Effects of LP-805, a novel vasorelaxant agent, a potassium channel opener, on rat thoracic aorta

Abstract 1. 1. In rat thoracic aorta, LP-805 (0.1–10 μM) caused the marked reduction of NE-induced maximum response and relaxed the low K + ( + (65.9 mM)-induced contraction. 2. 2. Glibenclamide (0.3–1 μM) caused a parallel shift of concentration-response curve produced by LP-805 for 25.9 mM K + -induced contraction and prevented the LP-805-induced reduction in maximum response evoked by NE in a concentration-dependent manner. 3. 3. Glibenclamide (10 μM) prevented the LP-805 (10 μM)-induced decrease in cytosolic Ca 2+ levels which was increased by 1 μM NE or 25.9 mM K + . 4. 4. LP-805 (10 μM) increased basal 86 Rb efflux, which was completely inhibited by 10 μM glibenclamide. 5. 5. These results suggest that LP-805 causes a vasorelaxation as a consequence of the decrease in cytosolic Ca 2+ levels due to the increase in K + efflux via opening ATP-dependent K + channels.