Rapid kinetics of changes in oxygen consumption rate in thrombin-stimulated platelets measured by high-resolution respirometry

Alice P Sowton,Sarah L Millington-Burgess,Andrew J Murray,Matthew T Harper

doi:10.1016/j.bbrc.2018.08.031

Alice P Sowton, Sarah L Millington-Burgess + Show 2 more

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https://doi.org/10.1016/j.bbrc.2018.08.031

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Abstract

Platelet activation plays a key role in normal haemostasis and pathological thrombosis. Platelet activation is rapid; within minutes of stimulation, platelets generate bioactive phospholipids, secrete their granule contents, activate integrins and aggregate together to form a haemostatic plug. These events are dependent on ATP synthesis. Mitochondrial function in platelets from healthy volunteers and patients with a range of diseases indicate an important role for oxygen consumption in oxidative phosphorylation in normal and pathological function. Platelets also consume oxygen during oxidation reactions, such as cyclooxygenase-dependent thromboxane A2 synthesis. In this study, we used high-resolution respirometry to investigate rapid changes in oxygen consumption during platelet activation. We demonstrated a rapid, transient increase in oxygen consumption rate within minutes of platelet stimulation by the physiological activator, thrombin. This was partly inhibited by aspirin and by oligomycin. This shows that high resolution respirometry can provide information regarding rapid and dynamic changes in oxygen consumption during platelet activation.

Highlights

Platelet activation is central to haemostasis and arterial thrombosis [1]
Platelet activation requires ATP, which is provided by increased mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis [2e5]
Pioneering experiments starting in the 1970s using Clarktype oxygen electrodes showed that platelet activation with a range of physiological stimuli triggers a rapid increase in O2 consumption, attributed to increased mitochondrial OXPHOS and oxidation of arachidonic acid by cyclooxygenase (COX; inhibited by aspirin) [6,7]

Summary

Introduction

Platelets adhere at sites of vascular injury, generate and release bioactive phospholipids, release their granule contents through exocytosis, and activate their major integrin, aIIbb. Platelets adhere at sites of vascular injury, generate and release bioactive phospholipids, release their granule contents through exocytosis, and activate their major integrin, aIIbb3 These events lead to recruitment of further platelets and platelet aggregation, forming a haemostatic plug or occlusive thrombus [1]. Platelet activation requires ATP, which is provided by increased mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis [2e5]. Pioneering experiments starting in the 1970s using Clarktype oxygen electrodes showed that platelet activation with a range of physiological stimuli triggers a rapid increase in O2 consumption, attributed to increased mitochondrial OXPHOS (inhibited by oligomycin) and oxidation of arachidonic acid by cyclooxygenase (COX; inhibited by aspirin) [6,7]. The resolution achievable with Clarktype electrodes is relatively low compared to high-resolution approaches currently available

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