THE DISTRIBUTION OF SUBMEMBRANE ACTIN-FIL AMENTS IN GRANULAR CELLS OFFROG URINARY-BLADDER

Distribution of submembrane actine filaments in granular cells of frog urinary bladder at basal or vasopressin stimulate water permeability was analyzed. Common methods of chemical fixation and immune electron microscopy were applied. The active nature of submembrane thin fibrils was proven by means of monoclonal antibodies against actine. It was s hown that the stimulation of water flows by vasopressin leads to a fou r-fold decrease in the density of immune gold label in the submembrane zone of granular cells. The drop in the content of actin filaments wa s due to the increase of Ca2+ concentration due to its release from sp ecific granules during the fusion of granule membranes with the apical membrane.