An inhibitor of poly (ADP-ribose) synthetase activity reduces contractile dysfunction and preserves high energy phosphate levels during reperfusion of the ischaemic rat heart

摘要

class="enumerated" style="list-style-type:decimal">The cardioprotective properties of inhibition of poly (ADP-ribose) synthetase (PARS) were investigated in the isolated perfused heart of the rat. Hearts were perfused in the Langendorff mode and subjected to 23 min total global ischaemia and reperfused for 60 min.Left ventricular function was assessed by means of an intra-ventricular balloon. High energy phosphates were measured by ³¹P-NMR spectroscopy. Intracellular levels of NAD were measured by capillary electrophoresis of perchloric acid extracts of hearts at the end of reperfusion.Reperfusion in the presence of the PARS inhibitor 1,5 didroxyisoquinoline (ISO, 100 μM) attenuated the mechanical dysfunction observed following 1 h of reperfusion; 27±13 and 65±8% recovery of preischaemic rate pressure product for control and 100 μM ISO, respectively.This cardioprotection was accompanied by a preservation of intracellular high-energy phosphates during reperfusion; 38±2 vs 58±4% (P<0.05) of preischaemic levels of phosphocreatine (PCr) for control and 100 μM ISO respectively and 23±1 vs 31±3% (P<0.05) of preischaemic levels of ATP for control and 100 μM ISO respectively.Cellular levels of NAD were higher in ISO treated hearts at the end of reperfusion; 2.56±0.45 vs 4.76±1.12 μmoles g⁻¹ dry weight (P<0.05) for control and ISO treated.These results demonstrate that the cardioprotection afforded by inhibition of PARS activity with ISO is accompanied by a preservation of high-energy phosphates and cellular NAD levels and suggest that the mechanism responsible for this cardioprotection may involve prevention of intracellular ATP depletion.