocardial mechanical coupling and membranes did not alter in AMI. But Cx43, the key protein of electrical coupling on myocardial gap junctions, occurred dephosphorylation remarkably in AMI. Thus applying IHC techniques to detect the Cx43 dephosphorylation in human left ventricular myocardium maybe useful to recognize the onset of arrhythmia in AMI, especially in SCD whose myocardium without apparent morphological changes.
