[Invasion of Escherichia coli A2 induces reorganization of actin microfilaments in Hep-2 cells].

Bacteria of spontaneously isolated non-pathogenic strain E. coli A2 have been previously shown to produce a new proteinase, referred to as protease ECP 32, which specifically cleaves actin (Khaitlina et al., 1988; Matveyev et al.

[Analysis of rat enterocyte ultrastructure during glucose absorption].

Electronmicroscopic study of rat enterocytes under glucose load (10-40 mM) has shown some changes of their structure: aggregations of intramembrane particles of the apical membrane in the microvilli region, the dilitation of lateral intercellular spaces below tight junction, the condensation of actin near tight and intermediate junctions. The presence of these changes and almost absolute absence of destructions in tight junctions organization indicate that the main pathway of the isotonic fluid containing glucose across leaky epithelium of rat small intestine is a transcellular one.

[An ultrastructural study of the apical cytoskeleton of the epithelial cells in the frog bladder with an ADH-dependent and an ADH-independent increase in osmotic permeability].

Immunocytochemical methods of electron and confocal microscopy were applied for studying the primembrane actin cytoskeleton in the frog urinary bladder granular cells, following the two actions: under the increased vasopressin-induced water permeability, and following autacoid removal by multiple changes of the Ringer solution around the serosa. In both cases similar changes have been revealed in the structure of the apical cytoskeleton and, in addition, a decrease in the density of its actin filament distribution was noticed.

[The ultrastructural characteristics of the epithelial cells in the frog bladder under the action of vasopressin and in a vasopressin-independent increase in permeability for water].

In experiments on isolated frog urinary bladders it has been found that the low basal level of water permeability in the absence of arginine-vasopressin (AVP) could be significantly increased when the serosal solution was changed several times every 15 min for a fresh Ringer solution. The electron microscopic study of these cells by the freeze-fracture technique showed that the enhancement of water permeability by AVP-independent manner was related to the appearance of intramembranous particle aggregates in luminal membrane of granular cell, that are usually observed only under the action of AVP. The immunocytochemical experiments with monoclonal antibodies against actin revealed the similarity in intracellular actin distribution under the action of AVP and AVP-independent increase of water permeability.