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Acta Physiologica 2009; Volume 195, Supplement 667
XXXV Congress of The Spanish Society for Physiological Sciences
2/17/2009-2/20/2009
Valencia, Spain
A GENETICALLY ENCODED RATIOMETRIC SENSOR TO MEASURE EXTRACELLULAR PH IN MICRODOMAINS BOUNDED BY BASOLATERAL MEMBRANES OF EPITHELIAL CELLS
Abstract number: P94
Urra1 J, Sandoval1 M, Cornejo1 I, Barros1 LF, Sepulveda1 FV, Cid1 LP
1Centro de Estudios cientficos CECS, Valdivia Chile. [email protected]
Extracellular pH, especially in relatively inaccessible microdomains between cells, affects transport membrane protein activity and might have an intercellular signaling role.We have developed a genetically encoded extracellular pHsensor capable of detecting pH changes in basolateral spaces of epithelial cells. It consists of a chimerical lmembrane protein displaying concatenated enhanced variants of cyan fluorescence protein (ECFP) and yellow fluorescence protein (EYFP) at the external aspect of the cell surface. The construct, termed pHCECSensor01, was targeted to basolateral membranes of MadinDarby canine kidney (MDCK) cells by means of a sequence derived from the aquaporin AQP4. The fusion of pH-sensitive EYFP with pH-insensitive ECFP allows ratiometric pH measurements. The titration curve of pHCECSensor01 in vivo had a pKa value of 6.5 0.04. Only minor effects of extracellular chloride on pHCECSensor01 were observed around the physiological concentrations of this anion. In MDCK cells, the sensor was able to detect changes in pH secondary to H+ efflux into the basolateral spaces elicited by an ammonium prepulse or lactate load. This genetically encoded sensor has the potential to serve as a noninvasive tool for monitoring changes in extracellular pH microdomains in epithelial and other tissues in vivo.
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Acta Physiologica 2009; Volume 195, Supplement 667 :P94