[Degree of granularity of the atrial cardiocytes. Morphometric study in rats subjected to different types of water and sodium load (author's transl)].

Morphometric analysis was applied to the evaluation of the atrial cardiocytes specific granules, in rats subjected to different types of water and sodium load. In control animals, the right atrium is more granulated than the left one and the interauricular septum. Ipsilateral atrium and auricle have the same index of granularity. Five types of water and sodium load were tested - I. Full water restriction - II. Sodium restriction with normal water intake - III. Controls - IV. Sodium overloading - V. Sodium and Doca overloading. From groups I to V, the index of granularity decreases progressively. The same phenomenon does not appear in the left atrium, except for the group II (sodium restriction) whose index is higher (p less than 0.001) than in the other groups. These data are not incompatible with the existence of a relationship between the presence of atrial specific granules and the atrial volosensitivity. An analogy between these cells and the myopithelioid cells of the juxtaglomerular apparatus is then suggested.