Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated guinea pig colon

Repositioning Trimebutine Maleate as a Cancer Treatment Targeting Ovarian Cancer Stem Cells

The overall five-year survival rate for late-stage patients of ovarian cancer is below 29% due to disease recurrence and drug resistance. Cancer stem cells (CSCs) are known as a major contributor to drug resistance and recurrence. Accordingly, therapies targeting ovarian CSCs are needed to overcome the limitations of present treatments. This study evaluated the effect of trimebutine maleate (TM) targeting ovarian CSCs, using A2780-SP cells acquired by a sphere culture of A2780 epithelial ovarian cancer cells. TM is indicated as a gastrointestinal motility modulator and is known to as a peripheral opioid receptor agonist and a blocker for various channels. The GI50 of TM was approximately 0.4 µM in A2780-SP cells but over 100 µM in A2780 cells, demonstrating CSCs specific growth inhibition. TM induced G0/G1 arrest and increased the AV⁺/PI⁺ dead cell population in the A2780-SP samples. Furthermore, TM treatment significantly reduced tumor growth in A2780-SP xenograft mice. Voltage gated calcium channels (VGCC) and calcium-activated potassium channels (BKCa) were overexpressed on ovarian CSCs and targeted by TM; inhibition of both channels reduced A2780-SP cells viability. TM reduced stemness-related protein expression; this tendency was reproduced by the simultaneous inhibition of VGCC and BKCa compared to single channel inhibition. In addition, TM suppressed the Wnt/β-catenin, Notch, and Hedgehog pathways which contribute to many CSCs characteristics. Specifically, further suppression of the Wnt/β-catenin pathway by simultaneous inhibition of BKCa and VGCC is necessary for the effective and selective action of TM. Taken together, TM is a potential therapeutic drug for preventing ovarian cancer recurrence and drug resistance.

Effects of trimebutine maleate on colonic motility through Ca²+-activated K+ channels and L-type Ca²+ channels

The effects of trimebutine maleate (TM) on spontaneous contractions of colonic longitudinal muscle were investigated in guinea pigs. The contractile responses of smooth muscle strips were recorded by an isometric force transducer. Membrane and action potentials were detected by an intracellular microelectrode technique. The whole-cell patch clamp recording technique was used to record the changes in large conductance Ca(2+)-activated K(+) (BK(ca)) and L-type Ca(2+) currents in colonic smooth muscle cells. At high concentrations (30, 100, and 300 μM), TM inhibited the amplitude of spontaneous contractions. At low concentrations (1 and 10 μM), TM attenuated the frequency and tone of smooth muscle strips, whereas TM had no influence on the amplitude of spontaneous contractions. TM depolarized the membrane potentials, but decreased the amplitude and frequency of action potentials at high concentrations. TM inhibited BK(ca) and L-type Ca(2+) currents in a dose-dependent manner. In the presence of the BK(ca) channel opener, NS1619, TM also inhibited BK(ca) currents. Bayk8644, a L-type Ca(2+) channel opener, increased L-type Ca(2+) currents. This augmentation was also attenuated by TM. These results suggest that TM attenuates intestinal motility through inhibition of L-type Ca(2+) currents, and depolarizes membrane potentials by reducing BK(ca) currents. Thus, TM may be a multiple-ion channel regulator in the gastrointestinal tract.

Determination of trimebutine maleate in rat plasma and tissues by using capillary zone electrophoresis

A simple and rapid capillary zone electrophoresis method was developed for the determination of trimebutine maleate in rat plasma and tissues. Rat plasma and tissue homogenates were mixed with acetonitrile containing internal standard, ephedrine hydrochloride, and then centrifuged. The supernatant was dried under a stream of nitrogen, and the residue was reconstituted in methanol-water (1:1). The electrophoresis was performed in uncoated capillary with 30 mmol/L phosphate buffer of pH 6.0 as the separation electrolyte. The applied voltage was 10 kV and the UV detection was set at 214 nm. The peak height ratio vs concentration in plasma or homogenates was linear over the range of 5-500 ng/mL and the limit of quantitation was 5 ng/mL. The intra- and inter-day precision was RSD < 14% and <15%. The accuracy was relative error (RE) within +/- 14%. This method was applied to studying the pharmacokinetics and tissue distribution after a single dose of trimebutine maleate was administrated to the rats. The T(max), AUC, C(max) and t(1/2) were 30 min, 7.8 x 10(2) (ng/mL) min, 39 ng/mL and 1.7 x 10(2) min. The drug distribution was found in a decreasing order of liver, kidney, spleen, lung and heart.

Effects of trimebutine on intestinal motility after massive small bowel resection

Effects of trimebutine maleate (TM) on intestinal motility in short bowel syndrome (SBS) were studied in conscious canines in both acute and chronic phases following 80% massive distal small bowel resection (MSBR). TM was administered orally to beagles with MSBR or as controls in the postprandial and fasting states, and given simultaneously with meals. Intestinal motility was measured using bipolar electrodes for approximately 1 month after the electrodes were implanted in each beagle and the data compared between treatment groups. When TM was given with meals, the postprandial period without duodenal migrating myoelectric (or motor) complexes (MMCs) was shorter than in those given meals only. When TM was given in the postprandial state in short bowel beagles, the initial duodenal MMCs occurred earlier, i.e. the postprandial period was shorter. Diarrhea did not occur in these beagles. When TM was given in the fasting state, duodenal MMCs occurred and propagated to the distal intestine. In conclusion, oral TM administration can produce a more appropriate intestinal condition for the next food intake and make enteral nutrition possible even in the acute phase after MSBR. Such feeding can be carried out without overloading gut function as a result of the modulation of gastrointestinal motility by TM.

Effect of trimebutine on voltage-activated calcium current in rabbit ileal smooth muscle cells

1. The effect of trimebutine on the voltage-dependent inward Ca2+ current was investigated by the whole-cell voltage-clamp technique in single smooth muscle cells from rabbit ileum. 2. Trimebutine (3-100 microM) reduced the Ca2+ current in a concentration-dependent manner. The inhibitory effect on the Ca2+ current was also dependent on the holding potential. The Ca2+ current after a low holding potential was inhibited to a greater extent than that after a high membrane potential: the IC50 values were 7 microM and 36 microM at holding potentials of -40 mV and -60 mV, respectively. The Ca2+ current elicited from a holding potential of -80 mV could not be reduced by as much as 50% of the control by trimebutine at concentrations as high as 100 microM. 3. Trimebutine (30 microM) shifted the voltage-dependent inactivation curve for the Ca2+ current by 18 mV in the negative direction. The affinity of the drug for Ca2+ channels was calculated to be 36 times higher in the inactivated state than in the closed-available state. 4. Blockade of the Ca2+ current by trimebutine, unlike verapamil, was not use-dependent. 5. The results suggest that trimebutine inhibits the voltage-dependent inward Ca2+ current through a preferential binding to Ca2+ channels in the inactivated state in the smooth muscle cell from rabbit ileum. The inhibitory effect of trimebutine on gastrointestinal motility is discussed in the light of the present findings.

Effect of trimebutine on K+ current in rabbit ileal smooth muscle cells

The effect of trimebutine on the K+ current in rabbit ileal smooth muscle cells was investigated using the whole-cell patch-clamp technique. Trimebutine (10 microM) inhibited an outward current consisting of a Ca(2+)-dependent K+ current (IKCa) and Ca(2+)-independent K+ current (IKv), elicited by stepping from -80 to -20 mV or more positive. Trimebutine reduced dose dependently the IKv amplitude with an IC50 of 7.6 microM and IKCa amplitude with an IC50 of 23.5 microM. The IKv inhibition was neither voltage- nor use-dependent. Trimebutine (1-100 microM) decreased the amplitude and discharge rate of spontaneous transient outward currents. Trimebutine (30 microM) produced a sustained membrane depolarization of about 10 mV accompanied by a decrease in membrane conductance. The results suggest that the excitatory effects of trimebutine on the gastrointestinal tract may be attributable to the inhibitory action on the K+ current.

Effects of trimebutine on cytosolic Ca2+ and force transitions in intestinal smooth muscle

The effects of trimebutine maleate on cytosolic free Ca2+ and force transitions in the guinea-pig taenia cecum were studied by fura-2 fluorometry and tension recording. The addition of 80 mM K+ induced a transient increase in cytosolic free Ca2+ concentration ([Ca2+]i) and tension, followed by a sustained increase. Trimebutine (10 microM) suppressed both [Ca2+]i elevation and tension development. The tonic responses were more potently inhibited than the phasic responses. Phasic components gradually increased as the added K+ increased (10-40 mM). The relationship between the peak increases in [Ca2+]i and tension was not affected by trimebutine (10 microM). This means that trimebutine does not affect the Ca2+ sensitivity of contractile elements. In a high K+ and Ca(2+)-free medium, carbachol (10 microM) or caffeine (30 mM) caused transient [Ca2+]i elevation and tension development in the smooth muscle. Trimebutine (10 microM) decreased the amplitude of both responses. Trimebutine (10 microM) inhibited the spontaneous fluctuations in [Ca2+]i and motility of taenia cecum in the presence of tetrodotoxin (TTX; 0.3 microM). These results suggest that trimebutine has two types of inhibitory actions on intestinal smooth muscle; one, the inhibition of Ca2+ influx through voltage-dependent calcium channels, and the other, the inhibition of Ca2+ release from intracellular storage sites.

Allosteric interaction of trimebutine maleate with dihydropyridine binding sites

The effects of trimebutine maleate on [3H]nitrendipine binding to guinea-pig ileal smooth muscle membranes and Ca2(+)-induced contraction of the taenia cecum were studied. Specific binding of [3H]nitrendipine to smooth muscle membranes was saturable, with a KD value and maximum number of binding sites (Bmax) of 0.16 nM and 1070 fmol/mg protein, respectively. Trimebutine inhibited [3H]nitrendipine binding in a concentration-dependent manner with a Ki value of 9.3 microM. In the presence of trimebutine (10 microM), Scatchard analysis indicated a competitive-like inhibition with a decrease in the binding affinity (0.31 nM) without a change in Bmax (1059 fmol/mg protein). However, a dissociation experiment using trimebutine (10 or 100 microM) showed that the decreased affinity was due to an increase of the dissociation rate constant of [3H]nitrendipine binding to the membrane. In mechanical experiments using the taenia cecum, trimebutine (3-30 microM) caused a parallel rightward shift of the dose-response curve for the contractile response to a higher concentration range of Ca2+ under high-K+ conditions in a noncompetitive manner. These results suggest that trimebutine has negative allosteric interactions with 1,4-dihydropyridine binding sites on voltage-dependent Ca2+ channels and antagonizes Ca2+ influx, consequently inhibiting contractions of intestinal smooth muscle.

Trimebutine maleate has inhibitory effects on the voltage-dependent Ca2+ inward current and other membrane currents in intestinal smooth muscle cells

We examined effects of trimebutine maleate on the membrane currents of the intestinal smooth muscle cells by using the tight-seal whole cell clamp technique. Trimebutine suppressed the Ba2+ inward current through voltage-dependent Ca2+ channels in a dose-dependent manner. The inhibitory effect of trimebutine on the Ba2+ inward current was not use-dependent. It shifted the steady-state inactivation curve to the left along the voltage axis. Trimebutine also had inhibitory effects on the other membrane currents of the cells, such as the voltage-dependent K+ current, the Ca2(+)-activated oscillating K+ current and the acetylcholine-induced inward current. These relatively non-specific inhibitory effects of trimebutine on the membrane currents may explain, at least in part, the dual actions of the drug on the intestinal smooth muscle contractility, i.e. inhibitory as well as excitatory.

Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated duodenum and ileum in both guinea pigs and rabbits

Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated duodenum and ileum were studied in both guinea pigs and rabbits. In the duodenum and ileum of both guinea pigs and rabbits, TM-906 (10(-6) g/ml, 10(-5) g/ml) produced a potentiation of the spontaneous contraction in preparations with low contractile activity (low tone or small contraction), while it caused an inhibition of the spontaneous contraction in preparations with high contractile activity (high tone or large contraction). The potentiation of spontaneous contraction by TM-906 was more pronounced in the ileum than in the duodenum of both guinea pigs and rabbits. When the spontaneous contraction of duodenum and ileum was decreased by atropine, the potentiation of spontaneous contraction by TM-906 was further augmented and was more pronounced in the ileum than in the duodenum. When the spontaneous contraction was remarkably potentiated by physostigmine or acetylcholine, TM-906 markedly inhibited the potentiated spontaneous contraction, and the potentiation by TM-906 seen in preparations with low contractile activity disappeared. From these results, it is concluded that TM-906 produces, depending on the contractile activity of the preparations, a potentiation or an inhibition of the spontaneous contraction of duodenum and ileum in both guinea pigs and rabbits and that the potentiation by TM-906 is more pronounced in the ileum than in the duodenum. It is suggested that the endogenous acetylcholine partly modifies the effects of TM-906, but that it does not relate to the more pronounced potentiation by TM-906 in the ileum than in the duodenum.

Effect of trimebutine on colonic myoelectrical activity in IBS patients

The effect of trimebutine 100 mg i.v. and placebo on colonic myoelectrical activity was investigated in 10 patients with the irritable bowel syndrome (IBS) (5 constipated and 5 diarrhoeic), using an intraluminal probe supporting 8 groups of electrodes. At each site examined from transverse to sigmoid colon, the electromyograms exhibited two kinds of spike bursts: short spike bursts (SSB) localized at one electrode site and appearing rhythmically at 10.3/min, and long spike bursts (LSB), isolated or propagated orally or aborally. Computerized analysis of the duration of each kind of spike burst showed that, as compared to the control, trimebutine 100 mg, selectively inhibited by 43 to 73% the mean duration of LSB activity in the transverse, descending and sigmoid colon, from 0 to 30 min after administration. The inhibitory effect was similar in constipated and diarrhoeic patients. Placebo injection did not significantly affect (p greater than 0.05) the duration of LSB and SSB activity. Variance analysis indicated that the inhibitory effect of trimebutine was significantly greater (p less than 0.05) on LSB activity in the transverse than the descending colon, and that it was absent from the sigmoid colon. The results suggest that trimebutine selectively inhibits the propulsive activity of the proximal two thirds of the colon in IBS patients, and that this effect cannot entirely explain its therapeutic efficacy in IBS.

Effects of trimebutine maleate (TM-906) on the smooth muscles of isolated guinea pig gallbladder

Effects of trimebutine maleate (TM-906) on the smooth muscles of isolated guinea pig gallbladder were investigated. TM-906 inhibited the contractile responses to cholinergic nerve stimulation (5 Hz) and to acetylcholine (3 X 10(-8) g/ml) to the same extent, both of which produced much the same amplitude of contraction. TM-906 noncompetitively antagonized the contractile response to methacholine, and it caused a parallel shift of dose-response curves for the contractile response to CaCl2 to higher concentrations. Moreover, TM-906 inhibited the contractile response to 50 mM KCl in a dose-dependent manner. On the other hand, TM-906 itself evoked a slight contractile response in a dose-dependent manner. The contractile response induced by TM-906 was prevented by exposure to Ca++-free solution, but not by tetrodotoxin or atropine. From these results, it was suggested that TM-906 inhibited the contractile responses to cholinergic nerve stimulation, acetylcholine, methacholine and 50 mM KCl by reducing the influx of calcium ion across the cell membrane, while it was assumed that TM-906 itself evoked a slight contractile response by increasing in some way the concentration of the intracellular free calcium ion available for the contractile systems.

Effects of trimebutine maleate (TM-906) on electrical and mechanical activities of smooth muscles of the guinea-pig stomach

The effects of trimebutine maleate (TM-906) on electrical and mechanical activities of smooth muscles of the guinea-pig stomach were investigated using a microelectrode and isometric tension recording methods. TM-906 (2 X 10(-5) M) depolarized the membrane of smooth muscles in the antrum to about 10 mV. From the current-voltage relationship and changes in membrane potentials in various [K]0, the TM-906-induced depolarization is considered to be mainly due to a decrease in the K-conductance. TM-906 increased the amplitude of the first spike potential and regularized the rhythm of slow waves. These excitatory effects are presumably due to the K-channel-blocking action during the repolarizing phase of the spikes and to the depolarization. TM-906 reduced the amplitudes of mechanical activities and slow waves. These inhibitory effects are presumably due to the inhibition of Ca-release from storage sites and to the block of Ca-influx. The biphasic effects are possibly due to the local anesthetic properties. TM-906 modified neither the membrane potential nor the membrane conductance of circular muscles in the fundus. This may mean that the circular muscles in the fundus lack the K-channel sensitive to TM-906.