Ghouri, I. A., Kelly, A., Salerno, S., Garten, K., Stølen, T., Kemi, O.-J. and Smith, G. L. (2018) Characterization of electrical activity in post-myocardial infarction scar tissue in rat hearts using multiphoton microscopy. Frontiers in Physiology, 9, 1454. (doi: 10.3389/fphys.2018.01454) (PMID:30386255) (PMCID:PMC6199960)
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Abstract
Background: The origin of electrical behavior in post-myocardial infarction scar tissue is still under debate. This study aims to examine the extent and nature of the residual electrical activity within a stabilized ventricular infarct scar. Methods and Results: An apical infarct was induced in the left ventricle of Wistar rats by coronary artery occlusion. Five weeks post-procedure, hearts were Langendorff-perfused, and optically mapped using di-4-ANEPPS. Widefield imaging of optical action potentials (APs) on the left ventricular epicardial surface revealed uniform areas of electrical activity in both normal zone (NZ) and infarct border zone (BZ), but only limited areas of low-amplitude signals in the infarct zone (IZ). 2-photon (2P) excitation of di-4-ANEPPS and Fura-2/AM at discrete layers in the NZ revealed APs and Ca2+ transients (CaTs) to 500-600 μm below the epicardial surface. 2P imaging in the BZ revealed superficial connective tissue structures lacking APs or CaTs. At depths greater than approximately 300 μm, myocardial structures were evident that supported normal APs and CaTs. In the IZ, although 2P imaging did not reveal clear myocardial structures, low-amplitude AP signals were recorded at discrete layers. No discernible Ca2+ signals could be detected in the IZ. AP rise times in BZ were slower than NZ (3.50 ± 0.50 ms vs. 2.23 ± 0.28 ms) and further slowed in IZ (9.13 ± 0.56 ms). Widefield measurements of activation delay between NZ and BZ showed negligible difference (3.37 ± 1.55 ms), while delay values in IZ showed large variation (11.88 ± 9.43 ms). Conclusion: These AP measurements indicate that BZ consists of an electrically inert scar above relatively normal myocardium. Discrete areas/layers of IZ displayed entrained APs with altered electrophysiology, but the structure of this tissue remains to be elucidated.
| Item Type: | Articles |
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| Additional Information: | This work was supported by a European Union Framework Programme 7 grant (Grant No. HEALTH-F2-2009-241526) and a British Heart Foundation project grant (Grant No. PG/09/107). AK is funded by a British Heart Foundation project grant (Grant No. PG/17/12/32847). SS is funded by the Norwegian Council for Cardiac Research. |
| Keywords: | Intracellular calcium, myocardial infarction, two-photon microscopy, optical mapping, border zone |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Smith, Professor Godfrey and Kemi, Dr Ole and Kelly, Dr Allen and Ghouri, Dr Iffath |
| Authors: | Ghouri, I. A., Kelly, A., Salerno, S., Garten, K., Stølen, T., Kemi, O.-J., and Smith, G. L. |
| College/School: | College of Medical Veterinary and Life Sciences College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health |
| Journal Name: | Frontiers in Physiology |
| Publisher: | Frontiers Media |
| ISSN: | 1664-042X |
| ISSN (Online): | 1664-042X |
| Copyright Holders: | Copyright © 2018 The Authors |
| First Published: | First published in Frontiers in Physiology 9:1454 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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