Effects of lubiprostone on human uterine smooth muscle cells

Lubiprostone, a bicyclic fatty acid derivative and member of a new class of compounds called prostones, locally activates ClC-2 Cl− channels without activation of prostaglandin receptors. The present study was specifically designed to test and compare lubiprostone and prostaglandin effects at the cellular level using human uterine smooth muscle cells. Effects on [Ca2+]i, membrane potential and [cAMP]i in human uterine smooth muscle cells were measured. 10 nM lubiprostone significantly decreased [Ca2+]i from 188 to 27 nM, which was unaffected by 100 nM SC-51322, a prostaglandin EP receptor antagonist. In contrast 10 nM PGE2 and PGE1 both increased [Ca2+]i 3–5-fold which was blocked by SC-51322. Similarly, lubiprostone and prostaglandins had opposite/different effects on membrane potential and [cAMP]i. Lubiprostone caused SC-51322-insensitive membrane hyperpolarization and no effect on [cAMP]i. PGE2 and PGE1 both caused SC-51322-sensitive membrane depolarization and increased [cAMP]i. Lubiprostone has fundamentally different cellular effects from prostaglandins that are not mediated by EP receptors.