Prostanoid EP3 receptor agonist sulprostone enhances pacemaker activity of colonic interstitial cells of Cajal.

EP receptor activation by PGE2 regulates gastrointestinal motility by modulating smooth muscle contractility. Interstitial cells of Cajal (ICCs) are pacemaker cells that regulate smooth muscle activity. We aimed to determine effects of the EP3 receptor agonist sulprostone on pacemaker potentials in colonic ICCs. We performed a whole cell patch clamp, RT-PCR, and Ca2+ imaging in cultured ICCs from mouse colon. Sulprostone depolarized the membrane and increased pacemaker frequency. EP3 receptor antagonist blocked these sulprostone-induced effects. EP3 receptors were expressed in ANO1-positive ICCs. Phospholipase C inhibitor or Ca2+-ATPase inhibitor from the endoplasmic reticulum blocked the sulprostone-induced effects and sulprostone increased intracellular Ca2+ ([Ca2+]i) oscillations. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blockers also suppressed the sulprostone-induced effects. Sulprostone enhanced pacemaker activity through EP3 receptors by activating HCN channels via the [Ca2+]i release pathway. Therefore, EP3 receptor activation in ICCs may modulate colonic motility and could be a therapeutic target for enhancing colonic GI motility.