Inhibitory Mechanism of Monensin on High K+-Induced Contraction in Guniea-Pig Urinary Bladder

[摘要] References(36)Cited-By(2)In this study, we examined the inhibitory mechanism of monensin on high K+-induced contraction in guinea-pig urinary bladder. The relaxant effect of monensin (0.001 – 10 μM) was more potent than those of NaCN (100 μM – 1 mM) and forskolin (3 – 10 μM). Monensin (0.1 μM), NaCN (300 μM), or forskolin (10 μM) inhibited high K+-induced contraction without decreasing [Ca2+]i level. Monensin and NaCN remarkably decreased creatine phosphate and ATP contents. Monensin and NaCN inhibited high K+-induced increases in flavoprotein fluorescence, which is involved in mitochondrial respiration. Forskolin increased cAMP content but monensin did not. Monensin increased Na+ content at 10 μM but not at 0.1 μM that induced maximum relaxation. In the α-toxin-permeabilized muscle, forskolin significantly inhibited the Ca2+-induced contraction, but monensin did not affect it. These results suggest that the relaxation mechanism of monensin in smooth muscle of urinary bladder may be an inhibition of oxidative metabolism.

[学科分类] 药学

[关键词] monensin;urinary bladder;phosphocreatine;Na+ content