Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon

Abstract

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1-3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1-3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1-3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P Ͻ 0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles. gastrointestinal tract; mucosal chloride secretion; enteric nervous system; prostaglandins; irritable bowel syndrome; cystic fibrosis transmembrane conductance regulator; ClC-2 channels LUBIPROSTONE IS CLASSIFIED as a prostone. Prostones are compounds derived from naturally occurring fatty acids associated with cell membranes. Lubiprostone is a bicyclic fatty acid, which is derived from a metabolite of prostaglandin E1 (PGE 1 ) (36). The available evidence suggests that it acts directly to open and increase Cl Ϫ conductance in ClC-2 channels, which are expressed in the apical membranes of mucosal epithelial cells in the intestinal tract and epithelia elsewhere in the body.Application of lubiprostone to confluent T84 cell monolayers stimulates, in a concentration-dependent manner, electrogenic Cl Ϫ secretion, which can be measured as increased short-circuit current (I sc ) across the monolayer (16). Lubiprostone also activates ClC-2 channel currents in whole cell patch-clamp studies in human embryonic kidney (HEK)-293 cells that are stably transfected with recombinant human ClC-2 channels (16). Stimulation of I sc across confluent T84 cell monolayers occurs with an EC 50 of 18 ...

Lubiprostone Reverses the Inhibitory Action of Morphine on Intestinal Secretion in Guinea Pig and Mouse

“…The mechanism of lubiprostone action is thought to be opening of chloride (Cl Ϫ ) channels in the small and large intestinal epithelium (Fei et al, 2009) and bicarbonate (HCO 3 Ϫ ) secretory pathways in the duodenum (Mizumori et al, 2009). Even so, clear-cut identification of the Cl Ϫ channels through which lubiprostone stimulates intestinal Cl Ϫ secretion is unresolved.…”

“…Exposure of flat-sheet preparations from guinea pig small or large intestinal preparations in Ussing flux chambers to lubiprostone stimulates chloride secretion, with a low EC 50 value of 43.5 nM in the small intestine and an EC 50 value of 31.7 nM in the colon (Fei et al, 2009). Lubiprostone stimulates chloride secretion, with an EC 50 value of 24.3 nM across flat-sheet preparations of human jejunum in Ussing chambers (Sun et al, 2008).…”

“…The selective CFTR channel blocker CFTR(inh)-172 does not suppress lubiprostone stimulation of chloride secretion (Fei et al, 2009). In contrast, Bijvelds et al (2009) reported that stimulation by lubiprostone of chloride movement across T84 cell monolayers was blocked by CFTR(inh)-172, which supported action at CFTR rather than ClC-2.…”

GRG Profiles: Jackie D. Wood

“…Translational significance of these discoveries are firstly, any condition that elevates excitability of secretomotor neurons leads to a diarrheal state (e.g., infectious diarrhea), and second, conditions in which excitability of secretomotor neurons is suppressed lead to constipation (e.g., opioid-induced constipation). Our data on neurogenic secretion are published in 20 peer-reviewed journals [28][29][30][31][32].…”

Neurophysiological mechanisms of bradykinin-evoked mucosal chloride secretion in guinea pig small intestine

“…Adult male Hartleystrain guinea pigs (300-350 g) were stunned by a sharp blow to the head and exsanguinated from the cervical vessels according to a protocol approved by Weifang Medical University Laboratory Animal Care and Use Committee. The tissue preparations were essentially conducted as described [13,14] . Briefly, segments of the small intestine were removed, flushed with ice-cold Krebs solution, and opened along the mesenteric border.…”