Acetylcholine in isolated airways of rat, guinea-pig and man;
species differences in the role of the airway mucosa.
Reinheimer, T., P. Bernedo, H. Klapproth, H. Oelert, B. Zeiske, K.
Rack[acute]e, and I. Wessler.
Pharmakologisches Institut der Universit[umlaut]at Mainz und Klinik
f[umlaut]ur Herz-, Thorax- und Gef[umlaut]a[beta]chirurgie, Obere
Zahlbacher Stra[beta]e 67, D-55101 Mainz, Germany, Institut
f[umlaut]ur Pharmakologie und Toxikologie, Universit[umlaut]at Bonn,
Reuterstr. 2b, D-53113 Bonn, Germany
APStracts 2:0209L, 1995.
Stored, endogenous acetylcholine and in vitro-synthesis of
[3H]acetylcholine were measured in isolated, mucosa-intact and
mucosa-denuded airways of rat, guinea-pig and man. In addition,
choline acetyltransferase (ChAT) activity and acetylcholine content
were measured in freshly isolated airway mucosa as well as in
cultured epithelial cells of rat tracheae. Rat tracheae stored 25
nmol/g acetylcholine, whereas guinea-pig tracheae and human bronchi
contained only 2 - 3 nmol/g acetylcholine. When incubated with
[3H]choline the isolated airways of rat, guinea-pig and man
synthesized significant amounts of [3H]acetylcholine. In guinea-pig
and human airways removal of the mucosa affected neither stored
acetylcholine nor in vitro-synthesis of [3H]acetylcholine. However,
in rat tracheae removal of the mucosa resulted in a 50% reduction of
stored acetylcholine. Freshly isolated mucosa wiped off from the
luminal surface of rat tracheae contained large amounts of
acetylcholine (6.5 nmol per g airway), whereas in human mucosa
(central bronchi) only small amounts of acetylcholine were found. In
enzymatically-isolated mucosal cells of rat tracheae a considerably
ChAT activity (21 nmol/mg protein/h) was detected, blockable by
bromoacetylcholine. Enzymatically-isolated human mucosa contained a
rather low ChAT-like activity (0.5 nmol/mg protein/h), not sensitive
to bromoacetylcholine. In cultured epithelial cells of rat tracheae
(4th - 6th passage) neither ChAT activity nor acetylcholine was
detected.
Received 1 August 1995; accepted in final form 6 November 1995.
APS Manuscript Number L238-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95