EFFECT OF ARACHIDONIC-ACID ON HISTAMINE-INDUCED AND METHACHOLINE-INDUCED CONTRACTION OF THE ISOLATED GUINEA-PIG TRACHEAL CHAIN WITH AND WITHOUT EPITHELIAL-CELLS
Cp. Kahler et Wj. Duplooy, EFFECT OF ARACHIDONIC-ACID ON HISTAMINE-INDUCED AND METHACHOLINE-INDUCED CONTRACTION OF THE ISOLATED GUINEA-PIG TRACHEAL CHAIN WITH AND WITHOUT EPITHELIAL-CELLS, Medical science research, 24(6), 1996, pp. 407-410
The relaxant effect of exogenous arachidonic acid on histamine- and me
thacholine-induced contraction was investigated and also the contribut
ion of the epithelium and the role of synthesised prostaglandins by th
e epithelium. The isolated tracheas of six guinea-pigs were used in ea
ch experiment and suspended in organ baths filled with Krebs-Henseleit
solution and gassed with 95% O-2 and 5% CO2. Arachidonic acid produce
d a relaxation of 43.5 +/- 3.2% (3 x 10(-4) M) (p < 0.05) for methacho
line-induced contraction and 60.7 +/- 0.2% (10(-5) M) (p < 0.05) for h
istamine-induced contraction as compared to salbutamol in preparations
with intact epithelium. Epithelium removal had opposite effects for t
he different contractants. The relaxant effect of arachidonic acid aft
er methacholine-induced contraction was increased, but the relaxant ef
fect of arachidonic acid after histamine-induced contraction was decre
ased. Indomethacin pre-incubation had no effect on the relaxant effect
of arachidonic acid after methacholine-induced contraction, but the r
elaxant effect of arachidonic acid was changed to contraction after hi
stamine-induced contraction at concentrations of 10(-5) M and higher o
f arachidonic acid. This occurred in preparations with intact epitheli
um and with no epithelium. It is clear that the mechanism involved in
the relaxant effect of arachidonic acid is complex and involves the pr
oducts produced by the epithelial cells and the added effects induced
by the specific contractant used.