期刊
AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY
卷 284, 期 1, 页码 F122-F132出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajprenal.00161.2002
关键词
calcium transport; kidney distal tubules; Madin-Darby canine kidney; sodium/calcium exchanger; plasma membrane calcium ATPase
资金
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM058710] Funding Source: NIH RePORTER
- NIGMS NIH HHS [GM-58710] Funding Source: Medline
Plasma membrane Ca2+ ATPases (PMCAs) are ubiquitous in Ca2+-transporting organs, including the kidney. Using RT-PCR, we detected PMCA1b, PMCA2b (rare), and PMCA4b in Madin-Darby canine kidney (MDCK) cells. At the protein level, only PMCA1 and PMCA4 were readily detected and were highly enriched in the basolateral membrane. The Na+/Ca2+ exchanger NCX1 was also detected at the transcript and protein level. A functional assay measuring Ca-45(2+) flux across MDCK cell monolayers under resting conditions indicated that two-thirds of apicobasolateral Ca2+ transport was provided by Na+/Ca2+ exchanger and one-third by PMCAs, as determined in Na+-free media and using various PMCA inhibitors (La3+, vanadate, calmidazolium, and trifluoroperazine). The importance of PMCA4b for basolateral Ca2+ efflux was demonstrated by overexpression of PMCA4b or antisense knockdown of endogenous PMCA4b. Overexpression of PMCA4b increased apicobasolateral Ca2+ transport to similar to140%, whereas antisense treatment reduced Ca2+ flux similar to45% compared with controls. The MDCK system is thus an ideal model for functional studies of the specific role and regulation of PMCA isoforms in Ca2+ reabsorption in the distal kidney.
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