Responses of frog skin Na(+) and Cl(-) transport to guanylin.
A possible role for the peptide hormone guanylin was investigated in frog skin (Rana pipiens) epithelium. Sodium and chloride fluxes in response to this peptide were evaluated in Ussing-type chambers. Net and unidirectional Na(+) fluxes were measured by using (22)Na(+) and atomic absorption analysis of total [Na(+)], whereas net Cl(-) fluxes were measured by using electrometric titration for [Cl(-)]. Mucosal application of guanylin (0.5-2.0 micromol/l) caused marked increases in serosal to mucosal net flux and efflux of Na(+). Serosal application of guanylin over the same dose range caused similar large increases in net serosal to mucosal (S-->M) Na(+) and Cl(-) flux as well as Na(+) efflux. Responses of Na(+) influx were small and inconsistent. When frog skin was bathed on the serosal side with Cl(-)-free Ringer's solution mucosal application of guanylin stimulated large efflux and S-->M net fluxes of Na(+). Serosal treatment yielded large Na(+) effluxes and S-->M Na(+) and Cl(-) net fluxes. When frog skin serosal surfaces were bathed with Na(+)- free Ringer's solution mucosal guanylin treatment had no effect but serosal treatment produced large S-->M Cl(-) net fluxes.
Bernick
E P
EP
Biological Sciences Department, California State Polytechnic University, Pomona, CA 91768, USA.
Stiffler
D F
DF
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005768:Gastrointestinal Hormones; D045265:Natriuretic Peptides; D010455:Peptides / Q000494:pharmacology*; D011894:Rana pipiens / Q000502:physiology*; D012867:Skin / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism*
D002712:Chlorides; D005768:Gastrointestinal Hormones; D045265:Natriuretic Peptides; D010455:Peptides; C072685:guanylin; D012964:Sodium