Human metabolism of [<Superscript>14</Superscript>C]indisulam following i.v. infusion in cancer patients

Indisulam is a new anticancer drug with a unique mechanism of action, arresting the cell cycle at the G1/S transition. The major excretory pathway of indisulam is via the urine, accounting for 63% of the radioactive dose ([¹⁴C]indisulam) administered in a human mass balance study. Radiochromatographic profiling of urine samples resulted in the detection of several radioactive peaks. The purpose of the present investigation was to elucidate the chemical structures of these observed indisulam metabolites. We collected fractions after chromatographic separation of the urine samples. These fractions were analysed using tandem mass spectrometry. We propose the chemical structure of 15 indisulam metabolites in urine. The metabolism of indisulam is very complex, consisting of oxidative dechlorination, hydroxylation, hydrolysis, acetylation, sulphation and glucuronidation. The clinical relevance of the observed indisulam metabolites needs further investigation.     

Pharmacokinetics,tissue distribution,metabolism, and excretion of ginsenoside Rg<Subscript>1</Subscript> in rats

The pharmacokinetics, tissue distribution, metabolism, and excretion of ginsenosides Rg₁ were studied in Wistar rats, by measuring the concentrations of Rg₁ and its metabolites in the blood, tissues, bile, urine, and feces after dosing. After intravenous (i.v.) administration, the elimination half-lives of Rg₁ and its metabolites were 1.82, 5.87, and 6.87 h, and the area under the curves were 1595.7, 597.5, and 805.6 ng· h/mL, respectively. After oral administration, the elimination half-lives of Rg₁ and its metabolites were 2.25, 6.73, 5.44, and 5.06 h, and the area under the curves were 2363.5, 4185.5, 3774.3, and 396.2 ng· h/mL, respectively. After i.v. administration, Rg₁ and its metabolites were well distributed to the tissues analyzed except for the brain. The maximum concentration of Rg₁ was reached in all tissues at 5 min post dose, and it was eliminated from most of the tissues except for the kidney faster than it was eliminated from the blood. The maximum concentration of the metabolites was reached in all tissues between 4 and 6 h post dose. After i.v. administration, the recovery of the Rg₁ prototype in the urine and bile was 27.96% and 60.77%, respectively. The metabolism of Rg₁ in the intestine was via a hydrolization pathway, with the 6- and 20-glucoside bond hydrolyzed gradually under the catalysis of β-glucosaccharase, and then the metabolites were reabsorbed into the blood. Finally, the total recovery of the Rg₁ prototype and its metabolites in the urine and feces were 51.31% and 47.46%, respectively.     

Absorption, metabolism, and excretion of 14C-labeled tapentadol HCl in healthy male subjects.

Tapentadol is a novel, centrally acting oral analgesic with a dual mode of action that has demonstrated efficacy in preclinical and clinical models of pain relief. The present study investigated and characterized the absorption, metabolism, and excretion of tapentadol in humans. Four healthy male subjects received a single 100-mg oral dose of 3-[14C]-labeled tapentadol HCl for evaluation of the pharmacokinetics of the drug and the excretion balance of radiocarbon. The concentration-time profiles of radiocarbon in whole blood and serum and radiocarbon excretion in the urine and feces, and the expired CO2 were determined. The serum pharmacokinetics and excretion kinetics of tapentadol and its conjugates were assessed, as was its tolerability. Absorption was rapid (with a mean maximum serum concentration [Cmax], 2.45 microg-eq/ml; a time to Cmax, 1.25-1.5 h), and the drug was present primarily in the form of conjugated metabolites (conjugated:unconjugated metabolites = 24:1). Excretion of radiocarbon was rapid and complete (>95% within 24 h; 99.9% within 5 days) and almost exclusively renal (99%: 69% conjugates; 27% other metabolites; 3% in unchanged form). No severe adverse events or clinically relevant changes in vital signs, laboratory measurements, electrocardiogram recording, or physical examination findings were reported. In our study group, it was found that a single oral dose of tapentadol was rapidly absorbed, then excreted into the urine, primarily in the form of conjugated metabolites, and was well tolerated.     

Inhibitory effect of YM-244769, a novel Na<Superscript>+</Superscript>/Ca<Superscript>2+</Superscript> exchanger inhibitor on Na<Superscript>+</Superscript>/Ca<Superscript>2+</Superscript> exchange current in guinea pig cardiac ventricular myocytes

Recently, YM-244769 (N-(3-aminobenzyl)-6-{4-[(3-fluorobenzyl)oxy]phenoxy} nicotinamide) has been reported as a new potent and selective Na⁺/Ca²⁺ exchange (NCX) inhibitor by using various cells transfected with NCX using the ⁴⁵Ca²⁺ fluorescent technique. However, the electrophysiological study of YM-244769 on NCX had not been performed in the mammalian heart. We examined the effects of YM-244769 on NCX current (I_NCX) in single cardiac ventricular myocytes of guinea pigs by using the whole-cell voltage clamp technique. YM-244769 suppressed the bidirectional I_NCX in a concentration-dependent manner. The IC₅₀ values of YM-244769 for the bidirectional outward and inward I_NCX were both about 0.1 μM. YM-244769 suppressed the unidirectional outward I_NCX (Ca²⁺ entry mode) with an IC₅₀ value of 0.05 μM. The effect on the unidirectional inward I_NCX (Ca²⁺ exit mode) was less potent, with 10 μM of YM-244769 resulting in the inhibition of only about 50 %. At 5 mM intracellular Na⁺ concentration, YM-244769 suppressed I_NCX more potently than it did at 0 mM [Na⁺]_i. Intracellular application of trypsin via the pipette solution did not change the blocking effect of YM-244769. In conclusion, YM-244769 inhibits the Ca²⁺ entry mode of NCX more potently than the Ca²⁺ exit mode, and inhibition by YM-244769 is [Na⁺]_i-dependent and trypsin-insensitive. These characteristics are similar to those of other benzyloxyphenyl derivative NCX inhibitors such as KB-R7943, SEA0400, and SN-6. The potency of YM-244769 as an NCX1 inhibitor is higher than those of KB-R7943 and SN-6 and is similar to that of SEA0400.     

Effects of gabapentin and pregabalin on K<Superscript>+</Superscript>-evoked <Superscript>3</Superscript>H-GABA and <Superscript>3</Superscript>H-glutamate release from human neocortical synaptosomes

One site of action of the anticonvulsant, analgesic, and anxiolytic drugs gabapentin and pregabalin is the α₂δ-subunit of voltage-sensitive Ca²⁺ channels (VSCC). We therefore analyzed the effects of gabapentin and pregabalin on K⁺-evoked release of ³H-γ-aminobutyric acid (GABA) and ³H-glutamate from superfused human neocortical synaptosomes. These neurotransmitters are released by Ca²⁺-dependent exocytosis and by Ca²⁺-independent uptake reversal. When a GABA transport inhibitor was present throughout superfusion to isolate exocytotic conditions, gabapentin and pregabalin (100 μM each) reduced K⁺-evoked ³H-GABA release by 39% and 47%, respectively. These effects were antagonized by the α₂δ-ligand l-isoleucine (1 μM) suggesting the α₂δ-subunit of terminal VSCC to mediate the reduction of exocytosis. Both drugs had no effect on exocytotic ³H-glutamate release and also failed to modulate the release of ³H-GABA and ³H-glutamate caused by reversed uptake in the absence of external Ca²⁺. Thus, an inhibition of glutamate release by gabapentin and pregabalin as main anticonvulsant principle is not supported by our experiments. An anticonvulsant mode of action of both drugs may be the reduction of a proconvulsant exocytotic GABA release.     

Magnesium isoglycyrrhizinate inhibits L-type Ca<Superscript>2+</Superscript> channels,Ca<Superscript>2+</Superscript> transients,and contractility but not hERG K<Superscript>+</Superscript> channels

To explore the cardiovascular protective effects of Magnesium isoglycyrrhizinate (MI), especially the underlying cellular mechanisms related to L-type calcium channels and myocardial contractility, and to examine the effects of MI on hERG K⁺ current expressed in HEK293 cells. We used the whole-cell patch clamp technique, video-based edge detection and dual excitation fluorescence photomultiplier systems to explore the effect of MI on L-type Ca²⁺ currents (I_Ca-L) and cell contraction in rat cardiomyocytes. We also examined the rapidly activating delayed rectifier potassium current (I_Kr) expressed in HEK293 cells using a perforated patch clamp. MI inhibited I_Ca-L in a dose-dependent manner, with a half-maximal inhibitory concentration (IC₅₀) of 0.22 mg/ml, and the maximal inhibitory effect was 61.10 ± 0.59%. MI at a concentration of 0.3 mg/ml reduced cell shortening by 24.12 ± 3.97% and the peak value of the Ca²⁺ transient by 36.54 ± 4.96%. MI had no significant influence on hERG K⁺ channels expressed in HEK293 cells at all test potentials. MI exerts protective effects on the heart via the inhibition of I_Ca-L and cell shortening in rat cardiomyocytes. However, MI had no significant influence on I_Kr; thus, MI may exert cardioprotective effects without causing drug-induced long QT syndrome.     

Abnormal activation of Na<Superscript>+</Superscript>-K<Superscript>+</Superscript> pump in aortas from rats with endotoxaemia

A diminished reactivity to several vasoconstrictor agents is usually observed in blood vessels obtained from animals with endotoxic shock. The contractile state of vascular smooth muscle is influenced by the activity of the electrogenical sodium (Na⁺-K⁺) pump. Thus, we examined inhibitors and agonists of nitric oxide (NO)-guanosine 3':5'-cyclic monophosphate (cGMP) on contractions to phenylephrine (PE) and relaxations to potassium in isolated aortic segments from rats treated with bacterial endotoxin (lipopolysaccharide, LPS) for 6 h (i.e. to mimic a shock syndrome). Endotoxaemia for 6 h was associated with a severe hypotension and vascular hyporeactivity to noradrenaline and an increased plasma nitrate level in vivo. The PE-induced contraction was attenuated in aortic smooth muscle obtained from rats with endotoxic shock while the potassium-induced relaxation was greater in these preparations. Ouabain dose-dependently inhibited the potassium-induced relaxation in aortas from normal and endotoxaemic rats. 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one enhanced the PE-induced contraction in endotoxaemic rats only, whereas it attenuated the difference of potassium-induced relaxation between normal and endotoxaemic rats. In contrast, in aortas obtained from normal rats, 8-bromo-cGMP reduced the PE-induced contraction and enhanced the potassium-induced relaxation to the level as seen in endotoxaemic animals. In aortas obtained from endotoxaemic rats, methylene blue further restored the PE-induced contraction to the normal and abolished the difference of potassium-induced relaxation between normal and endotoxaemic rats. These results suggest that the Na⁺-K⁺ pump in the vascular bed of animals with endotoxic shock is abnormally activated and this augmented activation is modulated by cGMP.     

Dopamine Increases CD14<Superscript>+</Superscript>CD16<Superscript>+</Superscript> Monocyte Transmigration across the Blood Brain Barrier: Implications for Substance Abuse and HIV Neuropathogenesis

In human immunodeficiency virus-1 (HIV) infected individuals, substance abuse may accelerate the development and/or increase the severity of HIV associated neurocognitive disorders (HAND). It is proposed that CD14⁺CD16⁺ monocytes mediate HIV entry into the central nervous system (CNS) and that uninfected and infected CD14⁺CD16⁺ monocyte transmigration across the blood brain barrier (BBB) contributes to the establishment and propagation of CNS HIV viral reservoirs and chronic neuroinflammation, important factors in the development of HAND. The effects of substance abuse on the frequency of CD14⁺CD16⁺ monocytes in the peripheral circulation and on the entry of these cells into the CNS during HIV neuropathogenesis are not known. PBMC from HIV infected individuals were analyzed by flow cytometry and we demonstrate that the frequency of peripheral blood CD14⁺CD16⁺ monocytes in HIV infected substance abusers is increased when compared to those without active substance use. Since drug use elevates extracellular dopamine concentrations in the CNS, we examined the effects of dopamine on CD14⁺CD16⁺ monocyte transmigration across our in vitro model of the human BBB. The transmigration of this monocyte subpopulation is increased by dopamine and the dopamine receptor agonist, SKF 38393, implicating D1-like dopamine receptors in the increase in transmigration elicited by this neurotransmitter. Thus, elevated extracellular CNS dopamine may be a novel common mechanism by which active substance use increases uninfected and HIV infected CD14⁺CD16⁺ monocyte transmigration across the BBB. The influx of these cells into the CNS may increase viral seeding and neuroinflammation, contributing to the development of HIV associated neurocognitive impairments.     

Radiolabeling of EGCG with <Superscript>131</Superscript>I and biodistribution in rats

Epigallocatechin gallate (EGCG), is the most abundant and widely studied catechin in green tea (Camellia sinensis Theaceae). The inhibitory effects of EGCG and green tea extract on carcinogenesis in various organs in rodents have now been demonstrated over the past decade. The aim of study was to label EGCG with I-131, to determinate its structure and to evaluate its biodistribution in Wistar rats. Radiolabeling was carried out by direct electrophilic iodination method (iodogen) and yield was determined by radio thin layer chromatography (RTLC). Radiolabelling yield is determined as 89 ± 1.0%. Besides, determination of structure of iodinated molecule, serum stability, and partition coefficient experiments was performed. The structure analysis of synthesized cold ¹²⁷I-EGCG complex was assessed with LC–MS–MS and ¹H-NMR. ¹H-NMR and LC–MS–MS results of iodinated EGCG (¹²⁷I-EGCG) show that oxidize iodine reacts electrophilic with aromatic ring. Serum stability results showed that in vitro stability of ¹³¹I-EGCG was quite high. It is observed that labeling percentage decreased 83 ± 2% at 24th, Partition coefficient results show that the partition coefficient of EGCG was calculated as theoretical partition coefficient = 2.04 ± 0.42 and the experimental partition coefficient of ¹³¹I-EGCG was found as 1.46 ± 0.2. The biodistribution data shown that the maximum uptake of the radioiodinated EGCG was seen in lung and pancreas at 30 min. The blocking assay results indicated that the uptake of ¹³¹I-EGCG in lung was not significantly change (0.25, 0.23, and 0.22%ID/g at 30, 60, and 150 min, respectively). Biodistribution data showed no significant uptake in a specific organ of the rat. Hence radiolabeled EGCG is seen in some organs (lung, liver, pancreas, kidney, etc.).     

Examination of the structure of agaricinic acid using <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR spectroscopy

Agaricinic acid was extracted from the carpophore of Fomitopsis officinalis (Vill. Bond. et Sing). Its structure was established by ¹H and ¹³C NMR spectroscopy and comparison to a standard sample (Sigma—Aldrich). The extraction was carried out using ethanol. The obtained extract was evaporated, cooled (−5°C), and purified by ether. The structure of unbranched alkyl radicals was determined using their proton spectrum. The ¹³C NMR spectrum and two-dimensional {¹³C,¹H} correlation diagram showed the presence of a hydroxyl (second quaternary C atom) and three types of carboxy groups (first, second, and third C atoms). The spectrum of the extracted sample is identical to that of the standard sample of agaricinic acid.     

The Tritiated Water Skin Barrier Integrity Test: Considerations for Acceptance Criteria with and Without <Superscript>14</Superscript>C-Octanol

Purpose

A study was designed to assess barrier integrity simultaneously using separate compounds (probes) for polar and non-polar pathways through the skin, ³H₂O and ¹⁴C-octanol, respectively; and to determine whether the two probe approach could better define barrier integrity.

Methods

A 5-min dose of water containing ³H₂O and ¹⁴C -octanol was applied to ex vivo human skin mounted in Franz diffusion cells. The receptor solution was sampled at 30 min, analyzed for ³H and ¹⁴C content, and the correlation between water and octanol absorption was determined by statistical tests suitable for non-normally distributed data. This study was conducted on skin from 37 donors with from 3 to 30 replicate skin sections per donor (a total of 426 sections).

Results

The correlation between ³H₂O and ¹⁴C-octanol absorption was low (Pearson correlation coefficient?=?0.3485). The ³H₂O absorption cutoff used in this study to select for a normal skin barrier rejected some sections in which ¹⁴C-octanol absorption was within normal limits and accepted others in which ¹⁴C-octanol absorption was abnormally high. The converse was true for ³H₂O absorption when the ¹⁴C-octanol-based cutoff was used.

Conclusions

The results of the ³H₂O test or of similar tests that primarily assess the permeability of polar pathways through the skin may not necessarily provide information relevant to the absorption of highly lipophilic compounds. Octanol, or another molecule that more closely matches the physicochemical attributes of the test compound, may characterize properties of the skin barrier that are more relevant to compounds of low water solubility.

     

Reduction of myocardial infarct size by SM-198110, a novel Na<Superscript>+</Superscript>/H<Superscript>+</Superscript> exchange inhibitor,in rabbits

The effects of 3-[2-({[amino(imino)methyl]amino}carbonyl)-4-chloro-1H-indol-1-yl]-1-propanesulphonic acid monohydrate (SM-198110), a novel potent Na⁺/H⁺ exchange inhibitor, and cariporide (Hoe642), another Na⁺/H⁺ exchange inhibitor, were studied in a myocardial ischaemia and reperfusion injury model. Anaesthetized rabbits were subjected to occlusion of the coronary artery for 30 min followed by reperfusion for 5 h. SM-198110 or cariporide was administered before ischaemia and before reperfusion. We also assessed the anti-necrotic effect of SM-198110 when given before reperfusion, both alone and together with glibenclamide, a K_ATP channel blocker, 5-hydroxydecanoate (5-HD), a mitochondrial K_ATP channel-selective blocker and 8-(p-sulphophenyl)-theophylline (8-SPT), an adenosine receptor blocker. The infarct size was reduced dose-dependently by i.v. administration of SM-198110 before ischaemia, with a significant reduction in serum creatine phosphokinase activity. Infarct sizes, normalized to the size of the area-at-risk (means±SE) were: vehicle 56.6±3.7%; low-dose SM-198110 39.2±6.3%; mid-dose 32.8±7.4% (P<0.05); high-dose 22.1±6.7% (P<0.01). This anti-necrotic effect of SM-198110 was achieved without significant haemodynamic changes. Cariporide given before ischaemia also reduced infarct size significantly and dose-dependently. SM-198110 administered before reperfusion also resulted in a dose-dependent reduction in the infarct size. Infarct sizes were: vehicle 56.6±3.7%; low-dose SM-198110 44.5±5.7%; mid-dose 36.3±6.6% (P<0.01); high-dose 34.7±3.8% (P<0.01). In contrast, cariporide given before reperfusion did not reduce infarct sizes significantly. The anti-necrotic effect of SM-198110 was observed even when given 10 min after the beginning of reperfusion. Glibenclamide and 5-HD abolished the anti-necrotic effect of treatment before reperfusion with SM-198110. However, the co-administration of 8-SPT with SM-198110 did not affect infarct size. These results suggest that, in addition to Na⁺/H⁺ exchange inhibition, mitochondrial and/or sarcolemmal K_ATP channels contribute to the anti-necrotic effect of SM-198110 when the latter is given before reperfusion.     

Effects of trimebutine maleate on colonic motility through Ca<Superscript>2+</Superscript>-activated K<Superscript>+</Superscript> channels and L-type Ca<Superscript>2+</Superscript> 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 Ca²⁺-activated K⁺ (BK_ca) and L-type Ca²⁺ 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 Ca²⁺ 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 Ca²⁺ channel opener, increased L-type Ca²⁺ currents. This augmentation was also attenuated by TM. These results suggest that TM attenuates intestinal motility through inhibition of L-type Ca²⁺ currents, and depolarizes membrane potentials by reducing BK_ca currents. Thus, TM may be a multiple-ion channel regulator in the gastrointestinal tract.     

Differential modulation of K<Superscript>+</Superscript>-evoked <Superscript>3</Superscript>H-neurotransmitter release from human neocortex by gabapentin and pregabalin

Anticonvulsant, analgesic, and anxiolytic effects have been observed both in preclinical and clinical studies with gabapentin (GBP) and pregabalin (PGB). These drugs appear to act by binding to the α₂δ subunit of voltage-sensitive Ca²⁺ channels (VSCC), resulting in the inhibition of neurotransmitter release. In this study, we examined the effects of GBP and PGB (mostly 100 μM, corresponding to relatively high preclinical/clinical plasma levels) on the release of neurotransmitters in human neocortical slices. These slices were prelabeled with ³H-dopamine (³H-DA), ³H-choline (to release ³H-acetylcholine (³H-ACh)), ³H-noradrenaline (³H-NA), and ³H-serotonin (³H-5-HT), and stimulated twice in superfusion experiments by elevation of extracellular K⁺ in the presence and absence of GBP and PGB. The α₂δ ligands produced significant inhibitions of K⁺-evoked ³H-ACh, ³H-NA, and ³H-5-HT release between 22% and 56% without affecting ³H-DA release. Neither drug reduced ³H-NA release in the presence of l-isoleucine, a putative α₂δ antagonist. Interestingly, this antagonism did not occur using the enantiomer, d-isoleucine. These results suggest that GBP and PGB are not general inhibitors of VSCC and neurotransmitter release. Such α₂δ ligands appear to be selective modulators of the release of certain, but not all, neurotransmitters. This differential modulation of neurotransmission presumably contributes to their clinical profile. A preliminary report of this work was presented at the German Society for Experimental and Clinical Pharmacology and Toxicology, Mainz, Germany, March 13–15, 2007 (Brawek et al. 2007).     

Pharmacokinetics of 4-acetylaminophenylacetic acid. 1st communication: absorption, distribution, metabolism and excretion in mice, rats, dogs and monkeys after single administration of 14C-labeled compound

Absorption, distribution, metabolism and excretion of 4-acetylaminophenylacetic acid (MS-932) were studied in mice, rats, dogs and monkeys after intravenous or oral administration of 5 or 10 mg/kg of 14C-MS-932. After the intravenous injection of 14C-MS-932, the radioactivity concentrations in the plasma decreased biexponentially. The half-lives of the elimination phase (t1/2, beta) were 2.58 h for mice, 2.35 h for rats, 1.88 h for dogs and 1.24 h for monkeys. After the oral administration of 14C-MS-932, the radioactivity concentrations in the plasma reached maximums between 0.4 and 1.3 h, thereafter decreasing with half-lives similar to those found for the intravenous injection. The systemic availability of this drug was 72-100% in all the species tested. No clear sex-related difference in radioactivity concentrations was found in rat plasma. After both intravenous and oral administrations, in all the species tested, almost all the radioactivity administered was excreted in the urine. Biliary excretion of radioactivity in bile duct-cannulated rats was only 1.42% of the intravenous dose over a 24-h period. Lymphatic absorption of radioactivity was negligible (0.2% of the dose over a 6-h period). After oral administration of 14C-MS-932, the radioactivity concentrations in the rat tissues tested reached maximums within 1 h, decreasing rapidly thereafter similar to the decrease in the concentration in the plasma. Much higher concentrations were present in the kidney and gastro-intestinal tract than in the plasma, whereas the concentrations in the other tissues were lower. Results obtained by whole-body autoradiography were consistent with those obtained for the radioactivity in excised tissues.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impaired platelet [<Superscript>3</Superscript>H]paroxetine binding in female patients with borderline personality disorder

Rationale There have been few studies of platelet paroxetine binding in borderline personality disorder (BPD). Objective Our aim was to determine whether female BPD subjects show abnormalities in platelet paroxetine binding. Methods Twenty-one female BPD subjects and 16 age- and gender-matched normal control subjects were assessed using the following: (1) Diagnostic Interview for Borderlines, Revised, (2) Diagnostic Assessment for Personality Pathology: Brief Questionnaire, and (3) Barratt Impulsivity Scale. Platelets were collected and assayed for platelet paroxetine binding. Results B _max was lower in the BPD group (p<0.0001), but differences in K _d only reached a trend level. There were no associations with trait dimensions independent of diagnosis. Conclusions Reduced platelet paroxetine binding in female BPD patients may reflect presynaptic serotonin dysfunction. This work was funded by the Medical Research Council of Canada     

Roles of Na<Superscript>+</Superscript>/Ca<Superscript>2+</Superscript> exchanger isoforms NCX1 and NCX2 in motility in mouse ileum

The Na⁺/Ca²⁺ exchanger (NCX) is a plasma membrane transporter that is involved in regulating intracellular Ca²⁺ concentrations in various tissues. The physiological roles by which NCX influences gastrointestinal motility are incompletely understood, although its role in the heart, brain, and kidney has been widely investigated. In this study, we focused on the functions of the NCX isoforms, NCX1 and NCX2, in the motility of the ileum in the gastrointestinal tract. We investigated the response to electric field stimulation (EFS) in the longitudinal smooth muscle of the ileum obtained from wild-type mice (WT), NCX1-heterozygote knockout mice (NCX1 HET), NCX2 HET and smooth muscle-specific NCX1.3 transgenic mice (NCX1.3 Tg). EFS induced a phasic contraction that persisted during EFS and a tonic contraction that occurred after the end of EFS. We found that the amplitudes of the phasic and tonic contractions were significantly smaller in NCX2 HET, but not in NCX1 HET, compared to WT. Moreover, the magnitudes of acetylcholine (ACh)- and substance P (SP)-induced contractions of NCX2 HET, but not of NCX1 HET, were smaller compared to WT. In contrast, the amplitudes of the phasic and tonic contractions were greater in NCX1.3 Tg compared to WT. Similar to EFS, the magnitude of ACh-induced contraction was greater in NCX1.3 Tg than in WT. Taken together, our findings indicated that NCX1 and NCX2 play important roles in ileal motility and suggest that NCX1 and NCX2 regulate the motility in the ileum by controlling the sensitivity of smooth muscles to ACh and SP.