Stefan Postius

Evidence for a functional cytoprotective effect produced by antacids in the rat stomach

The fall in potential difference evoked by taurocholate was diminished after exposure of the gastric mucosa of rats to aluminium-containing antacids. Other parameters of barrier disruption (H+ back diffusion, Na+ influx) exhibited the same pattern and correlated with the change in potential difference. This cytoprotective-like effect was abolished in animals pretreated with indomethacin. Taurocholate significantly diminished the PGE2 content in the gastric mucosa and its release into the instillate. The PGE2 content of gastric mucosa and instillate of animals pretreated with an aluminium-containing antacid was not decreased after exposure to taurocholate.

In vivo rat bladder: A new model to screen spasmolytic compounds

A model for in vivo screening of spasmolytic compounds of the rat urinary bladder has been developed. It is physiological, specific, and adaptable. A filling volume of the bladder of 0.6-1 ml proved to be optimal. Agonists such as acetylcholine, KCl and BaCl2 exerted almost identical spasmogenic effects on both the in vivo and the in vitro model (isolated rat bladder strip). Moreover, the antagonistic effects of atropine, N-butylscopolammonium bromide, or flavoxate hydrochloride were directly comparable between the two models. Intravenously administered atropine was shown to be effective immediately; after intragastric application the maximum effect can not be observed until after 9 min. The in vivo rat bladder model presented is proposed to be a suitable method for advanced screening of spasmolytic compounds to include their absorption, biotransformation, and excretion.