[Early stages of myocardial infarct studied by opitcal methods].

The hearts of 45 dogs were investigated at times from 10 minutes to 24 hours following ligation of the anterior interventricular branch of the left coronary artery. The material was fixed in formalin and embedded in parafin. It was established that at early stages of experimental myocardial infarction in the zone of eschemia there took place eschemic zone various foms of contactural damages, lumpy decmposition, relaxation and sarcoplasmic matrix.

[Use of formaldehyde with pH 8 0 as a fixative for electron and fluorescence microscopy].

For fixation of the material to be investigated at the light and ultrastuctural level the author suggests to use 4% formaldehyde obtained by depolymerization of paraform on 0.1 M phosphate buffer with end pH 8.0 of the solution.

[The effect of acetylsalicylic acid on the development of infarct-like myocardial necroses experimentally induced in rats by a single administration of novodrin (isopropylnoreadrenaline)].

It appeared that acetylsalicylic acid considerably decreased both development of the infarction-like foci of necrosis and primary damage of the myocardial cells experimentally induced in animals by direct action of novodrin and expressed in the course of the first hour. This led to the supposition that acetylsalicylic acid not only prevented platelet aggregation, but also increased the resistance of the myocardial cells to the injurious action of catecholamines.

Acute lesion of rat myocardium by a single injection of cobalt dichloride.

The formation of infarctoid areas in rat myocardium following intraperitoneal injection of cobalt dichloride (30 mg/kg) is connected with metabolic (toxic) and ischaemic lesions of myocardial cells. The ischaemic lesions are sequelae of thrombosis taking place after 3-8 hours in consequence of thrombocytic aggregation in the capillary lumen. With the aid of polarization and electron microscopy, the myocardial-cell changes in the affected zones were classed into four morphological types, as follows: contracture type, intracellular myocytolysis, primary clumpy disintegration of myofibrils, and intravital autolysis of ischaemized cells.