Alpha-linolenic acid selectively inhibits the contraction of pig coronary arteries mediated through prostanoid TP receptors.

We examined the inhibitory effects of α-linolenic acid (ALA) on the contractions of pig coronary arteries. ALA concentration-dependently inhibited the contractions elicited by U46619 and prostaglandin F2α without affecting those elicited by 80 mM KCl, histamine, acetylcholine, and serotonin. ALA rightward shifted the concentration-response curve of U46619, and Schild plot analysis revealed that ALA competitively antagonized U46619. Furthermore, ALA inhibited the increase in intracellular Ca2+ concentration caused by TP receptor stimulation but not that caused by FP receptor stimulation. These results suggest that ALA behaves as a selective antagonist of TP receptors in coronary arteries.

Inhibitory mechanisms of docosahexaenoic acid on carbachol-, angiotensin II-, and bradykinin-induced contractions in guinea pig gastric fundus smooth muscle.

We studied the inhibitory actions of docosahexaenoic acid (DHA) on the contractions induced by carbachol (CCh), angiotensin II (Ang II), and bradykinin (BK) in guinea pig (GP) gastric fundus smooth muscle (GFSM), particularly focusing on the possible inhibition of store-operated Ca2+ channels (SOCCs). DHA significantly suppressed the contractions induced by CCh, Ang II, and BK; the inhibition of BK-induced contractions was the strongest. Although all contractions were greatly dependent on external Ca2+, more than 80% of BK-induced contractions remained even in the presence of verapamil, a voltage-dependent Ca2+ channel inhibitor. BK-induced contractions in the presence of verapamil were not suppressed by LOE-908 (a receptor-operated Ca2+ channel (ROCC) inhibitor) but were suppressed by SKF-96365 (an SOCC and ROCC inhibitor). BK-induced contractions in the presence of verapamil plus LOE-908 were strongly inhibited by DHA. Furthermore, DHA inhibited GFSM contractions induced by cyclopiazonic acid (CPA) in the presence of verapamil plus LOE-908 and inhibited the intracellular Ca2+ increase due to Ca2+ addition in CPA-treated 293T cells. These findings indicate that Ca2+ influx through SOCCs plays a crucial role in BK-induced contraction in GP GFSM and that this inhibition by DHA is a new mechanism by which this fatty acid inhibits GFSM contractions.

Platelet-activating factor contracts guinea pig esophageal muscularis mucosae by stimulating extracellular Ca2+ influx through diltiazem-insensitive Ca2+ channels.

Platelet-activating factor (PAF) is expected to increase esophageal motility. However, to the best of our knowledge, this has not been examined. Thus, we investigated the contractile effects of PAF on guinea pig (GP) esophageal muscularis mucosae (EMM) and the extracellular Ca2+ influx pathways responsible. PAF (10-9-10-6 M) contracted EMM in a concentration-dependent manner. PAF (10-6 M)-induced contractions were almost completely suppressed by apafant (a PAF receptor antagonist, 3 × 10-5 M). In EMM strips, PAF receptor and PAF-synthesizing/degrading enzyme mRNAs were detected. PAF (10-6 M)-induced contractions were abolished by extracellular Ca2+ removal but were not affected by diltiazem [a voltage-dependent Ca2+ channel (VDCC) inhibitor, 10-5 M]. PAF (10-6 M)-induced contractions in the presence of diltiazem were significantly suppressed by LOE-908 [a receptor-operated Ca2+ channel (ROCC) inhibitor, 3 × 10-5 M], SKF-96365 [an ROCC and store-operated Ca2+ channel (SOCC) inhibitor, 3 × 10-5 M], and LOE-908 plus SKF-96365. Among the tested ROCC/SOCC-related mRNAs, Trpc3, Trpc6, and Trpv4/Orai1, Orai3, and Stim2 were abundantly expressed in EMM strips. These results indicate that PAF potently induces GP EMM contractions that are dependent on extracellular Ca2+ influx through ROCCs/SOCCs, and VDCCs are unlikely to be involved.

Inhibitory Actions of Antidepressants, Hypnotics, and Anxiolytics on Recombinant Human Acetylcholinesterase Activity.

Alzheimer's disease (AD) is accompanied by behavioral and psychological symptoms of dementia (BPSD), which is often alleviated by treatment with psychotropic drugs, such as antidepressants, hypnotics, and anxiolytics. If these drugs also inhibit acetylcholinesterase (AChE) activity, they may contribute to the suppression of AD progression by increasing brain acetylcholine concentrations. We tested the potential inhibitory effects of 31 antidepressants, 21 hypnotics, and 12 anxiolytics on recombinant human AChE (rhAChE) activity. At a concentration of 10-4 M, 22 antidepressants, 19 hypnotics, and 11 anxiolytics inhibited rhAChE activity by <20%, whereas nine antidepressants (clomipramine, amoxapine, setiptiline, nefazodone, paroxetine, sertraline, citalopram, escitalopram, and mirtazapine), two hypnotics (triazolam and brotizolam), and one anxiolytic (buspirone) inhibited rhAChE activity by ≥20%. Brotizolam (≥10-6 M) exhibited stronger inhibition of rhAChE activity than the other drugs, with its pIC50 value being 4.57 ± 0.02. The pIC50 values of the other drugs were <4, and they showed inhibitory activities toward rhAChE at the following concentrations: ≥3 × 10-6 M (sertraline and buspirone), ≥10-5 M (amoxapine, nefazodone, paroxetine, citalopram, escitalopram, mirtazapine, and triazolam), and ≥3 × 10-5 M (clomipramine and setiptiline). Among these drugs, only nefazodone inhibited rhAChE activity within the blood concentration range achievable at clinical doses. Therefore, nefazodone may not only improve the depressive symptoms of BPSD through its antidepressant actions but also slow the progression of cognitive symptoms of AD through its AChE inhibitory actions.

Pharmacological study on the enhancing effects of U46619 on guinea pig urinary bladder smooth muscle contraction induced by acetylcholine and α,ß-methylene ATP and the possible involvement of protein kinase C.

We examined whether U46619 (a prostanoid TP receptor agonist) could enhance the contractions of guinea pig urinary bladder smooth muscle (UBSM) in response to acetylcholine (ACh) and an ATP analog (α,ß-methylene ATP (αß-MeATP)) through stimulation of the UBSM TP receptor and whether protein kinase C (PKC) is involved. U46619 (10-7 M) markedly enhanced UBSM contractions induced by electrical field stimulation and ACh/αß-MeATP (3 × 10-6 M each), the potentiation of which was completely suppressed by SQ 29,548 (a TP receptor antagonist, 6 × 10-7 M). PKC inhibitors did not attenuate the ACh-induced contractions enhanced by U46619 although they partly suppressed the U46619-enhanced, αß-MeATP-induced contractions. While phorbol 12-myristate 13-acetate (PMA, a PKC activator, 10-6 M) did not enhance ACh-induced contractions, it enhanced αß-MeATP-induced contractions, an effect that was completely suppressed by PKC inhibitors. αß-MeATP-induced contractions, both with and without U46619 enhancement, were strongly inhibited by diltiazem. U46619/PMA enhanced 50 mM KCl-induced contractions, the potentiation of which was partly/completely attenuated by PKC inhibitors. These findings suggest that U46619 potentiates parasympathetic nerve-associated UBSM contractions by stimulating UBSM TP receptors. PKC-increased Ca2+ influx through voltage-dependent Ca2+ channels may partially play a role in purinergic receptor-mediated UBSM contractions enhanced by TP receptor stimulation.

Pharmacological Studies on the Ca2+ Influx Pathways in Platelet-Activating Factor (PAF)-Induced Mouse Urinary Bladder Smooth Muscle Contraction.

Platelet-activating factor (PAF) not only acts as a mediator of platelet aggregation, inflammation, and allergy responses but also as a constrictor of various smooth muscle (SM) tissues, including gastrointestinal, tracheal/bronchial, and pregnancy uterine SMs. Previously, we reported that PAF induces basal tension increase (BTI) and oscillatory contraction (OC) in mouse urinary bladder SM (UBSM). In this study, we examined the Ca2+ influx pathways involved in PAF-induced BTI and OC in the mouse UBSM. PAF (10-6 M) induced BTI and OC in mouse UBSM. However, the PAF-induced BTI and OC were completely suppressed by extracellular Ca2+ removal. PAF-induced BTI and OC frequencies were markedly suppressed by voltage-dependent Ca2+ channel (VDCC) inhibitors (verapamil (10-5 M), diltiazem (10-5 M), and nifedipine (10-7 M)). However, these VDCC inhibitors had a minor effect on the PAF-induced OC amplitude. The PAF-induced OC amplitude in the presence of verapamil (10-5 M) was strongly suppressed by SKF-96365 (3 × 10-5 M), an inhibitor of receptor-operated Ca2+ channel (ROCC) and store-operated Ca2+ channel (SOCC), but not by LOE-908 (3 × 10-5 M) (an inhibitor of ROCC). Overall, PAF-induced BTI and OC in mouse UBSM depend on Ca2+ influx and the main Ca2+ influx pathways in PAF-induced BTI and OC may be VDCC and SOCC. Of note, VDCC may be involved in PAF-induced BTI and OC frequency, and SOCC might be involved in PAF-induced OC amplitude.

Platelet-activating factor (PAF) enhances guinea pig detrusor smooth muscle contractile activities by stimulating voltage-dependent Ca2+ channels and store-operated Ca2+ channels.

We investigated the extracellular Ca2+ influx pathways involved in platelet-activating factor (PAF)-enhanced guinea pig detrusor smooth muscle (DSM) contractile activities. One micromolar PAF-enhanced DSM contractile activities were completely inhibited by extracellular Ca2+ removal and strongly suppressed by voltage-dependent Ca2+ channel (VDCC) inhibitors. PAF-enhanced DSM contractile activities remaining in the presence of verapamil (10 µM) were not inhibited by LOE-908 (30 µM, an inhibitor of receptor-operated Ca2+ channels (ROCCs)), but were almost completely inhibited by SKF-96365 (30 µM, an inhibitor of store-operated Ca2+ channels (SOCCs) and ROCCs). These results suggest that VDCCs and SOCCs are responsible for PAF-enhanced DSM contractile activities.

Phenylephrine-Induced Contraction in Guinea Pig Thoracic Aorta Is Triggered by Stimulation of α1L-Adrenoceptors Functionally Coupled with Store-Operated Ca2+ Channels and Voltage-Dependent Ca2+ Channels.

We examined whether the α1L-adrenoceptor (AR), which shows low affinity (pA2 < 9) for prazosin (an α1-AR antagonist) and high affinity (pA2 ≈ 10) for tamsulosin/silodosin (α1A-AR antagonists), is involved in phenylephrine-induced contractions in the guinea pig (GP) thoracic aorta (TA). Intracellular signaling induced by α1L-AR activation was also examined by focusing on Ca2+ influx pathways. Tension changes of endothelium-denuded TAs were isometrically recorded and mRNA encoding α-ARs/Ca2+ channels and their related molecules were measured using RT-quantitative PCR. Phenylephrine-induced contractions were competitively inhibited by prazosin/tamsulosin, and their pA2 value were calculated to be 8.53/9.74, respectively. These contractions were also inhibited by silodosin concentration-dependently. However, the inhibition was not competitive fashion with the apparent pA2 value being 9.48. In contrast, phenylephrine-induced contractions were not substantially suppressed by L-765314 (an α1B-AR antagonist), BMY 7378 (an α1D-AR antagonist), yohimbine, and idazoxan (α2-AR antagonists). Phenylephrine-induced contractions were markedly inhibited by YM-254890 (a Gq protein inhibitor) or removal of extracellular Ca2+, and partially inhibited by verapamil (a voltage-dependent Ca2+ channel (VDCC) inhibitor). The residual contractions in the presence of verapamil were slightly inhibited by LOE 908 (a receptor-operated Ca2+ channel (ROCC) inhibitor) and strongly inhibited by SKF-96365 (a store-operated Ca2+ channel (SOCC) and ROCC inhibitor). Among the mRNA encoding α-ARs/SOCC-related molecules, α1A-AR (Adra1a)/Orai3, Orai1, and Stim2 were abundant in this tissue. In conclusion, phenylephrine-induced contractions in the GP TA can be triggered by stimulation of Gq protein-coupled α1L-AR, followed by activation of SOCCs and VDCCs.

Dimethyl Sulfoxide Enhances Acetylcholine-Induced Contractions in Rat Urinary Bladder Smooth Muscle by Inhibiting Acetylcholinesterase Activities.

Dimethyl sulfoxide (DMSO) has been used not only as an experimental solvent, but also as a therapeutic agent for interstitial cystitis. The therapeutic effects of DMSO on interstitial cystitis are presumed to involve anti-inflammatory and analgesic effects. However, the effects of DMSO on urinary bladder smooth muscle (UBSM) have not been fully investigated. Thus, in this study, we investigated the effects of DMSO on rat UBSM contractions, and these effects were compared with those of acetone, which has a structure in which the sulfur of DMSO is replaced with carbon. DMSO (0.5-5%) enhanced acetylcholine (ACh)-induced contractions, whereas acetone (3 and 5%) suppressed them. Additionally, DMSO (5%) suppressed carbachol-induced contractions. DMSO/acetone (0.5-5%) inhibited 80 mM KCl-induced contractions in a concentration-dependent manner; however, the inhibitory effects of DMSO were weaker than those of acetone. The enhancing/suppressing effects of DMSO and acetone were almost completely abolished by wash out. DMSO and acetone (0.5-5%) inhibited recombinant human acetylcholinesterase (rhAChE) activity in a concentration-dependent manner. At 0.5 and 1%, the inhibitory effects of DMSO on rhAChE activity were more potent than those of acetone. These findings suggest that DMSO can enhance ACh-induced UBSM contractions and promote urinary bladder motility by inhibiting acetylcholinesterase (AChE), although DMSO also inhibits Ca2+ influx-mediated UBSM contractions. In addition, the sulfur atom in DMSO might play an important role in its enhancing effect on ACh-induced contractions by inhibiting AChE, as acetone did not enhance these contractions.

Eicosapentaenoic acid (EPA)-induced inhibitory effects on porcine coronary and cerebral arteries involve inhibition of prostanoid TP receptors.

This study was performed to elucidate whether eicosapentaenoic acid (EPA) suppresses spasm-prone blood vessel contractions induced by a thromboxane mimetic (U46619) and prostaglandin F2α (PGF2α) and determine whether the primary target of EPA is the prostanoid TP receptor. Accordingly, we assessed: (1) the tension changes in porcine basilar and coronary arteries, and (2) changes in the Fura-2 (an intracellular Ca2+ indicator) fluorescence intensity ratio at 510 nm elicited by 340/380 nm excitation (F340/380) in 293T cells expressing the human TP receptor (TP-293T cells) and those expressing the human prostanoid FP receptor (FP-293T cells). EPA inhibited both porcine basilar and coronary artery contractions induced by U46619 and PGF2α in a concentration-dependent manner, but it did not affect the contractions induced by 80 mM KCl. EPA also inhibited the increase in F340/380 induced by U46619 and PGF2α in TP-293T cells. In contrast, EPA showed only a marginal effect on the increase in F340/380 induced by PGF2α in FP-293T cells. These findings indicate that EPA strongly suppresses the porcine basilar and coronary artery contractions mediated by TP receptor and that inhibition of TP receptors partly underlies the EPA-induced inhibitory effects on these arterial contractions.

Effects of NP-1815-PX, a P2X4 Receptor Antagonist, on Contractions in Guinea Pig Tracheal and Bronchial Smooth Muscles.

Administration of a P2X4 receptor antagonist to asthma model mice improved asthma symptoms, suggesting that P2X4 receptor antagonists may be new therapeutics for asthma. However, the effects of these antagonists on tracheal/bronchial smooth muscle (TSM and BSM) have not been investigated. This study examined the effects of NP-1815-PX, a selective P2X4 receptor antagonist, on guinea pig TSM and BSM contractions. In epithelium-intact TSM, NP-1815-PX (10-5 M) strongly suppressed ATP-induced contractions. ATP-induced contractions were strongly suppressed by indomethacin (3 × 10-6 M) and ONO-8130 (a prostanoid EP1 receptor antagonist, 10-7 M). ATP-induced contractions were partially suppressed by SQ 29,548 (a prostanoid TP receptor antagonist, 3 × 10-7 M), although the difference was not significant. In contrast, ATP-induced contractions were not affected by AL 8810 (a prostanoid FP receptor antagonist, 10-5 M) or L-798,106 (a prostanoid EP3 receptor antagonist, 10-8 M). NP-1815-PX (10-5-10-4 M) strongly suppressed U46619 (a TP receptor agonist)- and prostaglandin F2α (PGF2α)-induced epithelium-denuded TSM and BSM contractions, which were largely inhibited by SQ 29,548. Additionally, NP-1815-PX (10-5-10-4 M) strongly suppressed the U46619-induced increase in intracellular Ca2+ concentrations in human TP receptor-expressing cells. However, NP-1815-PX (10-4 M) did not substantially inhibit the TSM/BSM contractions induced by carbachol, histamine, neurokinin A, or 50 mM KCl. These findings indicate that NP-1815-PX inhibits guinea pig TSM and BSM contractions mediated through the TP receptor, in addition to the P2X4 receptor, whose stimulation mainly induces EP1 receptor-related mechanisms. Thus, these findings support the usefulness of NP-1815-PX as a therapeutic drug for asthma.

Docosahexaenoic acid and eicosapentaenoic acid strongly inhibit prostanoid TP receptor-dependent contractions of guinea pig gastric fundus smooth muscle.

The inhibitory effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and linoleic acid (LA) on the contractions induced by five prostanoids and U46619 (a TP receptor agonist) were examined in guinea pig gastric fundus smooth muscle (GFSM). Tension changes were isometrically measured, and the mRNA expression of prostanoid receptors was measured by RT-qPCR. DHA and EPA significantly inhibited contractions induced by the prostanoids and U46619, whereas LA inhibited those induced by prostaglandin D2 and U46619. The mRNA expression levels of the prostanoid receptors were TP ≈ EP3  >> FP > EP1 . The inhibition by DHA, EPA, and LA was positively correlated with that by SQ 29,548 (a TP receptor antagonist) but not with that by L-798,106 (an EP3 receptor antagonist). DHA and EPA suppressed high KCl-induced contractions by 35% and 25%, respectively, and the contractions induced by the prostanoids and U46619 were suppressed by verapamil, a voltage-dependent Ca2+ channel (VDCC) inhibitor, by 40%-85%. Although LA did not suppress high KCl-induced contractions, it suppressed U46619-induced contractions in the presence of verapamil. However, LA did not show significant inhibitory effects on U46619-induced Ca2+ increases in TP receptor-expressing cells. In contrast, LA inhibited U46619-induced contractions in the presence of verapamil, which was also suppressed by SKF-96365 (a store-operated Ca2+ channel [SOCC] inhibitor). These findings suggest that the TP receptor and VDCC are targets of DHA and EPA to inhibit prostanoid-induced contractions of guinea pig GFSM, and SOCCs play a significant role in LA-induced inhibition of U46619-induced contractions.

Platelet-activating factor (PAF) strongly enhances contractile mechanical activities in guinea pig and mouse urinary bladder.

In this study, we investigated the effects of platelet-activating factor (PAF) on the basal tone and spontaneous contractile activities of guinea pig (GP) and mouse urinary bladder (UB) smooth muscle (UBSM) tissues to determine whether PAF could induce UBSM tissue contraction. In addition, we examined the mRNA expression of the PAF receptor, PAF-synthesizing enzyme (lysophosphatidylcholine acyltransferase, LPCAT), and PAF-degrading enzyme (PAF acetylhydrolase, PAF-AH) in GP and mouse UB tissues using RT-qPCR. PAF (10-9-10-6 M) strongly enhanced the basal tone and spontaneous contractile activities (amplitude and frequency) of GP and mouse UBSM tissues in a concentration-dependent manner. The enhancing effects of PAF (10-6 M) on both GP and mouse UBSM contractile activities were strongly suppressed by pretreatment with apafant (a PAF receptor antagonist, GP: 10-5 M; mouse: 3 × 10-5 M). The PAF receptor (Ptafr), LPCAT (Lpcat1, Lpcat2), and PAF-AH (Pafah1b3, Pafah2) mRNAs were detected in GP and mouse UB tissues. These findings reveal that PAF strongly enhances the contractile mechanical activities of UBSM tissues through its receptor and suggest that the PAF-synthesizing and -degrading system exists in UBSM tissues. PAF may serve as both an endogenous UBSM constrictor and an endogenous mediator leading to detrusor overactivity.

Docosahexaenoic Acid Selectively Suppresses U46619- and PGF2α-Induced Contractions in Guinea Pig Tracheal Smooth Muscles.

We investigated the potential inhibitory effects of docosahexaenoic acid (DHA) on the contractions of guinea pig tracheal smooth muscles in response to U46619 (a thromboxane A2 (TXA2) mimetic) and prostaglandin F2α (PGF2α) to examine whether this n-3 polyunsaturated fatty acid suppresses prostanoid-induced tracheal contractions. DHA (3 × 10-5 M) significantly suppressed tracheal contractions elicited by lower concentrations of U46619 (10-8 M) and PGF2α (5 × 10-7 M) (vs. control), although it did not suppress the contractions induced by higher concentrations (U46619: 10-7 M; PGF2α: 10-5 M). Supporting these findings, DHA (4 × 10-5 M/6 × 10-5 M) shifted the concentration-response curves for U46619 (10-9-10-6 M) and PGF2α (10-8-10-5 M) to the right. However, the slope of the regression line in the Schild plot of DHA vs. U46619/PGF2α was larger than unity. The tracheal contractions induced by U46619 (10-8 M) and PGF2α (5 × 10-7 M) were significantly suppressed by the prostanoid TP receptor antagonist SQ 29,548 (10-6 M) (vs. ethanol-treated). In contrast, DHA (4 × 10-5 M) did not show significant inhibitory effects on the contractions induced by acetylcholine (10-8-10-4 M), histamine (10-8-10-4 M), and leukotriene D4 (10-11-10-7 M) (vs. ethanol-treated). These findings indicate that DHA selectively suppresses tracheal contractions induced by U46619 and PGF2α. Therefore, DHA may be a useful therapeutic agent against asthma associated with tracheal/bronchial hyper-constriction caused by prostanoids including TXA2 and PGF2α.

Prostanoid TP receptor stimulation enhances contractile activities in guinea pig urinary bladder smooth muscle through activation of Ca2+ entry channels: Potential targets in the treatment of urinary bladder contractile dysfunction.

AIMS: We examined the potential stimulatory effects of U46619 (a prostanoid TP receptor agonist) and five prostanoids on the contractile activities of urinary bladder smooth muscle (UBSM), focusing on the role of the TP receptor and its associated Ca2+ influx routes to understand the roles of prostanoids in the regulation of UB contractile activity. MAIN METHODS: Changes in the basal tone and spontaneous contractile activity (amplitude and frequency) of isolated guinea pig UBSM were measured isotonically. The presence of TP receptors in UBSM was examined by RT-qPCR and immunofluorescence. KEY FINDINGS: U46619, prostaglandin (PG) E2, PGF2α, and PGA2 enhanced UBSM basal tone and spontaneous contractile activities, which were measured as amplitudes and frequencies. The enhancing effects of U46619 were completely suppressed by SQ 29,548 (a TP receptor antagonist), which also partially suppressed the stimulating effects of other prostanoids. The expression of TP receptors in UBSMs was verified at the mRNA and protein level. The enhancing effects of U46619 completely disappeared in Ca2+-free solution. U46619-enhanced basal tone was completely suppressed by verapamil, an inhibitor of voltage-dependent Ca2+ channels (VDCCs), and verapamil strongly decreased the spontaneous contraction frequency. The spontaneous contractions remaining in the presence of verapamil were strongly suppressed by SKF-96365 (an inhibitor of receptor-operated Ca2+ channels (ROCCs)/store-operated Ca2+ channels (SOCCs)), but not by LOE-908 (an inhibitor of ROCCs). SIGNIFICANCE: Prostanoids can enhance UBSM contractile activities and thus may be endogenous candidates for induction of detrusor overactivity. The TP receptor and TP-receptor-activated VDCCs/SOCCs are key molecules responsible for these effects.

Docosahexaenoic Acid and Eicosapentaenoic Acid Inhibit the Contractile Responses of the Guinea Pig Lower Gastrointestinal Tract.

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are n-3 polyunsaturated fatty acids (PUFAs), and are abundant in fish oil. These n-3 PUFAs have been reported to improve the lower gastrointestinal (LGI) disorders such as ulcerative colitis and Crohn's disease through their anti-inflammatory effects. However, there are few studies on the effect of n-3 PUFAs on motility of the LGI tract, such as the ileum and colon, the parts frequently affected by these inflammatory disorders. To elucidate the effects of DHA and EPA on the LGI tract motility, we performed comparative evaluation of their effects and linoleic acid (LA), an n-6 PUFA, on contractions in the ileal and colonic longitudinal smooth muscles (LSMs) isolated from guinea pigs. In the ileal and colonic LSMs, DHA and EPA (3 × 10-5 M each) significantly inhibited contractions induced by acetylcholine (ACh), histamine, and prostaglandin (PG) F2α (vs. control), and these effects are stronger than that of LA (3 × 10-5 M). In the colonic LSMs, DHA and EPA also significantly inhibited contractions induced by PGD2 (vs. control). In addition, DHA and EPA significantly inhibited CaCl2-induced ileal and colonic LSM contractions in Ca2+-free 80 mM-KCl solution (vs. control). Any ileal and colonic LSM contractions induced by ACh, histamine, PGF2α, and CaCl2 were completely suppressed by verapamil (10-5 M), a voltage-gated/dependent Ca2+ channel (VGCC/VDCC) inhibitor. These findings suggest that DHA and EPA could improve the abnormal contractile functions of the LGI tract associated with inflammatory diseases, partly through inhibition of VGCC/VDCC-dependent ileal and colonic LSM contractions.

Inhibitory Effects of Antipsychotics on the Contractile Response to Acetylcholine in Rat Urinary Bladder Smooth Muscles.

The clinical applications of antipsychotics for symptoms unrelated to schizophrenia, such as behavioral and psychological symptoms, in patients with Alzheimer's disease, and the likelihood of doctors prescribing antipsychotics for elderly people are increasing. In elderly people, drug-induced and aging-associated urinary disorders are likely to occur. The most significant factor causing drug-induced urinary disorders is a decrease in urinary bladder smooth muscle (UBSM) contraction induced by the anticholinergic action of therapeutics. However, the anticholinergic action-associated inhibitory effects of antipsychotics on UBSM contraction have not been sufficiently assessed. In this study, we examined 26 clinically available antipsychotics to determine the extent to which they inhibit acetylcholine (ACh)-induced contraction in rat UBSM to predict the drugs that should not be used by elderly people to avoid urinary disorders. Of the 26 antipsychotics, six (chlorpromazine, levomepromazine (phenothiazines), zotepine (a thiepine), olanzapine, quetiapine, clozapine (multi-acting receptor targeted antipsychotics (MARTAs))) competitively inhibited ACh-induced contractions at concentrations corresponding to clinically significant doses. Further, 11 antipsychotics (perphenazine, fluphenazine, prochlorperazine (phenothiazines), haloperidol, bromperidol, timiperone, spiperone (butyrophenones), pimozide (a diphenylbutylpiperidine), perospirone, blonanserin (serotonin-dopamine antagonists; SDAs), and asenapine (a MARTA)) significantly suppressed ACh-induced contraction; however, suppression occurred at concentrations substantially exceeding clinically achievable blood levels. The remaining nine antipsychotics (pipamperone (a butyrophenone), sulpiride, sultopride, tiapride, nemonapride (benzamides), risperidone, paliperidone (SDAs), aripiprazole, and brexpiprazole (dopamine partial agonists)) did not inhibit ACh-induced contractions at concentrations up to 10-5 M. These findings suggest that chlorpromazine, levomepromazine, zotepine, olanzapine, quetiapine, and clozapine should be avoided by elderly people with urinary disorders.

Docosahexaenoic acid inhibits U46619- and prostaglandin F2α-induced pig coronary and basilar artery contractions by inhibiting prostanoid TP receptors.

Docosahexaenoic acid (DHA, an n-3 polyunsaturated fatty acid) inhibits U46619 (a TP receptor agonist)- and prostaglandin F2α-induced contractions in rat aorta and mesenteric arteries. However, whether these effects could be replicated in vasospasm-prone vessels, such as coronary and cerebral arteries, remains unknown. Here, we evaluated the changes in pig coronary and basilar artery tensions and intracellular Ca2+ concentrations in human prostanoid TP or FP receptor-expressing cells. We aimed to clarify whether DHA inhibits U46619- and prostaglandin F2α-induced contractions in spasm-prone blood vessels and determine if the TP receptor is the primary target for DHA. In both pig coronary and basilar arteries, DHA suppressed U46619- and prostaglandin F2α-induced sustained contractions in a concentration-dependent manner, but did not affect contractions induced by 80 mM KCl. SQ 29,548 (a TP receptor antagonist) suppressed U46619- and prostaglandin F2α-induced contractions by approximately 100% and 60%, respectively. DHA suppressed both U46619- and prostaglandin F2α-induced increases in intracellular Ca2+ concentrations in human TP receptor-expressing cells. However, DHA did not affect prostaglandin F2α-induced increases in intracellular Ca2+ concentrations in human FP receptor-expressing cells. These findings suggest that DHA potently inhibits TP receptor-mediated contractions in pig coronary and basilar arteries, and the primary mechanism underlying its inhibitory effects on arterial contractions involves inhibiting TP receptors.

Transcriptomic changes involved in the dedifferentiation of myofibroblasts derived from the lung of a patient with idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease of unknown etiology. Under pathological conditions in lungs with IPF, myofibroblasts serve a key role in fibrogenesis via the accumulation of an excessive amount of extracellular matrix. To develop effective therapeutic interventions against IPF, studies have recently focused on how to dedifferentiate established myofibroblasts. The present study revealed that JQ1, an inhibitor of bromodomain and extra­terminal proteins, markedly suppressed the expression levels of α­smooth muscle actin and ED­A­fibronectin in myofibroblasts prepared from the lung of a patient with end­stage IPF. Furthermore, these findings were supported by transcriptome analysis using RNA sequencing, in which differentially expressed genes (DEGs) downregulated by JQ1 treatment were significantly enriched in the fibrosis­related signaling pathway. On the other hand, the upregulated DEGs in response to JQ1 treatment were significantly enriched in glutathione metabolism, which may affect the cell status of fibroblast/myofibroblast. To the best of our knowledge, this was the first study to comprehensively analyze transcriptome profiles associated with dedifferentiation of IPF myofibroblasts.

Normetadrenaline and metadrenaline induce rat thoracic aorta/prostate contraction via α1D/1A-adrenoceptor stimulation.

Certain catecholamine metabolites exert significant pharmacological effects. Herein, we evaluated the pharmacological activities of catecholamine metabolites in the rat thoracic aorta, prostate, and spleen to determine whether these metabolites affect the contractile functions of smooth muscle tissue via direct action on α-adrenoceptors and α-adrenoceptor subtypes. Among the catecholamine metabolites examined, normetadrenaline and metadrenaline (10-4 M each) produced relatively strong contractions in the rat thoracic aorta. Maximum aortic contractions induced by normetadrenaline (≈70% of phenylephrine (3 × 10-7 M)-induced contractions) and metadrenaline (≈45%) were significantly smaller than those induced by phenylephrine (≈95%). Normetadrenaline and metadrenaline (10-4 M each) inhibited phenylephrine (3 × 10-7 M)-induced aortic contractions, which were not affected by propranolol (10-6 M), by 5-20%. Normetadrenaline- and metadrenaline (3 × 10-5 M each)-induced aortic contractions were strongly inhibited by prazosin (10-8 M; an α1-adrenoceptor antagonist) and BMY 7378 (10-8-10-7 M; a selective α1D-adrenoceptor antagonist). Metadrenaline (3 × 10-5 M)-induced aortic contractions were also significantly inhibited by silodosin (10-9 M; a selective α1A-adrenoceptor antagonist). Normetadrenaline and metadrenaline (3 × 10-5 M each) caused silodosin (10-9 M)-sensitive prostate contractions but did not cause a prominent spleen contraction. Maximum prostate contractions induced by metadrenaline (≈100% of phenylephrine (3 × 10-5 M)-induced contractions) were nearly identical to those induced by phenylephrine (≈100%) but were significantly larger than those induced by normetadrenaline (≈80%). These findings suggest that normetadrenaline and metadrenaline act as a partial α1D/α1A-adrenoceptor agonist and partial α1D-adrenoceptor/full α1A-adrenoceptor agonist, respectively, functioning as adrenaline system stabilizers in α1D/α1A-adrenoceptor-abundant smooth muscle tissues.