Adenosine A1 and A3 receptor agonists reduce hypoxic injury through the involvement of P38 MAPK

Abstract

Activation of either the A(1) adenosine receptor (A(1)R) or the A(3) adenosine receptor (A(3)R), by their specific agonists CCPA and Cl-IB-MECA, respectively, protects cardiac cells in culture against ischemic injury. Yet the full protective mechanism remains unclear. In this study, we therefore examined the involvement of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK) phosphorylation in this protective intracellular signaling mechanism. Furthermore, we investigated whether p38 MAPK phosphorylation occurs upstream or downstream from the opening of mitochondrial ATP-sensitive potassium (K(ATP)) channels. The role of p38 MAPK activation in the intracellular signaling process was studied in cultured cardiomyocytes subjected to hypoxia, that were pretreated with CCPA or Cl-IB-MECA or diazoxide (a mitochondrial K(ATP) channel opener) with and without SB203580 (a specific inhibitor of phosphorylated p38 MAPK). Cardiomyocytes were also pretreated with anisomycin (p38 MAPK activator) with and without 5-hydroxy decanoic acid (5HD) (a mitochondrial K(ATP) channel blocker). SB203580 together with the CCPA, Cl-IB-MECA or diazoxide abrogated the protection against hypoxia as shown by the level of ATP, lactate dehydrogenase (LDH) release, and propidium iodide (PI) staining. Anisomycin protected the cardiomyocytes against ischemic injury and this protection was abrogated by SB203580 but not by 5HD. Conclusions Activation of A(1)R or A(3)R by CCPA or Cl-IB-MECA, respectively, protects cardiomyocytes from hypoxia via phosphorylation of p38 MAPK, which is located downstream from the mitochondrial K(ATP) channel opening. Elucidating the signaling pathway by which adenosine receptor agonists protect cardiomyocytes from hypoxic damage, will facilitate the development of anti ischemic drugs.

The A3Adenosine Receptor: History and Perspectives

“…This pathway has also been observed in A 3 AR-stimulated activity of antidepressant-sensitive serotonin transporters (Zhu et al, 2011). A 3 AR activation protects cardiomyocytes from hypoxia via phosphorylation of p38 MAPK, located downstream of the mitochondrial K ATP channel opening (Leshem-Lev et al, 2010). Accordingly, increased phosphorylation of p38 has been found after Cl-IB-MECA treatment, which proves beneficial, protecting the rat heart subjected to ischemia (Hochhauser et al, 2007).…”

Purinergic Signaling and Blood Vessels in Health and Disease

“…Endogenous adenosine makes a significant contribution to A 1 agonistmediated prevention of necrosis in a cardiac cell model of ischemia by cooperative interactions with both A 2A and A 2B receptors, but does not play a role in A 3 agonistmediated protection (Urmaliya et al, 2009;Methner et al, 2010). It was reported that A 1 and A 3 receptor agonists reduce hypoxic injury through the involvement of p38 MAPK (Leshem-Lev et al, 2010). Adenosine stimulates the recruitment of endothelial progenitor cells to the ischemic heart to enhance revascularization (Goretti et al, 2012).…”

Cardiac purinergic signalling in health and disease

“…It has been reported that A1R and A3R agonists reduce hypoxic injury through the involvement of p38 MAPK [553]. In situ ischaemic pre-conditioning conferred cardioprotection in A1R, A2AR and A3R, but not A2BR knockout mice, or in wild-type mice after inhibition of A2BR, and thus, it was suggested that 5′-nucleotidase and A2BR agonists might be considered as therapeutic agents for myocardial ischaemia [554,555].…”