Abstract
Electrogenic ion transport across the epithelium lining the descending colon of male Sprague-Dawley rats has been measured under short-circuit conditions. Responses to kallidin (lysylbradykinin) were inhibited by 70% if calcium was removed from the solution bathing the basolateral aspect of the tissue. Under identical conditions responses to prostaglandin E1 and dibutyryl cyclic adenosine monophosphate were not changed. Forskolin, which directly activates the catalytic subunit of adenylate cyclase, was inhibited by 35% by calcium removal, whereas responses to the phosphodiesterase inhibitor isobutylmethylxanthine were inhibited by 45% by the same procedure. In the absence of calcium, strontium could substitute in promoting the chloride secretory events triggered by kallidin. Magnesium ions antagonized the effects of the kinin in the presence of calcium ions in the bathing solution. The effects of kallidin were partially antagonized by verapamil and trifluoperazine and were potentiated by isobutylmethylxanthine. These results, together with earlier evidence, suggest that kinin elicits a chloride secretory response in this epithelium by stimulating the formation of prostaglandins which then activate adenylate cyclase. Extracellular calcium ions appear to have an important role in the proximal part of this cascade for prostaglandin generation. However, biochemical correlates of these biophysical responses presented in the following paper indicate a more complex role for calcium in the genesis of the kinin response.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.