Pearce, Lucie Elizabeth;
(2024)
The Role of Novel Rock1/2 Inhibitors in Coronary Circulation & Myocardial Reperfusion/Injury.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
INTRODUCTION: ROCK1/2 (Rho kinases 1 and 2) are important intracellular kinases which regulate apoptosis, vascular smooth muscle contraction and organisation of the cytoskeleton (Shimokawa et al., 2016). Fasudil (a ROCK1 and 2 inhibitor) is cardioprotective in vivo during myocardial ischaemia/reperfusion (I/R). The drug has been used in clinical practice to treat vasospasm in subarachnoid haemorrhage (Satoh et al., 2014). However, it is not established whether ROCK1 or ROCK2 is cardioprotective. Vasospasm is a known pathology of ischaemic microvascular obstruction (MVO). At present there are no gold standard therapies for MVO, despite its poor prognosis (Niccoli et al., 2016). This thesis aims to investigate the role of the ROCK2 isoform in myocardial and coronary circulation protection. AIMS: To investigate i) the expression of ROCK2 mRNA in the heart and its role in myocardial I/R using selective ROCK2 inhibitors and genetically modified mice, ii) the role of ROCK2 inhibitors as vasodilators and therefore potential MVO drugs. METHODS: An RNAscope assay quantified ROCK1/2 expression in whole rat hearts. Vascular myography studies were performed to investigate arterial response to ROCKi. Male Sprague Dawley rats (250-350g) underwent I/R by LAD ligation for 30/180-minutes. 15-minutes prior to reperfusion either selective ROCK2 inhibitor or DMSO control were administered I.P. Hearts were stained with TTC to measure IS% and Thioflavin S to measure MVO%. ROCK2 (+/-) C57B6/J mice were subject to 30/120 minutes of I/R using transient LAD infarction. RESULTS: ROCK2 mRNA expression was greater than ROCK1 mRNA expression in whole hearts and coronary vasculature (p=0.003, p=0.03).10mg/kg Fasudil (ROCK1/2 inhibitor) reduced infarct size in vivo (34.5±5.7 vs 55.8±4.7,p=0.02, n=6), however 100mg/kg of the selective ROCK2 inhibitor, KD025, did not (43.7±5.5 vs 48.3±4.9, p=0.87, n=8). KD025 did not demonstrate vasodilatory potential ex vivo. Following I/R, no significant difference in IS% was observed between genotypes in mice (ROCK2+/- 34.4±4.5 vs WT 37.6±6.6, p=0.70, n=6). 100mg/kg KD025 (ROCK2i) reduced MVO% in vivo (21.8±2.5 vs 32.2±1.8, p=0.04, n=8) as did Fasudil 3mg/kg (19.2±4.1 vs 32.2±1.8,p=0.01, n=6). CONCLUSION: Inhibition of both ROCK1 and 2 with Fasudil was cardioprotective, however selective ROCK2 inhibition and ROCK2 KO did not reduce IS%. This suggests that the ROCK1 isoform may be more important in myocardial protection.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | The Role of Novel Rock1/2 Inhibitors in Coronary Circulation & Myocardial Reperfusion/Injury |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10196580 |
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