Contractile effects and intracellular Ca²⁺signalling induced by emodin in circular smooth muscle cells of rat colon

Abstract

Emodin has a direct excitatory effect on circular smooth muscle cells in rat colon mediated via Ca(2+)/CaM dependent pathways. Furthermore, emodin-induced peak [Ca(2+)]i increase may be attributable to the Ca(2+) release from IP(3) sensitive stores, which further promote Ca(2+) release from ryanodine-sensitive stores through CICR mechanism. Additionally, Ca(2+) influx from extracellular medium contributes to the sustained increase in [Ca(2+)]i.

Effects of Emodin on Ca2+ Signal Transduction of Smooth Muscle Cells in Multiple Organ Dysfunction Syndrome

“…Ma had proved that exposure of smooth muscle cells to emodin induced an increase in [Ca 2ϩ ]i, and the resultant rising in [Ca 2ϩ ]i was a biphasic rise in [Ca 2ϩ ] consisting of a rapid, transient peak followed by a decline to sustained level that remained elevated above baseline [11]. It is considered the main mechanism for emodin to elevate Ca 2ϩ in SMCs in the physiological conditions via IP 3 route.…”

“…The contractions of SMCs of the colon were measured using computerized image micrometry as described previously [11]. Briefly, the cell suspensions of 0.25-ml consisting of 1 ϫ 10 4 cells were added to 0.1 ml of the solutions containing the test agents.…”

“…Furthermore, emodin-induced peak [Ca 2ϩ ]i increase may be attributable to the Ca 2ϩ release from IP3 sensitive stores, which further promote Ca 2ϩ release from ryanodine-sensitive stores through CICR mechanism. Additionally, Ca 2ϩ influx from extracellular medium contributes to the sustained increase in [Ca 2ϩ ]i [11].…”

Roles of calcium and IP3 in impaired colon contractility of rats following multiple organ dysfunction syndrome

“…The contractile response after each agent was defined as the decrease in the average length of the 50 cells and expressed as a percentage of the length before agent administration (17,18).…”

Emodin Inhibits Voltage‐Dependent Potassium Current in Guinea Pig Gallbladder Smooth Muscle

“…First, it has been shown that emodin enhanced the function of small intestinal peristalsis through triggering the release of motilin and Ach and inhibiting the secretion of somatostatin [3,4]. Secondly, emodin directly contracts the colon smooth muscle by elevating the intracellular Ca 2+ concentration, through Ca 2+ influx from extracellular medium and Ca 2+ release from intracellular stores [5,6]. Furthermore, it has been reported that emodin enhanced colon peristalsis by inhibiting voltagedependent K + current [2].…”