Mebeverine influences sodium ion transport in the distal colon.

The study was performed to check if the well-known intestinal spasmolytic effect of mebeverine is paralleled by any changes in intestinal transepithelial currents. The transepithelial potential difference related to ionic currents of the isolated rabbit distal colon wall was measured by means of Ussing's technique under control conditions and after gentle mechanical stimulation of intestinal epithelial surface by a flux from peristaltic pump and with and without of mebeverine in stimulation fluid. The transient hyperpolarization after mechanical stimulation was diminished after addition of mebeverine to the stimulation fluid when chloride transport was inhibited by bumetanide (BUME) but in the presence of amiloride (AMI), a sodium ion transport inhibitor, the drug did not influence the reaction. It was inferred that mebeverine was able to modulate transepithelial sodium ion transport and in this way to modify interaction between colonic wall and its contents during intestinal passage.

Effects of amiloride and bumetanide on hyperpolarization after movement across the distal colon epithelium.

The aim of the paper was to define which transepithelial ion transport pathways were activated during stimulation by movement across the colonic epithelium. The experiments were performed with Ussing method on 241 specimens of isolated distal colon wall from 51 rabbits. The tissue was stimulated by a flux from peristaltic pump which caused transient hyperpolarization of the isolated tissue. In the control, the transepithelial potential difference (PD) and its changes during stimulation (dPD) were -3.16 +/- 1.81 mV and -2.16 +/- 0.99 mV, respectively. Preincubation of the tissue in the presence of amiloride diminished the PD and dPD by about 50% and 64%, respectively, and in the presence of bumetanide, both PD and dPD were lower by about 30%. The separate application either of inhibitors only to the stimulation fluid usually diminished the hyperpolarization. The combined inhibition of adrenergic (benextramine and timolol) and cholinergic (atropine and hexamethonium) transmission did not influence the hyperpolarization. It is summarized that hyperpolarization depends on electrogenic sodium currents in the presence of bumetanide or electrogenic chloride currents in the presence of amiloride. After simultaneous application of both inhibitors, small but significant hyperpolarization reaction occurred which was caused by yet unidentified ionic currents. Participation of the sodium and/or chloride ions in physiologically (without inhibitors) evoked hyperpolarization is variable and the two mutually excluding situations, when only one ion transport is responsible for the whole reaction, are extremes of the range of possibilities. Usually, both these ion currents participate in the hyperpolarization reaction.

Effects of halothane and isoflurane on stimulated airway transepithelial ion transport.

Volatile anesthetics are suggested to elicit depression of airway clearance. The involvement of changes in transepithelial ion transport in this inhibition has already been observed. The Ussing method was used to study the changes in mechanical stimulation evoked electrogenic ion transport in isolated rabbit tracheal wall in the presence of halothane and isoflurane. The drugs dissolved in Ringer solution were directed as a flux from peristaltic pump to mucosal surface of trachea. In experimental settings without or with amiloride, the anestethics elicited reversible inhibition of stimulated ion transport and depolarization of transepithelial potential difference. Participation of chloride ion transport in observed changes is suggested. In the light of this study with application of anesthetics at higher concentrations than clinically relevant, the possibility of disturbances of airway transepithelial ion transport by clinically relevant concentration should be checked.

Effect of amiloride and bumetanide on transepithelial ion transport in isolated rabbit cecal and colonic wall.

INTRODUCTION: The aim of the study was to compare the effects of amiloride and bumetanide on the baseline transepithelial electrical potential difference (PD) and changes in PD during mechanical stimulation (dPD) in isolated cecal and colonic wall of rabbits. MATERIAL/METHODS: The experiments were performed with a modified Ussing chamber system. Isolated tissue specimens were incubated in Ringer's solution, in amiloride and/or bumetanide, or in dimethyl sulfoxide (DMSO). RESULTS: Under control conditions, i.e. when all the experimental fluids were Ringer's solution, the PD and R values of the rabbit cecum and colon were similar, while during mechanical stimulation, dPD of the colon was twice as high as that of the cecum. Addition of amiloride and/or bumetanide to all experimental fluids diminished the electrophysiological parameters of both tissues. DMSO added to all experimental fluids significantly diminished the values of the electrophysiological parameters of the cecum. Addition of amiloride to the stimulation fluid only diminished the PD and dPD values in the colon, whereas addition of bumetanide to the stimulation fluid only diminished the PD and dPD values in the cecum. It was found that the PD and dPD values of the rabbit cecum depend primarily on chloride ion transport, while those of the colon depend on sodium ion transport.

The influence of ambroxol and capsaicin on the isolated rabbit bladder wall.

Unmyelinated C-fibers endings lye beneath the epithelial layer and release neuropeptides which regulate baseline transepithelial potential difference (PD) and changes of transepithelial potential difference during mechanical stimulation (dPD). Ambroxol can suppress reflexes such as the cough or the corneal reflex which are connected to stimulation of C fibre endings. The study aimed to estimate the influence of ambroxol (ABX) and capsaicin (CAPSA) on PD and dPD in isolated rabbit bladder. The experiments were carried out on 26 bladder specimens of. 2 cm2 surface area each, obtained from 13 rabbits. Ussing apparatus was used. Procedure used for stimulation of sensory receptor involved directing stream onto epithelium. A stimulus lasted 30s, ejecting the 2.5 ml fluid. Amiloride and bumetanide were used to estimate of ionic currents. Each significant reaction was repeated at least 10 times on various specimens. PD ranged between 5 and 10 mV in different experimental conditions. Mechanical stimulation of isolated bladder wall caused increasing dPD about 2 mV defined as hyperpolarization. Application of ABX to the stimulation fluid decreased the hyperpolarization in comparison with control stimulation under conditions of inhibited chloride ion transport. Application of CAPSA to the stimulation fluid decreased the hyperpolarization in comparison with control stimulation under conditions of inhibited sodium ion transport. ABX and CAPSA had no influence on PD after mechanical stimulation. ABX as well as CAPSA influence on transepithelial ion transport pathways in bladder epithelium is dependent on sensory stimulation. ABX can be suspected to suppress bladder contractions.