EFFECT OF CA2-CHANNEL BLOCKERS ON ISOPRENALINE-INDUCED DESENSITIZATION IN RAT TRACHEA()

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.