The isolated perfused working rat heart model of
cardiopulmonary bypass and ischaemic
cardiac arrest has been used to investigate whether addition of various organic
anti-oxidants to the
St Thomas' Hospital cardioplegic solution can enhance the recovery of function of the rat myocardium after normothermic (37 degrees C) global ischaemic arrest. Five
anti-oxidants were studied: (i) ascorbate (1.0 and 10.0 mmol.litre-1), (ii)
methionine (1.0 and 10.0 mmol.litre-1), (iii)
reduced glutathione (1.0 and 10.0 mmol.litre-1), (iv)
dimethylthiourea (0.1, 1.0, 10.0 and 50.0 mmol.litre-1), (v) N-2-mercaptopropionyl
glycine (0.1, 1.0 and 10.0 mmol.litre-1). The recovery of aortic flow in control hearts which were free of
anti-oxidant was 50.7(SEM 0.5)%; ascorbate (1.0 or 10.0 mmol.litre-1) improved this recovery to 72.1(1.7) and 70.2(0.3)% respectively;
methionine (1.0 and 10.0 mmol.litre-1) improved the recovery to 74.1(5.7)% and 67.7(1.7)%, respectively;
reduced glutathione (1.0 and 10.0 mmol.litre-1) improved the recovery to 66.7(1.4)% and 74.0(1.7)% respectively. In further studies, the addition of
dimethylthiourea (0.1, 1.0 and 10.0 mmol.litre-1) to the
cardioplegic solution failed to improve recovery of aortic flow [47.3(8.0), 24.6(7.3), 48.0(7.7)% respectively] when compared to its
anti-oxidant free control value of 40.4(6.1)% and at a concentration of 50.0 mmol.litre-1 a very poor recovery of aortic flow of 7.7(4.8)% was observed. Mercaptopropionyl
glycine (0.1, 1.0 and 10.0 mmol.litre-1) also failed to improve the recovery of aortic flow [34.7(1.6), 34.7(7.7) and 25.6(5.4)% respectively.2+ Since
biological membranes are highly permeable to
dimethylthiourea and mercaptopropionyl
glycine, it is possible that they accumulate in the intracellular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)