[Ultrastructural features of hormone-producing cardiomyocytes under certain experimental and clinical conditions]

Ultrastructural peculiarities of the cardiac hormone secretion (atrial natriiuretic factor) have been studied under certain experimental and clinical conditions. In atrial myocytes of intact dogs degree of the Golgi complex development, where the hormone is formed, amount of endocrinic granules and their qualitative composition vary considerably even in neighbouring cells. These structures reach a very great development in myocytes of the left atrium in persons with mitral stenosis, where certain anomaleously large secretory granules, resembling lyosomes are formed. When the organism is cooled up to 27-28 degrees C and the blood stream is interrupted in the experiment and along the course of a defect correction, amount of the secretory granules in cardiomyocytes decline significantly. The Golgi complex decreases, its cysterns become fragmented, their content is cleared. After warming up to the normal temperature there is no complete restoration of these structures. On the 3d day after the experiment in some cases signs of hypertrophy and elevated functional activity of the secretory structures appear. The ways of synthesis, accumulation and degradation of secretory granules in cardiomyocytes are followed, a classification of their ultrastructural varieties is suggested: forming, young, mature and dissolving forms. Together with the analysis of the Golgi complex, it helps to judge the endocrinic activity of cardiomyocytes.