Premium
CONTINUOUS, NONINVASIVE MEASUREMENT OF In Vivo pH IN CONSCIOUS MICE
Author(s) -
Russell David A.,
Pottier Roy H.,
Valenzeno Dennis P.
Publication year - 1994
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1994.tb05039.x
Subject(s) - fluorescence , chemistry , hairless , in vivo , extracellular , biophysics , analytical chemistry (journal) , aqueous solution , photomultiplier , chromatography , biochemistry , optics , biology , physics , microbiology and biotechnology , detector
Extracellular pH was measured continuously and noninvasively in hairless mice using a transcutaneous spectronuorometric technique and a fluorescent pH probe, bis ‐carboxyethyl carboxyfluorescein (BCECF). The acid form of BCECF was injected intravenously. An optical fiber system excited the florescent probe at 450 and 500 nm alternately, using one branch of a bifurcated, fiber optic bundle. The other branch of the bundle collected the emitted fluorescence which was measured by a photomultiplier tube. The ratio of fluorescence intensities from the two excitation wavelengths was pH dependent. Measurements could be obtained for approximately 60 min following a single injection. Mice exposed to elevated partial pressures of CO 2 demonstrated changes in the fluorescence ratio indicative of a dramatic decrease in extracellular pH. If the exposure was brief, the fluorescence signal recovered within 20 min. The fluorescence intensity ratio was calibrated against aqueous BCECF samples in vitro. Fluorescence pH values determined using the in vitro calibration were compared with measurements made on blood samples taken from seven mice. Extracellular pH in hairless mice was found to be approximately 7.5, within the expected physiological range. The variability of the pH signal derived from the fluorescence signal was approximately 0.05 units.