Changes in T1 and T2 Components in Global Ischemic Rat Heart Tissue

Water in biological tissue is affected by different processes during ischemia. Cell swelling and contracture alter distribution of myocardial water between the intracellular and extracellular compartments. This study aims to follow the progress of water redistribution by relaxographic measurements of multiple T1 and T2 components in excised rat heart tissue. Ventricular myocardium was excised and relaxography (Maran Ultra, Resonance Instruments Ltd, 23MHz, 37°C) was undertaken using Saturation Recovery (T1) every 2.5 min or Carr-Purcell-Meiboom-Gill (T2) every minute during the first 60 min after excision. The data were analysed using an Inverse Laplace Transformation revealing the distribution of relaxation components present in the myocardium as relaxograms. The use of T2-relaxography is promising in describing the status of ischemic progress and other processes altering the water distribution in biological tissue. In addition, the T1-value of tissue, influenced by the presence of intracellular manganese ions, could be used in combination with T2-relaxography to obtain information about equilibrium water exchange between intracellular and extracellular compartments during ischemic progress.