Inhibiting Protease-Activated Receptor 4 Limits Myocardial Ischemia/Reperfusion Injury in Rat Hearts by Unmasking Adenosine Signaling

Abstract

Harnessing endogenous cardioprotectants is a novel therapeutic strategy to combat ischemia/reperfusion (I/R) injury. Thrombin causes I/R injury, whereas exogenous adenosine prevents I/R injury. We hypothesized that blocking thrombin receptor activation with a protease-activated receptor (PAR) 4 antagonist would unmask the cardioprotective effects of endogenous adenosine. The protective role of two structurally unrelated PAR4 antagonists, trans-cinnamoyl-YPGKF-amide (tc-Y-NH 2 ) and palmitoyl-SGRRYGHALR-amide (P4pal10), were evaluated in two rat models of myocardial I/R injury. P4pal10 (10 g/kg) treatment before ischemia significantly decreased infarct size (IS) by 31, 21, and 19% when given before, during, and after ischemia in the in vivo model. tc-Y-NH 2 (5 M) treatment before ischemia decreased IS by 51% in the in vitro model and increased recovery of ventricular function by 26%. To assess whether the cardioprotective effects of PAR4 blockade were due to endogenous adenosine, isolated hearts were treated with a nonselective adenosine receptor blocker, 8-sulfaphenyltheophylline (8-SPT), and tc-Y-NH 2 before ischemia. 8-SPT abolished the protective effects of tc-Y-NH 2 but did not affect IS when given alone. Adenosine-mediated survival pathways were then explored. The cardioprotective effects of tc-Y-NH 2 were abolished by inhibition of Akt (wortmannin), extracellular signal-, and K ATP channels (glibenclamide). PD98059, L-NMA, and glibenclamide alone had no effect on cardioprotection in vitro. Furthermore, inhibition of mitochondrial K ATP channels [5-hydroxydecanoic acid (5-HD)] and sarcolemmal K ATP channels (sodium (5-(2-(5-chloro-2-methoxybenzamido)ethyl)-2-methoxyphenylsulfonyl)(methylcarbamothioyl)amide; HMR 1098) abolished P4pal10-induced cardioprotection in vivo. Thrombin receptor blockade by PAR4 inhibition provides protection against injury from myocardial I/R by unmasking adenosine receptor signaling and supports the hypothesis of a coupling between thrombin receptors and adenosine receptors.

Protease-activated receptors in cancer: A systematic review

“…Efforts to develop receptor inhibitors as compared to targeting thrombin are currently regarded as a priority. As outlined in Table V ( [134][135][136][137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152], substantial success has been achieved in the development of PAR1 and PAR4 antagonists.…”

Parstatin(1-26): The Putative Signal Peptide of Protease-Activated Receptor 1 Confers Potent Protection from Myocardial Ischemia-Reperfusion Injury

“…5-Hydroxydecanoic acid (5-HD) and HMR 1098 were dissolved in water, whereas all other agents were dissolved in DMSO. Doses selected for each agent were determined from prior studies (Strande et al, 2007(Strande et al, , 2008(Strande et al, , 2009Gross et al, 2008).…”

“…The area at risk from the left ventricle (n ϭ 6/group) was isolated after 5 min of reperfusion and immediately frozen in liquid nitrogen. Tissue homogenates and immunoblot analysis were performed by use of methods described previously (Strande et al, 2008). Membranes were incubated with a 1:500 to 1:1000 dilution of the primary antibody, anti-phospho-Akt (Ser473) or anti-phospho eNOS (Ser1177), from Cell Signaling Technology (Danvers, MA).…”

Studies on PEGylated Gold Nanoparticles Loaded with 5-Hydroxydecanoate for Chemo-Photothermal Therapy of Human Lung AdenocarcinomasIn Vitro

“…Generally speaking, the studies involving 5-HD largely focused on the protective mechanism in myocardial ischemia-reperfusion injury (MIRI) at present. 20,21 However, on the one hand whether 5-HD could induce human lung adenocarcinomas (A549) cells apoptosis is unknown, on the other hand, 5-HD has a number of undesirable side e®ects to normal tissue while it is delivered alone, in particular life-threatening heart damage. Therefore, human lung adenocarcinomas (A549) cells apoptosis induced by 5-HD and 5-HD loaded on Au NPs-PEG was studied.…”