The effects of cetiedil and its congeners on levcromakalim-stimulated 86Rb efflux from smooth and skeletal muscle.

The effects of cetiedil on levcromakalim-stimulated 86Rb efflux from rat aorta, rat anococcygeus and frog sartorius muscle have been investigated. In experiments on rat aorta, cetiedil inhibited the tracer efflux stimulated by 10 microM levcromakalim with an IC50 of 1.3 +/- 0.4 microM. In the rat anococcygeus and frog sartorius 10 microM cetiedil caused 67 +/- 11% and 84 +/- 4% inhibition of the responses to 10 microM and 50 microM levcromakalim respectively. The effect of two analogues of cetiedil, UCL 1285 (cetiedil methiodide) and UCL 1495 (triphenyl acetic acid-2-N[5-ethyl-2-methylpiperidinoethyl] ester) were also tested on rat aorta. UCL 1285 caused inhibition of the response to 10 microM levcromakalim with an IC50 of approximately 6 microM. In contrast, UCL 1495 (10 microM) had no significant effect. It is concluded that cetiedil is an effective blocker of the action of levcromakalim in smooth and skeletal muscle but does not distinguish between tissues. The relative activities of cetiedil, UCL 1285 and UCL 1495 are discussed in relation to their activity at other cetiedil-sensitive K+ channels.