X. Marechal et al., In vivo application of intestinal pH measurement using 2 ',7 '-bis(carboxyethyl)5,6-carboxyfluorescein (BCECF) fluorescence imaging, PHOTOCHEM P, 70(5), 1999, pp. 813-819
Measurement of gastrointestinal intramucosal pH (pH(im)) has been recognize
d as an important factor in the detection of hypoxia-induced dysfunctions.
However, current pH measurement techniques are limited in terms of time and
spatial resolutions. A major advance in accurate pH measurement was the de
velopment of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyet
hyl)-5,6-carboxyfluorescein (BCECF), This study aimed to set up and validat
e a fluorescence imaging technique to measure in vivo the intramucosal pH (
pH(im)) of the intestine. The intestine was inserted into an optical chambe
r placed under a microscope. Animals were injected intravenously with the p
H-sensitive fluorescent dye BCECF, Fluorescence was visualized by illuminat
ing the intestine alternately at 490 and 470 nm, The emitted fluorescence w
as directed to an intensified camera. The ratio of emitted fluorescence at
excitation wavelengths of 490 and 470 mm was measured, corrected and conver
ted to pH(im) by constructing a calibration curve. The pH(im) controls were
performed with a pH microelectrode and were correlated with venous blood g
as sampling. Results show that pH(im) is determined with an accuracy of +/-
0.07 pH units and a response time of 1 min. In conclusion pH(im) mapping of
rat intestine can be obtained by fluorescence imaging using BCECF, This te
chnology could be easily adapted for endoscopic pH measurements.