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.     

Pharmacokinetics of lincomycin in experimental animals]

When administered parentally, lincomycin satisfactorily penetrated into the organs and tissues of experimental animals. Pronounced tropism of the antibiotic in the bone tissue was observed which provided its recommendation for the treatment of osteomyelitis. The antibiotic was excreted with urine and bile.     

The effect of phosphoenolpyruvate on the course of the acute period in experimental myocardial infarct]

It was found in the experiments on dogs, that phosphoenolpyruvate decreased the level of regional metabolic acidosis, stabilized energy metabolism, cardiohemodynamics and enhanced the blood supply of the ischemic myocardium. Anti-ischemic effect of the phosphoenolpyruvate was more significant in comparison with fructose-1,6-diphosphate in isomolar doses.     

Ultrastructure of the sinus and atrioventricular nodes in experimental myocardial infarct

The ultrastructure of sinus and atrioventricular nodes was studied in white rats with experimental myocardial infarction. 24 hours after the induction of the disease mitochondrial enlargement characterized by the increase in their area, decrease in the number of cristae and the decline in the rate of mitochondrial energy effectiveness was detected. Different degrees of nuclear chromatin aggregation and membrane permeability for colloidal lanthanum were observed. Characteristic types of conduction cellular lesions were revealed in experimental myocardial infarction.     

The effect of strophanthin following administration of homocardiac antigen to animals with experimental myocardial infarct]

A study was made of strophanthin sensitivity and hemodynamic effect of glycosidein immunization of rabbits with a homocardiac antigen on the 1st, 3rd and 5th days after the reproduction of myocardial infarction. The titre of anticardiac autoantibodies proved to decrease on the 10th day after the ligation of the coronary artery, and also there was a sharp reduction of strophanthin sensitivity by the values of the minimal lethal dose and the toxic one (causing cardiac arrhthmia). Changes in strophanthin tolerance under conditions of administration of the antigen from the myocardium with infarction are associated with the intensive immunopathological shifts in the heart.     

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.     

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.