NMR Study of Damage on Isolated Perfused Rat Heart Exposed to Ischemia and Hypoxia

Myocardial ischemia is the most common and primary cause of myocardium damage. Numerous conventional techniques and methods have been developed for ischemia and reperfusion studies. However, because of damage to the heart sample, most of these techniques can not be used to continuously monitor the full dynamic course of the myocardial metabolic pathway. The nuclear magnetic resonnance (NMR) surface coil technique, which overcomes the limitations of conventional instrumentation, can be used to quantitatively study every stage of the perfused heart (especially after perfusion stoppage) continuously, dynamically, and without damage under normal or designed physiological conditions at the molecular level. In this paper, 31 P NMR was used to study the effects of ischemia and hypoxia on isolated perfused hearts. The results show that complete hypoxia caused more severe functional damage to the myocardial cells than complete ischemia.

Aortic and mitral valve replacement with retrograde perfusion in the beating heart

Objective To estimate the value of aortic valves and combined mitral valve replacement with retrograde perfusion in beating hearts.Methods Continuous retrograde coronary sinus perfusion with beating hearts was used in 83 patients undergoing aortic valve or aortic valve combined with mitral valve replacement,without application of cardioplegia.After aortic valve replacement,the retrograde perfusion wes changed to antegrade perfusion for mitral valve replacement or correction of the other deformities(group A).Cold blood cardioplegia solution(15℃)was infused at intervals in 20 cases(group B).The following parameters were tested:lactate,ET,CTn-T and MDA in blood;myocardial ultra-structure;and cardiac rhythm and cardiac output (co).Results All biochemical values increased after cardiopulmonary bypass(P ＜ 0.05 - 0.01).Empty and beating heart sinus rhythm was maintained in group A.Myocardial ultrastructure did not change significantly.The pump was stopped smoothly as the surgical procedure finished.No postoperative low cardiac output syndrome or arrhythmia was observed.Eight-one patients recovered smoothly,two died from renal failure or infective shock.When the pump stopped,all patients in group B were supported by 5 - 10 μg· kg-1· min-1 dopamine.Transient pacing was used in 9 patients.One patient died from low cardiac output syndrome.Conclusion This method is a good myocardial protection which simulates physiologic status.It is applicable to aortic valve and combined mitral valve replacement of patients with large heart or heart failure and long time aortic cross-clamping.Ideal clinical effect can be achieved.

Effect of hypertonic saline solution on the left ventricular functions of isolated hearts from burned rats

Objective: To study the effect of hypertonic saline solution on the left ventricular functions of isolated hearts from burned rats. Methods: Thirty six Wistar rats were used and divided into 4 groups: (1) normal hearts perfused with isotonic Krebs Henseleit solution; (2) normal hearts perfused with Krebs Henseleit solution which contained 215 mmol/L Na +; (3) hearts of rats suffered from 25% TBSA third degree burn and perfused with isotonic Krebs Henseleit solution; (4) hearts of the burned rats perfused with Krebs Henseleit solution which contained 215 mmol/L Na +. The systolic and diastolic functions of the left ventricle were observed.Results: During perfusion, there were very short periods of decrease in heart systolic and diastolic functions at first, but they recovered very soon and even became stronger than normal both in the normal and burned rats. The systolic and diastolic functions of the hearts increased very significantly when the perfusion solution was changed to isotonic solution from the hypertonic solutions. The effect of the hypertonic saline solution on the ventricular systolic and diastolic improvements was stronger in the hearts of the burned rats than that in the normal hearts. Conclusions: Hypertonic saline solution can directly affect myocardium and significantly improve the ventricular systolic and diastolic functions, especially in the hearts of the burned rats.

Cardioactive properties of Solanaceae plant extracts and pure glycoalkaloids on Zophobas atratus

Glycoalkaloids, the biologically active secondary metabolites produced by Solanaceae plants, are natural defenses against animals, insects and fungi. In this paper, the effects of glycoalkaloids present in extracts of Solanaceae plants （potato, tomato and black nightshade） or pure commercial glycoalkaloids on the coleopteran Zophobas atratus E were evaluated by in vitro and in vivo bioassays using heart experimental models. Each tested extract induced a dose-dependent cardioinhibitory effect. The perfusion of Zophobas atratus semi-isolated heart using the highest potato and tomato extract concentration （1 mmol/L） caused irreversible cardiac arrests, while extract from black nightshade pro- duced fast but reversible arrests. Pure commercial glycoalkaloids caused similar but less evident effects compared with extracts. Our results showed that the bioactivity of tested compounds depended on their structure and suggested the existence of synergistic interac- tions when combinations of the main glycoalkaloids of potato and black nightshade were used for trials. Surprisingly, injection of tomato and potato extracts in 1-day-old pupae of Zophobas atratus induced reversible positive chronotropic effects and decreased the duration of the both phases （anterograde and retrograde） of the heart contractile activity. Furthermore, these extracts affected the amplitude of the heart contractions.