Quantitative confocal imaging along the crypt-to-surface axis of
colonic crypts.
Chu, Shaoyou, William E. Brownell, and Marshall H. Montrose.
Division of Gastroenterology, Departments of Medicine and
Physiology, Johns Hopkins University School of Medicine, Baltimore,
Maryland 21205; and Department of Otorhinolaryngology and
Communicative Sciences, Baylor College of Medicine, Houston,
Texas
APStracts 2:0254C, 1995.
Quantitative confocal microscopy methods are used to measure events
along the crypt-to-surface axis in living mouse colonic mucosa.
Experiments visualize carboxy SNARF-1 (a pH-sensitive fluorescent
dye) in the extracellular fluid, to measure extracellular pH within
an intact epithelium. Lucifer Yellow (LY) (a pH-insensitive dye) is
used to control for fidelity of the optical path. Light scatter from
colonic tissue caused SNARF-1 or LY fluorescence to decrease 3% per
micrometer focal distance into tissue, at both 640nm and 580nm
emission wavelengths. However, dual emission ratios of LY
fluorescence were constant as a function of focal distance into
tissue, or in the presence of short-chain fatty acids (SCFAs). SCFAs,
known to cause changes in extracellular pH, cause maximal changes in
crypt luminal pH at 10[mu]m from the crypt base. Maximal changes of
pH in lamina propria occur higher along the crypt-to-surface axis
than maximal changes in luminal pH. Lateral intercellular spaces
between colonocytes are a separate microdomain in which pH is
constant in absence versus presence of SCFAs, and constant along the
base-to-apex axis of colonocytes.
Received 3 April 1995; accepted in final form 9 June 1995
APS Manuscript Number C0184-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.