Ultrastructure of cardiomyocytes in the peri-infarct zone during the treatment of experimental myocardial infarct in rats using the hexapeptide dalargin

The experiments on white rats with induced myocardial infarction have studied the influence of dalargin on the infarction size and peri-infarction zone ultrastructure. 24 hours later the decrease in the infarction zone size was detected in rats who had received dalargin in a dose of 50 and 100 micrograms/kg. In the peri-infarction zone the increase in glycogen quantity, the lower degree of lipid infiltration, the increase in mitochondrial number and mitochondrial energy effectiveness coefficient were noted, as compared to control animals. Sarcolemma of cardiomyocytes from the peri-infarction zone in rats on dalargin was impermeable for colloidal lanthanum. The decrease in the infarction size under the effect of dalargin is explained by its influence on the survival of cardiomyocytes in the peri-infarction zone.     

Protein-synthesizing function of the liver of rabbits in experimental myocardial infarct

The content of serum albumin in rabbit blood was found to be lowered within the first day after reproduction of experimental myocardial infarction. The rate and the level of translation of endogenous mRNA were studied in cell-free systems from normal rabbit liver and 6-12-24 h after experimental myocardial infarction. The decrease of the total protein synthesis in the crude cell-free system from the liver of experimental animals was shown to depend on the lack of energy supply rather than on the reduced activity of the protein-synthesizing apparatus. The relative drop of protein synthesis in the cell-free system with saturating concentration of ATP, GTP and creatine phosphate is likely to be connected with a decrease in the proportion of membrane-bound polysomes.     

Functioning of the monooxygenase system of the liver in experimental myocardial infarct

The experiments on rats have shown that coronary artery ligation reduces the content of microsomal cytochromes P-450 and b5 and causes amidopyrine-N-demethylation and aniline-p-hydroxylation disturbances that persist throughout a 3-week period of myocardial infarction. The investigation of spontaneous lipid peroxidation of microsomal membranes in myocardial infarction has shown that concentration of malonic dialdehyde in microsomal fraction significantly increased by the 7th day after coronary artery ligation, as compared to sham-operated rats.     

Lipid peroxidation in experimental myocardial infarct: the action of hyperbaric oxygenation

Rats with experimental myocardial infarction demonstrated decrease in the activity of superoxide dismutase and catalase and increase in the content of lipid peroxidation (LPO) products and Schiff bases both in and outside the area of necrosis. The combined ischemic damage and hyperbaric oxygenation resulted in the over additive effect of accumulation of LPO products in and outside the area of infarction. The data suggest that it is desirable to use antioxidants during hyperbaric oxygenation.     

The effect of hyperglycemia on the development of experimental myocardial infarct

Experiment on 72 dogs has shown that myocardial infarction (M1) against a background of hyperglycemia proceeds as shifts healing hyperactive MI. Shifts in carbohydrate metabolism results in disturbances of dynamics of the necrotic infarction zone processes that induces complications of healing changes in the content of myoglobin, creatine kinase, aspartateaminotransferase with MI against a background of hyperglycemia greatly differ from those typical of noncomplicated and complicated hyperactive MI.     

Pharmacokinetics of antipyrine, nifedipine and diazepam in experimental myocardial infarct]

It has been shown, that antipyrine, nifedipine, diazepam pharmacokinetics changes in different ways after myocardial infarction. On day 7, 14, and 21 after myocardial ischemia antipyrine T1/2 increased considerably, and antipyrine Cl and Kel decreased. Nifedipine T1/2 increased on day 7 only. There were no diazepam pharmacokinetic changes during restoration period. However, microsomal diazepam metabolism changed significantly. Diazepam hydroxylation increased on day 7 of myocardial infarction, and on day 14 and 21 did not differ from the control. Diazepam metabolites content changed considerably during restoration period. Under myocardial infarction cytochrome P-450 isoenzymes, oxidizing present substances seem to be altered to different extent.     

Combined use of hyperbaric oxygenation and antioxidants in the therapy of experimental myocardial infarct

In rabbits with experimental myocardial infarction, the combined use of hyperbaric oxygenation and ionol greatly potentiated the effect of the antioxidant on contractile function of the left ventricle, the time course of antioxidant lipid activity and superoxide dismutase activity of the myocardium.     

Effect of lidocaine and pyromecaine on the size of an experimental myocardial infarct

The experiments on rats with a 3-day myocardial infarction caused by the left coronary artery ligation have shown that multiple lidocaine and pyromecaine injections according to a given scheme decrease the size of the necrosis area. Drug effects were not related to their action on the blood supply of the ischemic area.     

Anti-arrhythmic effect of tetrodotoxin in the late stage of experimental myocardial infarct]

The action of tetrodotoxin (TT), blocking the fast sodium current, on arrhythmias that occurred 24 hours after occlusion of the coronary artery was studied in 10 dogs. TT injected intravenously in doses of 0.5--3.0 micrograms/kg significantly decreased the number of ventricular extrasystoles, and completely restored sinum rhythm in 4 animals. The maximum antiarrhythmic effect was noted 3 to 5 minutes after TT adminstration. It is suggested that arrhythmias and the antiarrhythmic effect of the drugs in the late stage of myocardial infarction are connected with the fast inward sodium current.     

Effect of Eleutherococcus on the subcellular structures of the heart in experimental myocardial infarct

The effect of Eleutherococcus on subcellular heart organization in rats with or without myocardial infarction was investigated. It was found that Eleutherococcus decreases ultrastructural lesions in the ischemic area, intensifies regeneration of subcellular structures and accelerates the recovery after myocardial infarction. The accumulation of glycogen, lipids and lysosomes is observed in lipocytes. It is suggested that positive effect of Eleutherococcus during myocardial infarction is related to lipid transformation into glycogen.     

The adenylic system in the brain structures of rats with experimental myocardial infarct

In rats experimental myocardial infarction, whether it was reproduced after a preliminary stress or in its absence, a reduction was found of ATP content initially appearing in the neocortex at the second day of the experiment. The deficit of providing of the energy in brain structures in a traditional variant of infarction reproduction increased still greater, and in the case of preliminary stressing the ATP content was reduced. Parallelly a characteristic change took place in the concentration of products of the fermentative ATP hydrolysis in the brain structures.     

Evaluation of the effectiveness of the long-term use of obzidan in experimental myocardial infarct

The authors performed a comprehensive study of the recovery processes in the myocardium after occlusion of the coronary artery in 126 white rats under the effect of a long-term treatment with propranolol (0.5 mg/kg). The drug reduced the size of necrosis by 2.6 times, significantly decreased the S-T segment rise on the ECG (up to 0.86 +/- 0.09 mV versus 1.85 +/- 0.15 mV, in untreated animals with myocardial infarction, P less than 0.001). The treated animals manifested the improvement of the morphologic status of the perinecrotic area and the myocardium of the posterior wall of the left ventricle. Cardiomyocytes preserved to a considerable degree the ultrastructure of the mitochondria, demonstrating an increase in DK and protein biosynthesis (up to 296.1%, P less than 0.001). At the same time the long-term treatment with propranolol led to an appreciable activation of intracellular reparative regeneration, acceleration of the renewal of organelles, thereby promoting a decrease in the hypertrophy of cardiomyocytes (by 22.1%, P less than 0.001) as compared with control. It is concluded that propranolol administered in a dose of 0.05 mg/kg favours rapid recovery of the functional structures of the myocardium.     

Reduction of experimental myocardial infarct size with hyperosmolar mannitol.

Hypertonic mannitol previously has been shown to improve cardiac function, increase collateral flow, and decrease epicardial ST segment elevation following coronary occlusion in anesthetized or awake dogs. The present study quantitates by morphologic techniques, the effect of hypertonic mannitol on infarct size. Ischemic injury was produced by proximal occlusion of the circumflex artery for 40 min and necrosis was assessed after 48 hr of reflow. One group of dogs was given isotonic saline and the other hypertonic mannitol beginning the infusions just prior to, during, and for a short period after the release of the circumflex coronary artery occlusion. Serum osmolality increased by approximately 40 mOsm in the mannitol group. The administration of hypertonic mannitol was associated with a 40-50% reduction in infarct size ventricular fibrillation during occlusion and following release of the circumflex coronary artery occlusion was greater in mannitol-treated dogs although the difference was not statistically significant. Thus, the data obtained in this study extend previous observations and provide direct evidence that hypertonic mannitol can reduce infarct size in dogs with temporary circumflex artery occlusion and reflow.