{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,21]],"date-time":"2025-10-21T03:26:54Z","timestamp":1761017214849},"reference-count":0,"publisher":"American Physiological Society","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Gastrointestinal and Liver Physiology"],"published-print":{"date-parts":[[1988,10,1]]},"abstract":"<jats:p> The present studies investigated the mechanism of Ca2+ transport across basolateral membrane vesicles (BLMVs) prepared from human small intestine. Ca2+ uptake represented transport into the intravesicular space as evident by osmolality study and by the demonstration of Ca2+ efflux from the intravesicular space by Ca2+ ionophore A23187. Ca2+ uptake was stimulated by Mg2+-ATP. Kinetic parameters for ATP-dependent Ca2+ uptake revealed a Michaelis constant (Km) of 0.02 +\/- 0.01 microM and a maximum rate of uptake (Vmax) of 1.00 +\/- 0.03 nmol.mg protein-1.min-1.Ca2+ uptake in the absence of Mg2+ was inhibited by 75%. The Km of ATP concentration required for half-maximal Ca2+ uptake was 0.50 +\/- 0.1 mM. Calmodulin (10 micrograms\/ml) increased Vmax to 1.62 +\/- 0.02 nmol.mg protein-1.min-1 (P less than 0.001). Km values were 0.017 +\/- 0.001 microM, which was not significantly different from control values. Basolateral membranes depleted of calmodulin by EDTA osmotic shock decreased ATP-dependent Ca2+ uptake by 65%. Trifluoperazine, an anticalmodulin drug, inhibited ATP-dependent Ca2+ uptake by 50%, while no inhibition was noted in calmodulin-depleted membranes. Efflux of Ca2+ in the BLMVs was stimulated by trans-Na+. Na+-dependent Ca2+ uptake was saturable with respect to Ca2+ concentration and exhibited a Km of 0.09 +\/- 0.03 microM and a Vmax of 1.08 +\/- 0.01 nmol.mg protein-1.min-1. These results are consistent with the existence of a Na+-Ca2+ exchange system and ATP and Mg2+-dependent, calmodulin-regulated Ca2+, transport mechanism in BLMVs of human enterocytes. <\/jats:p>","DOI":"10.1152\/ajpgi.1988.255.4.g482","type":"journal-article","created":{"date-parts":[[2017,12,24]],"date-time":"2017-12-24T06:35:17Z","timestamp":1514097317000},"page":"G482-G489","source":"Crossref","is-referenced-by-count":2,"title":["Characterization of calcium transport by basolateral membrane vesicles of human small intestine"],"prefix":"10.1152","volume":"255","author":[{"given":"K.","family":"Kikuchi","sequence":"first","affiliation":[{"name":"Department of Pediatrics, Vanderbilt University School of Medicine,Nashville, Tennessee 37232."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T.","family":"Kikuchi","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Vanderbilt University School of Medicine,Nashville, Tennessee 37232."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"F. K.","family":"Ghishan","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Vanderbilt University School of Medicine,Nashville, Tennessee 37232."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"24","container-title":["American Journal of Physiology-Gastrointestinal and Liver Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/ajpgi.1988.255.4.G482","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,8]],"date-time":"2019-09-08T23:18:03Z","timestamp":1567984683000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/ajpgi.1988.255.4.G482"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1988,10,1]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[1988,10,1]]}},"alternative-id":["10.1152\/ajpgi.1988.255.4.G482"],"URL":"https:\/\/doi.org\/10.1152\/ajpgi.1988.255.4.g482","relation":{},"ISSN":["0193-1857","1522-1547"],"issn-type":[{"value":"0193-1857","type":"print"},{"value":"1522-1547","type":"electronic"}],"subject":[],"published":{"date-parts":[[1988,10,1]]}}}