Morinda Officinalis Oligose On Myocardial Ischemical-Reperfusion Injury In Rats

Ischemical reperfusion injury (IRI) has attracted a lot of interest in the cardiovascular studies since firstly introduced in the 1970s. It has been shown that several intrinsic factors, such as oxygen free radical, calcium overload, abnormal energy metabolism of cardiac muscle fibers, vascular endothelial cell(VEC)? nitric oxide (NO), neutrophile granulocyte and apoptosis, contributed to the development of reperfusion injury. Decreasing the activity of these factors may provide an effective way to prevent or decrease the damage caused by IRI.Pharmacologic preconditioning protection against heart injury is trigged by medicine which can simulate beneficical effects of cardiac ischemic preconditioning. At present, it has become a research tendency, which will be helpful to probe the mechanism of IRI and develop new drugs resisting ischemical reperfusion injury. Recently, there has been great development in Chinese medicine extractive to protect myocardium against ischemia reperfusion injury. The extract of Morida officinalls has been reported to increase the activity antioxidase in brain and liver tissue but there has had few reports on myocardium; and has favourable capacity of removing superoxide anion and hydroxy radical. The investigation involve in preconditioning rat hearts with Morinda officinalis oligose (MOO) and with Di-ao-xin-xue-kang (DK) as positive control drug, constructing the model of myocardial I/R, to observe the effect of MOO on myocardial IRI. MethodsThree different concentrations of MOO 0.28g/ml, 0.14g/ml and 0.07g/ml were prepared and DK Capsule content was mixed with 0.5% sodium carboxymethyl cellulose into suspension with the concentration of 0.07g/ml. 96 Wistar rats (half in male and female) were randomly divided into 6 groups, namely sham ligation(Sham) group, myocardial ischemia/reperfusion (I/R) model group, positive control drug (DK) group, and three different doses of MOO 2.8g/kg, 1.4g/kg, 0.7g/kg groups. The rats in DK and three different doses of MOO groups were given 10ml/kg q.d. DK suspension and three concentration of MOO respectively by intragastric administration for 7 days, and the rats in Sham and I/R model group were given 10ml/kg q.d distilled water. After 1 hour of the last intragastric administration, all rats were subjected to opening chest then the left anterior desending (LAD) of coronary artery was ligated for 30 min and unclamped for 90min except the rats with only thread-drawing in Sham group. Hemodynamics, ischemic zone size and infarct size (IZS and IS) of myocardium and scores of cardiac arrhythmia were measured. One half rats of every group were injected Evans blue then the hearts were taken out. After refrigeration, the frozen hearts were sliced into 1.5mm sections, and the slices were incubated in 1% triphenyltetrazolium chloride (TTC). The slices were immersed in 10% formalin overnight, the infracted myocardium was dissected from the IZS under the illumination of a dissecting microscope. IS, IZS and left ventricle were weighed, myocardial homogenate was maken and then superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), Na⁺-K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase and creatine kinase (CK) were measured in other half rats of every group.Results(1) hemodynamics myocardial functional parameters, such as left ventricular systolic pressure (LVSP), maximum positive and negative change in pressure (±dp/dt) and left ventricular end-diastolic pressure (LVEDP) were similar among the six groups before the ligation of LAD (P>0.05). In the ischemic/reperfusion especially reperfusion period, LVSP and±dp/dt were significantly lower in the VR group as compared with the Sham group (P<0.01), but markedly higher in the DK and MOO2.8g/kg groups when compaed with I/R group (P<0.01).(2) Scores of arrhythmia Except MOO 0.7g/kg group, the scores of DK and MOO2.8g/kg, 1.4g/kg groups were obviously lower compared with I/R (P<0.01) duringischemic period and reperfused period; the scores of DK and MOO 2.8g/kg were notsignificantly different during ischemic period and reperfusion period (P>0.05).(3) Ischemic zone size and infarct size IZS and IS were significantly lower in Sham,DK, MOO 2.8g/kg, 1.4g/kg, 0.7g/kg groups than I/R group (P<0.01).(4) SOD, CAT, GSH-Px and MDA Compared with Sham group, the level ofmyocardial SOD, CAT, GSH-Px were significantly decreased but MDA increasedmarkedly in the I/R group (P<0.01); The level of myocardial SOD, CAT, GSH-Px inDK, MOO 2.8g/kg, 1.4g/kg, 0.7g/kg groups were significantly higher but the level ofMDA were lower than in the VR group (P<0.01).(5) Na⁺-K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase and CK The level of myocardialNa⁺-K⁺-ATPase , Ca²⁺-ATPase and Mg²⁺-ATPase in the I/R group were lower thanSham group but CK increased markedly in the I/R group(P<0.01). Compared with VRgroup, the level of myocardial Na⁺-K⁺-ATPase, Ca²⁺-ATPase and Mg²⁺-ATPase weresignificantly increased but CK decreased markedly in DK, MOO 2.8g/kg, 1.4g/kg,0.7g/kg groups (P<0.01).The level of myocardial Na⁺-K⁺-ATPase, Ca²⁺-ATPase,Mg²⁺-ATPase and CK in DK and MOO 2.8g/kg groups were not significantlydifferent (P>0.05).Conclusion1. These results demonstrate that pretreatment of rats with Morinda Officinalis Oligose has cardiac protective effects. It can obviously improve hemodynamics of heart, minimize myocardial infarct size and reduce the incidence rate of cardiac arrhythmia.2. Morinda Officinalis Oligose increases the activity of antioxidase and inhibites lipid to peroxidate in rat hearts when they are subjected to ischemia/reperfusion injury.3. Morinda Officinalis Oligose increases the level of myocardic Na⁺-K⁺-ATPase, Ca²⁺-ATPase and Mg²⁺-ATPase, reduces markedly the activity of CK in rats, that is one of the mechanisms of its cardial protective effects.4. Morinda Officinalis Oligose has cardiac protective effects and increases antioxidation, which are similar to DK.