Introduction Chronic obstructive pulmonary disease (COPD) is the 3rd leading

cause of death worldwide (Qureshi, Sharafkhaneh and Hanania2014). COPD is a progressive condition with irreversible airwaydamage, and includes conditions such as emphysema and chronicbronchitis (Daheshia 2005). Patients are often at a greater risk ofcardiovascular complications such as ischaemic heart disease, dueto lifestyle associated risk factors, such as smoking.

COPD patients are prescribed bronchodilators to improve lungfunction. Often, a combination of pharmacological therapies areprescribed, including β2 adrenoceptor agonists and muscarinicreceptor antagonists to alleviate bronchoconstriction.

Recent clinical studies have associated the use of muscarinicreceptor antagonists such as the short acting, ipratropium bromideand the long acting, tiotropium bromide with an increased risk ofadverse cardiovascular effects, including myocardial infarction andstroke in COPD patients (Singh, Loke and Furberg 2008; Hilleman etal. 2009). Previous studies from our group have shown thatipratropium exacerbates myocardial injury in pre-clinical models ofischaemia/reperfusion injury (Harvey, Hussain and Maddock 2014).

These clinical findings have prompted the urgent need to assess thecardiac safety profile of long acting muscarinic receptor antagonists(LAMAs), in experimental models of myocardialischaemia/reperfusion injury.

Aim To characterise the cardiac safety profiles of LAMAs in in-vitro

models of myocardial ischaemia/reperfusion injury.

Methods Briefly: Isolated perfused hearts were subjected to 35 min of

regional ischaemia followed by reperfusion for 120 minutes (figure1). For the drug treated groups; either Glycopyrronium, Aclidinium,Tiotropium or Umeclidinium (10μM-1nM) was administeredthroughout the reperfusion period.

At the end of the experiment, hearts were subjected to TTC stainingfor infarct-to-risk ratio (%) analysis. Hearts that underwentischaemia were also stained with Evans blue.

Figure 1: The experimental protocols used for the Langendorff models. KH – Krebs-Henseleit buffer.

Cardiac Safety Profiles of Long Acting Muscarinic Receptor Antagonists

Used in the Treatment of Chronic Obstructive Pulmonary Disease Shabana Cassambai, Sadie Dean, Christopher J Mee, Afthab Hussain

Faculty Research Centre - Applied Biological and Exercise Sciences, Coventry University, CV1 5FB

ConclusionThis is the first pre-clinical study to suggest that the administration of LAMAs during reperfusion, exacerbates myocardial ischaemia/reperfusion injury in anin-vitro isolated heart model. In order to determine the signalling mechanisms underlying this exacerbated myocardial injury; further studies examining theactivation of cell death pathways and molecular changes associated with drug administration are urgently required.

Results

Figure 2: Glycopyrronium Bromide (10μM-1nM) administration does not significantly increaseInfarct size to risk ratio. Mean ± SEM n=4, ****P<0.0001 vs. normoxia.

Figure 3 : Aclidinium Bromide administration significantly increases infarct development atconcentrations of 10μM, 10nM and 1nM. Mean ± SEM n=3, **** P<0.0001 vs. normoxia, ###P<0.001 vs. IR, ## P<0.01 vs. IR, $ P<0.05 vs. IR+AB (10μM), € P<0.05 vs. IR+AB (1μM), ^^ P<0.01vs. IR+AB (100nM).

Figure 4: Tiotropium Bromide administration during reperfusion results in a significant increasein infarct development at all concentrations. Mean ± SEM n=3, **** P<0.0001 vs. normoxia, ####P<0.0001 vs. IR, ### P<0.001 vs. IR, ## P<0.01 vs. IR.

Figure 5: Administration of Umeclidinium Bromide (100nM, 10nM and 1nM) throughoutreperfusion increases infarct size to risk ratio (%). Mean ± SEM n=4, **** P<0.0001 vs. normoxia,#### P<0.0001 vs. IR, €€€€ P<0.0001 vs. IR+UB (1μM).

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