Isoprenaline-induced desensitization in vitro in rat trachea was studi
ed in the presence of the Ca2+-channel blockers (Ca2+-CBs) verapamil a
nd nitrendipine. The concentration-response curves for isoprenaline we
re determined in a noncumulative manner using carbachol as contracting
agent, and then desensitization was achieved by 40-min incubation of
the tracheal preparations with isoprenaline (1 mu M). The effect of ve
rapamil and nitrendipine was studied by the addition of each Ca2+-CB t
o the desensitizing solution. Both verapamil and nitrendipine reduced
the isoprenaline-induced desensitization in the rat trachea. (C) 1997
Elsevier Science Inc.