A method of isolation of apical membranous sheets from frog urinary bladder epithelium by stripping with gelatin.

We have developed a technique for recovering apical membranous sheets from amphibian urinary bladders by gelatin stripping. The tissue is mounted on a lucite support and the apical surface is first stuck onto a gelatin-coated glass slide at 30 degrees C. This sandwich is then chilled on ice and the bladder is pulled away from the slide.

Wheat germ agglutinin (WGA) reduces ADH-induced water flow and induces cell surface changes in epithelial cells of frog urinary bladder.

The functional and structural changes induced by apical wheat germ agglutinin (WGA) 100 micrograms/ml exposure on frog urinary bladder have been investigated and the possible correlations between these effects discussed. Bladders, apically exposed to WGA for 30 min to 3 hr exhibit a marked reduction of their response to antidiuretic hormone (ADH) challenge and of their hydrosmotic reactivity. Structural changes triggered by WGA treatment are: 1.

[Propentofylline and its analogs: a new class of agents for in vitro study of the antidiuretic response].

We took profit in this work of the discovery of a novel series of trialkylxanthines, with a biological activity greater than that of the other methylxanthines classically used as cAMP phosphodiesterase inhibitors. First, we determined their hydrosmotic activity, with the hope to find out compounds that could be used as apical agonists. Second, we employed these compounds as tools to further analyze the cellular mechanism of hydrosmotic response.

Three-dimensional graphical reconstruction from HVEM stereoviews of biological specimens by means of a microcomputer.

A microcomputer reconstruction technique has been developed in order to permit a larger exploitation of stereomicroscopy. The microcomputer facility consists of a digitizing tablet, a microcomputer, a graphics terminal, a graphics plotter and a printer. The technique has been applied to the study of HVEM stereopairs, performed by recording two images of the same area of a specimen (thick section of araldite-embedded leech ganglion neurons), tilted relative to the beam axis through an angle 0/20 degrees.

Effects of pentoxifylline and various methylxanthine derivatives on transepithelial water permeability of frog urinary bladder.

Theophylline, pentoxifylline and MIX (isobutyl methylxanthine) increase the water permeability of frog urinary bladder when added to the serosal side of the epithelium; this hydrosmotic effect is explained by an inhibition of adenylate cyclase. Both pentoxifylline and MIX exhibit an higher biological activity than theophylline. In contrast to theophylline, pentoxifylline and MIX stimulate the water permeability when added to the mucosal side of the epithelium; this probably results from a better penetration of these drugs into cells.