Modulation of Purinergic Receptors is Protective Against Hypoxia/Reoxygenation Injury in AC16 Cardiomyocytes

It has been reported that extracellular ATP concentrations during postischemic reperfusion activate cardiomyocyte purinergic receptors thus modulating both cardiac function and survival. This study is purported to assess the effects of purinergic modulation on the viability of a adult human ventricular derived cell line (AC16 cardiomyocytes) viability after hypoxia/reoxygenation (H/R). Cultured AC16 cardiomyocytes were subjected to 5 hours of hypoxia in a hypoxic chamber or by mineral oil layering. During the 1 h reoxygenation cells received no additional intervention or were treated with increasing ATP doses (10mM, 100mM and 1 mM) in the presence vs. the absence of either 100mM or 300mM suramin (a purinergic inhibitor). Cell viability was evaluated by MTT colorimetric assay. Administration of 100mM ATP (but not with 10mM) induced a significant improvement of cellular relative viability (RV) in experiments performed in the hypoxic chamber, an effect that was completely inhibited by suramin. Treatment with 1mM ATP and 1mM ATP (but not with 10mM and 100mM), elicited a significant increase of cellular RV equally in cardiomyocytes belonging to the control group and the ones exposed to both H/R protocols, regardless the presence or the absence of the purinergic inhibitor (100mM or 300mM). In conclusion, purinergic stimulation elicits cardioprotection in the settings of H/R injury, the effect being dependent both on the ATP concentration and the type/severity of the hypoxic insult