lithium-chloride and Myocardial-Ischemia

The growth arrest- and DNA-damage inducible protein 153 (GADD153) regulates both apoptosis and inflammatory response. Importantly, glycogen synthase kinase-3β (GSK-3β) may provide a mechanistic link for cellular expression of GADD153, inflammatory response, and cell death. We previously showed that pressure overload exacerbates myocardial ischemia reperfusion injury associated with significant reduction in phosphorylated (inactive) GSK-3β. This raises the possibility that pressure overload, through a GSK-3β-dependent mechanism, increases GADD153 expression, thereby upregulating inflammatory cytokine production and contributing to worsening of myocardial ischemia reperfusion injury. Accordingly, Langendorff-perfused rat hearts were subjected to global ischemia reperfusion protocol in the absence or presence of the GSK-3β inhibitor, lithium chloride (1 mmol/L), with perfusion pressure set at 80 or 160 cmH(2)O; normoxic hearts served as controls. Compared with normoxia, an ischemia reperfusion insult increased expressions of proinflammatory cytokines, γH2AX, and GADD153 in association with increased cell death. In the ischemic-reperfused hearts, pressure overload did the following: (1) reduced interleukin-10 but increased interleukin-17 (cardiomyocytes), without affecting interleukin-23; (2) increased expressions of γH2AX and GADD153; (3) decreased 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) aggregates but increased JC-1 monomers (suggestive of reduced mitochondrial membrane potential, ψ(m)); and (4) increased annexin V immunostaining as well as apoptotic and necrotic cell death. Treatment with lithium chloride caused a robust increase in interleukin-10, preserved ψ(m), and markedly decreased all other parameters with the effect being most prominent for hearts perfused at the high pressure. In conclusion, pressure overload, via a GSK-3β-dependent mechanism, exacerbates cell death in the isolated ischemic-reperfused heart involving regulation of inflammatory response, DNA injury, and GADD153 expression.

Topics: Animals; Cytokines; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Heart; Histones; Hypoxia; Lithium Chloride; Male; Membrane Potential, Mitochondrial; Myocardial Ischemia; Myocardial Reperfusion; Myocardial Reperfusion Injury; Myocardium; Phosphoproteins; Rats; Rats, Sprague-Dawley; Transcription Factor CHOP

The aim of this study was to elucidate the mechanism of enhanced inositol phosphate metabolism during reperfusion. Inositol phosphate stores were prelabelled by perfusing isolated rat hearts for 1 h with [3H]inositol (1.5 microCi/ml). LiCl (10 mM) and prazosin (0.3 microM) were subsequently added 15 min before (i) 20 min control perfusion; (ii) 20 min normothermic ischaemic cardiac arrest (NICA); (iii) 20 min NICA followed by 1 min reperfusion. The ventricles were freeze-clamped before determination of isotopical incorporation of [3H]inositol into the inositol phosphates (Dowex anion exchange chromatography) and InsP3 levels (Amersham InsP3 assay system). In addition, noradrenaline release into the perfusate was also assessed (HPLC and electrochemical detection). The results showed: (i) increased noradrenaline release into the perfusate immediately after the onset of reperfusion; (ii) significant depression of [3H]inositol incorporation into inositol phosphates and InsP3 levels after 20 min NICA; (iii) reperfusion caused an immediate significant increase in isotopical incorporation of [3H]inositol into inositol phosphates as well as InsP3 levels; (iv) the alpha 1-adrenergic blocker, prazosin (0.3 microM), completely inhibited the reperfusion-induced increase in inositol phosphate metabolism. These observations suggested that increased alpha 1-adrenergic receptor stimulation by noradrenaline might be responsible for the stimulation of ventricular inositol phosphate metabolism during postischaemic reperfusion.

Topics: Animals; Chlorides; Chromatography, High Pressure Liquid; Heart Ventricles; Inositol 1,4,5-Trisphosphate; Inositol Phosphates; Lithium; Lithium Chloride; Male; Myocardial Ischemia; Myocardial Reperfusion; Norepinephrine; Prazosin; Rats; Rats, Wistar; Receptors, Adrenergic, alpha