{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T15:36:52Z","timestamp":1781105812277,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"17","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1983,9]]},"abstract":"<jats:p>The role of Ca2+ and calmodulin in regulating coupled NaCl transport has been investigated in membrane vesicles from rabbit ileal brush border. Uptake of 22Na+ and 36Cl- was determined by a rapid filtration technique in vesicles isolated with a sucrose density gradient ultracentrifugation method. Ca2+ on the inside of the vesicle inhibited Na+ uptake when Cl- was the anion and Cl- uptake when Na+ was the cation by approximately equal to 30%. Ca2+ on the outside had no effect. When gluconate was the anion or when choline was the cation, Na+ or Cl- uptake was reduced by only 9-12%. A similar inhibition of D-[3H]mannitol uptake (10-17%) suggests this was due to a nonspecific decrease in the membrane permeability. Other cations such as Ba2+ and Mg2+ had no effect, but La3+ inhibited Na+ and Cl- uptake to the same degree as Ca2+. Calmodulin (2 microM) in combination with Ca2+ (1 microM, free concentration) significantly inhibited Na+ uptake when Cl- was the anion by 21-32% and Cl- uptake when Na+ was the cation by 20-27%. This effect was completely reversed by 10 microM trifluoperazine. When gluconate was the anion or when choline was the cation, Na+ or Cl- uptake was unaffected by Ca2+\/calmodulin and trifluoperazine. The Ki for Ca2+ inhibition of Cl- -coupled Na+ uptake was reduced from 200 microM to 0.2 microM by incubation with 20 microM calmodulin. The Ki for exogenously added calmodulin studied at 1 microM Ca2+ was 0.2 microM. The Ki for trifluoperazine inhibition of the Ca2+\/calmodulin response was 3 microM. These results represent compelling evidence for intracellular Ca2+\/calmodulin regulation of coupled NaCl transport across the intestinal microvillus membrane. The exact mechanism of this regulation remains to be delineated.<\/jats:p>","DOI":"10.1073\/pnas.80.17.5248","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T05:11:59Z","timestamp":1149052319000},"page":"5248-5252","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":13,"title":["Calcium\/calmodulin inhibition of coupled NaCl transport in membrane vesicles from rabbit ileal brush border."],"prefix":"10.1073","volume":"80","author":[{"given":"C C","family":"Fan","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D W","family":"Powell","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1983,9]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.80.17.5248","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T11:56:53Z","timestamp":1649851013000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.80.17.5248"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1983,9]]},"references-count":0,"journal-issue":{"issue":"17","published-print":{"date-parts":[[1983,9]]}},"alternative-id":["10.1073\/pnas.80.17.5248"],"URL":"https:\/\/doi.org\/10.1073\/pnas.80.17.5248","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1983,9]]},"assertion":[{"value":"1983-09-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}