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BRAIN pH MEASUREMENTS USING A DIFFUSIBLE, LIPID SOLUBLE pH SENSITIVE FLUORESCENT INDICATOR
Author(s) -
Sundt Thoralf M.,
Anderson Robert E.,
Dyke Russell A.
Publication year - 1978
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1978.tb07834.x
Subject(s) - normocapnia , chemistry , ph indicator , intracellular ph , fluorescence , hypocapnia , in vivo , chromatography , brain tissue , biophysics , biochemistry , hypercapnia , acidosis , intracellular , anatomy , endocrinology , biology , physics , microbiology and biotechnology , quantum mechanics
— Brain tissue pH was measured in cats at normocapnia hypocapnia, hypercapnia, and death from anoxia using a pH sensitive fluorescent indicator (umbelliferone) with both molecular and ionic fluorophors. A ratio analysis of the indicator's calibrated 450 nm fluorescent tissue washout curves from 340 and 370 nm excitation permitted direct determinations using a nomogram. Possible errors in these measurements related to differential quenching, absorption, and changes in the redox state of the indicator were investigated in vitro and in vivo for brain tissue and blood. In animals with preserved autoregulation, brain pH varied linearly with arterial pH (art pH 7.0, brain pH 6.98: art pH 7.4, brain pH 7.24). Brain pH at death fell to 6.68. An analysis of the indicator clearance curves suggests these measurements reflect a component of the intracellular space and the lipid solubility of the indicator suggests this is a membranous component.