Incomplete inhibition of endothelin-1 pressor effects by an endothelin ETA receptor antagonist

Incomplete inhibition of endothelin-1-induced pressor effects by FR-139317, a novel, potent ET_A receptor antagonist, was observed in conscious, normotensive rats. Maximum inhibition by FR-139317 of the endothelin-1 pressor response (0.1, 0.3, 1.0 nmol/kg) was 49 ± 7, 41± 3, 62 ± 5%, respectively. Two ET_B-selective receptor ligands induced pressor responses in conscious rats. A portion of the endothelin-1 pressor response may be mediated by ET_B receptors, and ET_B-mediated vasoconstriction may contribute to incomplete inhibition of the pressor response to endothelin-1 by an ET_A-selective receptor antagonist.     

Involvement of tyrosine phosphorylation in endothelin-1-induced calcium-sensitization in rat small mesenteric arteries

1. We have studied the effect of endothelin-1 stimulation on protein tyrosine phosphorylation levels in intact small mesenteric arteries of the rat and investigated the effects of tyrosine kinase inhibition on the contractile response to this agonist.
2. Endothelin-1 stimulated a rapid (20 s), sustained (up to 20 min) and concentration-dependent (1–100 nM) increase in protein tyrosine phosphorylation levels which coincided temporally with the contractile response in intact and α-toxin permeabilized small artery preparations. Tyrosine phosphorylation was increased in four main clusters of proteins of apparent molecular mass 28–33, 56–61, 75–85 and 105–115 kDa. Endothelin-1-induced protein tyrosine phosphorylation was independent of extracellular calcium, antagonized by the tyrosine kinase inhibitor tyrphostin A23 but not by the inactive tyrphostin A1.
3. In intact small arteries tyrphostin A23 inhibited the force developed to endothelin-1 at all concentrations studied; at higher concentrations (10 and 100 nM) the profile of contraction was altered from a sustained to a transient response. Tyrphostin A1 inhibited the contractile response to endothelin-1 at all concentrations except 100 nM; the profile of the response was not altered. Neither tyrphostin affected the transient phasic contraction induced by endothelin-1 (100 nM) in the absence of extracellular calcium.
4. In rat α-toxin permeabilized mesenteric arteries endothelin-1 caused a concentration-dependent increase in force in the presence of 10 μM GTP and low (pCa 6.7) constant calcium, demonstrating increased sensitivity of the contractile apparatus to calcium. Tyrphostin A23 inhibited this response by approximately 50%, tyrphostin A1 did not affect endothelin-1-induced calcium sensitization of force.
5. We conclude that increased tyrosine phosphorylation is important in the contractile response induced by endothelin-1 in intact small mesenteric arteries. Furthermore our data implicate activation of this signalling pathway in the tonic phase of contraction possibly through modulation of the sensitivity of the contractile apparatus to calcium.

     

Role of endogenous endothelin-1 in post-ischemic cardiac dysfunction and norepinephrine overflow in rat hearts

Endothelin-1 and norepinephrine are involved in myocardial ischemia/reperfusion injury. The aim of this study was to investigate the role of endogenously generated endothelin-1 in ischemia/reperfusion-induced norepinephrine overflow and cardiac dysfunction using a nonselective prototype of endothelin-converting enzyme (ECE) inhibitor, phosphoramidon, and a selective ECE inhibitor, SM-19712 (4-chloro-N-[[(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-yl)amino]carbonyl]benzenesulfonamide, monosodium salt). According to the Langendorff technique, isolated Sprague-Dawley rat hearts were subjected to 40-min global ischemia followed by 30-min reperfusion. Phosphoramidon and SM-19712 were perfused 30 min before ischemia and during reperfusion. Endothelin-1 level in left ventricle was increased by ischemia/reperfusion. This increase in left ventricular endothelin-1 level was suppressed by treatment with SM-19712. SM-19712 significantly improved ischemia/reperfusion-induced cardiac dysfunction such as decreased left ventricular developed pressure and dP/dt(max) and increased left ventricular end diastolic pressure. In addition, this agent suppressed excessive norepinephrine overflow in the coronary effluent from the post-ischemic heart. In contrast, treatment with phosphoramidon further enhanced left ventricular endothelin-1 level and norepinephrine overflow, and significantly worsened cardiac dysfunction after ischemia/reperfusion. These responses such as exaggerated norepinephrine overflow and the cardiac dysfunction observed after ischemia/reperfusion were markedly suppressed in the presence of a selective endothelin ET(A) receptor antagonist, ABT-627 [2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N,N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid]. These findings indicate that cardiac endothelin-1 production is enhanced by ischemia/reperfusion, and this endogenously increased endothelin-1 is involved in post-ischemic norepinephrine overflow and cardiac dysfunction via the activation of endothelin ET(A) receptors.     

Characterisation of the endothelin receptor mediating contraction of human pulmonary artery using BQ123 and Ro 46-2005

We have characterised the endothelin receptor mediating contraction of human isolated pulmonary artery. Endothelin-induced a concentration-dependent contraction of human endothelium-denuded pulmonary artery (EC₅₀ 5.6 nM). In contrast, endothelin-3 produced only a small contraction (≈ 12% of maximum endothelin-1 response) at the highest concentration tested (1 μM). The ET_B receptor-selective agonist, sarafotoxin S6c (0.1 nM to 1 μM) did not cause contraction of human pulmonary artery. Pretreatment of human pulmonary artery with BQ123 (1–10 μM), an ET_A receptor-selective blocking drug, resulted in a concentration-dependent, surmountable antagonism of endothelin-1-induced contractions (apparent pK_B 6.6–7.0). Schild analyses yielded a shallow slope (0.58), which was significantly less than unity and, consequently, the calculated pA₂ (8.1) was greater than the individual pK_B values. Pretreatment of human pulmonary artery with Ro 46-2005 (30 μM), a non-peptide, non-selective endothelin receptor-blocking drug, resulted in a surmountable antagonism of endothelin-1-induced contractions (apparent pK_B 5.5). In conclusion, endothelin-1-induced contraction of human pulmonary artery appears to be mediated predominantly via ET_A receptors, although the shallow Schild slope observed with BQ123 indicates possible receptor heterogeneity.     

Protein kinase C inhibitors decrease endothelin ET(B) receptor mRNA expression and contraction during organ culture of rat mesenteric artery

The effect of protein kinase C (PKC) inhibitors on the induction of endothelin ET(B) receptors during organ culture was examined in isolated segments of the rat mesenteric artery. After 24 h of organ culture, the endothelin ET(B) receptor agonist sarafotoxin 6c (S6c) induced a strong contraction compared to fresh segments. The contractile response after 24-h organ culture to S6c was studied in presence (30-min preincubation) or absence, after 24-h treatment, of the PKC inhibitors staurosporine, K252a and Ro31-7549. Exposure to staurosporine or K252a in presence and after 24-h treatment reduced the S6c contraction. In contrast, presence of 2-1[1-3(aminopropyl)indol-3-yl]-3(1-methyl-1H-indol-3-yl)maleimide (Ro31-7549), did not affect the S6c-induced contraction, whereas 24-h treatment abolished the increase of contraction. The PKA inhibitor N-(2-[bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide (H89) did not affect the S6c responses. The mRNA expressions of endothelin ET(B) receptors (analysed with real-time PCR) were abolished after 24-h treatment with the PKC inhibitors. These results suggest that PKC is involved in the endothelin ET(B) receptor upregulation following organ culture.     

Endothelin-1 and endothelin-2 initiate and maintain contractile responses by different mechanisms in rat mesenteric and cerebral arteries

BACKGROUND AND PURPOSE

Endothelin (ET)-1 and ET-2 cause potent long-lasting vasoconstrictions by tight binding to smooth muscle ET_A receptors. We tested the hypotheses that different mechanisms mediate initiation and maintenance of arterial contractile responses to ET-1 and ET-2 and that this differs among vascular beds.

EXPERIMENTAL APPROACH

Segments of rat mesenteric resistance artery (MRA) and basilar artery (BA) were studied in wire myographs with and without functional antagonists.

KEY RESULTS

Sensitivity and maximum of MRA contractile responses to ET-1 were not, or only moderately, reduced by stimulation of soluble GC, AC or K⁺-channels and by an inhibitor of receptor-operated ion channels. However, each of these reduced maintenance of ET-1 effects and relaxed ET-1-induced contractions in MRA. A calcium channel antagonist did not alter sensitivity, maximum and maintenance of ET-1 effects, but relaxed ET-1-induced contractions in MRA. A PLC inhibitor prevented contractile responses to ET-1 and ET-2 in MRA and BA, and relaxed ET-1- and ET-2-induced responses in MRA and ET-1 effects in BA. A Rho-kinase inhibitor did not modify sensitivity, maximum and maintenance of responses to both peptides in both arteries but relaxed ET-2, but not ET-1, effects in MRA and ET-1 effects in BA.

CONCLUSIONS AND IMPLICATIONS

PLC played a key role in arterial contractile responses to ETs, but ET-1 and ET-2 initiated and maintained vasoconstriction through different mechanisms, and these differed between MRA and BA. Selective functional antagonism may be considered for agonist- and vascular bed selective pharmacotherapy of ET-related diseases.     

Mechanisms underlying diabetes enhancement of endothelin-1-induced contraction in rabbit basilar artery

The influence of alloxan-induced diabetes on the reactivity of rabbit basilar artery to endothelin-1 was examined. Endothelin-1 induced concentration-dependent contraction of basilar arteries that was higher in diabetic than in control rabbits. Endothelium removal produced a higher enhancement of the endothelin-1-induced contraction in control than in diabetic rabbits. N(G)-nitro-L-arginine (L-NOArg) enhanced the maximal contraction induced by endothelin-1 in control rabbits and potentiated this response in diabetic rabbits. Endothelin ETA receptor antagonist, cyclo(D-Asp-Pro-D-Val-Leu-D-Trp) (BQ-123), inhibited endothelin-1-induced contraction in both rabbit groups. Endothelin ETB receptor antagonist, 2,6-Dimethylpiperidinecarbonyl-gamma-Methyl-Leu-Nin-(Methoxycarbonyl)-D-Trp-D-Nle (BQ-788), enhanced endothelin-1-induced contraction in control rabbits and decreased the potency of endothelin-1 in diabetic rabbits. Sodium nitroprusside-induced relaxation of basilar arteries was lower in diabetic than in control rabbits. These results suggest that mechanisms underlying rabbit basilar artery hyperreactivity to endothelin-1 include decreased endothelial modulation of endothelin-1-induced contraction, with impaired endothelial endothelin ETB receptor activity; decreased sensitivity to nitric oxide (NO) in vascular smooth muscle; and enhanced participation of muscular endothelin ETA and ETB receptors.     

Different role of endothelin ETA and ETB receptors and endothelial modulators in diabetes-induced hyperreactivity of the rabbit carotid artery to endothelin-1

The influence of diabetes on regulatory mechanisms and specific receptors implicated in the contractile response of isolated rabbit carotid arteries to endothelin-1 was examined. Endothelin-1 induced a concentration-dependent contraction that was greater in arteries from diabetic rabbits than in arteries from control rabbits. Endothelium removal or N(G)-nitro-L-arginine enhanced contractions in response to endothelin-1 only in control arteries, without modifying the endothelin-1 response in diabetic arteries. Indomethacin, furegrelate (thromboxane A(2) inhibitor), or cyclo-(D-Asp-Pro-D-Val-Leu-D-Trp) (BQ-123; endothelin ET(A) receptor antagonist) inhibited the contractions in response to endothelin-1, the inhibition being greater in diabetic arteries than in control arteries. 2,6-Dimethylpiperidinecarbonyl-gamma-methyl-Leu-N(in)-(methoxycarbonyl)-D-Trp-D-Nle (BQ-788; endothelin ET(B) receptor antagonist) enhanced the contraction elicited by endothelin-1 in control arteries and displaced to the right the contractile curve for endothelin-1 in diabetic arteries. In summary, diabetes induces hyperreactivity of the rabbit carotid artery to endothelin-1 by a mechanism that at least includes: (1) enhanced activity of muscular endothelin ET(A) receptors; (2) impairment of endothelin ET(B) receptor-mediated nitric oxide (NO) release; and (3) enhancement of the production of thromboxane A(2).     

Role of endothelin ET(B) receptors in the renal hemodynamic and excretory responses to big endothelin-1

We determined the role of endothelin ET(B) receptor in the renal hemodynamic and excretory responses to big endothelin-1, using A-192621, a selective endothelin ET(B) receptor antagonist and the spotting-lethal (sl) rat, which carries a naturally occurring deletion in the endothelin ET(B) receptor gene. An intravenous injection of big endothelin-1 produced a hypertensive effect, which is greater in wild-type (+/+) rats pretreated with A-192621 and in homozygous (sl/sl) rats. Big endothelin-1 markedly increased urine flow, urinary excretion of sodium and fractional excretion of sodium in wild-type rats treated with the vehicle. These excretory responses to big endothelin-1 were markedly reduced by pharmacological endothelin ET(B) receptor blockade. On the other hand, big endothelin-1 injection to the endothelin ET(B) receptor-deficient homozygous animals resulted in a small diuretic effect. When renal perfusion pressure was protected from big endothelin-1-induced hypertension by an aortic clamp, the excretory responses in vehicle-treated wild-type rats were markedly attenuated. In homozygous or A-192621-treated wild-type rats, there was a small but significant decreasing effect in urine flow. In addition, big endothelin-1 significantly elevated nitric oxide (NO) metabolite production in the kidney of wild-type rats but not in the homozygous rats. We suggest that the diuretic and natriuretic responses to big endothelin-1 consist of pressure-dependent and pressure-independent effects and that the increased NO production via the activation of endothelin ET(B) receptors in the kidney is closely related to the big endothelin-1-induced excretory responses.     

Transforming growth factor-beta1 stimulates heme oxygenase-1 expression via the PI3K/Akt and NF-kappaB pathways in human lung epithelial cells

A previous report showed that transforming growth factor-β1 (TGF-β1) can induce heme oxygenase-1 (HO-1) expression, attenuate cellular injury, and maintain tissue homeostasis. In this study, we investigated the involvement of phosphoinositide-3-OH-kinase (PI3K)/Akt and the nuclear factor-κB (NF-κB) signaling pathway in TGF-β1-induced HO-1 expression in human lung epithelial cells (A549). Treatment of A549 cells with TGF-β1 caused HO-1 to be expressed in a concentration- and time-dependent manner. Treatment of A549 cells with LY 294002 (2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, a PI3K inhibitor), an Akt inhibitor, and the dominant negative mutant of Akt (Akt DN) inhibited TGF-β1-induced HO-1 expression and HO-1-luciferase activity. Stimulation of cells with TGF-β1 caused an increase in Akt phosphorylation in a time-dependent manner, which was inhibited by wortmannin and LY 294002 (PI3K inhibitors). In addition, treatment of A549 cells with Bay 117082 ((E)-3-[4-methylphenylsulfonyl]-2-propenenitrile, an IκB phosphorylation inhibitor), pyrrolidine dithiocarbamate (PDTC, an NF-κB inhibitor), and the dominant negative mutant of IκB (IκBM) inhibited TGF-β1-induced HO-1 expression and HO-1-luciferase activity. Treatment of A549 cells with TGF-β1-induced IκB kinase /β (IKK/β) phosphorylation, IκB phosphorylation, IκB degradation, p65 Ser536 phosphorylation, and κB-luciferase activity. The TGF-β1-mediated increases in IKK/β phosphorylation, p65 Ser536 phosphorylation, and κB-luciferase activity were inhibited by LY 294002, an Akt inhibitor, and Akt DN. Taken together, these results suggest that the PI3K/Akt dependent IKK/β/NF-κB signaling pathway plays an important role in TGF-β1-induced HO-1 expression in A549 cells.     

Activation of endothelin ETA receptors masks the constrictor role of endothelin ETB receptors in rat isolated small mesenteric arteries

1. Endothelin-1 (ET-1) produces constriction of the rat mesenteric vascular bed in vivo via ET_A and ET_B receptor subtypes. The aim of this study was to investigate the relative roles of these receptor subtypes in rat isolated, endothelium-denuded, small mesenteric arteries, under pressure, by use of ET-1; the ET_A receptor antagonist, BQ-123; the ET_B receptor selective agonist, sarafotoxin S6c (SRTX S6c); the ET_B receptor selective antagonist, BQ-788; and the ET_A/ET_B antagonist, TAK-044.
2. In 3rd generation mesenteric arteries, ET-1 (10⁻¹³10⁻⁷ M) produced concentration-dependent contractions (pD₂ 9.86). SRTX S6c (10⁻¹²10⁻⁷ M) also induced concentration-dependent contractions in 53% of arteries studied, although the E_max was much less than that obtained with ET-1 (10.7±2.9% vs 101.9±2.6% of the 60 mM KCl-induced contraction).
3. Neither ET_B receptor desensitization, by a supra-maximal concentration of SRTX S6c (10⁻⁷ M), nor incubation with BQ-788 (3×10⁻⁸ M), had any significant effect on the ET-1 concentration-response curve, although both treatments tended to enhance rather than inhibit responses to ET-1.
4. In the presence of BQ-123 (10⁻⁶ M), responses to low concentrations of ET-1 (up to 10⁻¹⁰ M) were unaffected but responses to concentrations of ET-1 above 10⁻¹⁰ M were significantly inhibited.
5. SRTX S6c desensitization followed by incubation with BQ-123 (10⁻⁶ M) or co-incubation with BQ-788 (3×10⁻⁸ M) and BQ-123 caused inhibition of responses to all concentrations of ET-1, resulting in a rightward shift of the ET-1 concentration-response curve. The same effect was obtained by incubation with TAK-044 (10⁻⁸ M and 3×10⁻⁷ M).
6. Thus, responses of rat small mesenteric arteries to ET-1 are mediated by both ET_A and ET_B receptors. The relative role of ET_B receptors is greater than that predicted by the small responses to SRTX S6c or by resistance of ET-1-induced contraction to ET_B receptor desensitization or BQ-788. The effect of ET_B receptor desensitization or blockade is only revealed in the presence of ET_A receptor blockade, suggesting the presence of a ‘crosstalk'' mechanism between the receptors. These results support the concept that dual receptor antagonists, like TAK-044, may be required to inhibit completely constrictor responses to ET-1.

     

In vitro and in vivo effects of endothelin-1 and YM598, a selective endothelin ET A receptor antagonist, on the lower urinary tract

We investigated the contractile response of the lower urinary tract to endothelin-1 in vitro (rabbits) and in vivo (dogs). We also assessed the effects of a selective endothelin ET_A receptor antagonist, (E)-N-[6-methoxy-5-(2-methoxyphenoxy)[2, 2′-bipyrimidin]-4-yl]-2-phenylethenesulfonamide monopotassium salt (YM598), on endothelin-1-induced contractile responses. In the in vitro study, endothelin-1 induced contractile responses in isolated rabbit bladder base, urethra, and prostate tissues. YM598 (10^− 7–10^− 5 M) antagonized these endothelin-1-induced contractile responses without affecting the maximal responses. In the in vivo study, endothelin-1 induced the elevation of non-prostatic urethral pressure as well as prostatic urethral pressure even in the presence of tamsulosin (10 μg/kg, i.v.) in anesthetized male dogs. YM598 (0.1–3 mg/kg, i.v.) inhibited these endothelin-1-induced contractile responses in a dose-dependent fashion. These results suggest that endothelin ET_A receptors play an important role in the lower urinary tract contraction, and that the selective endothelin ET_A receptor antagonist YM598 has ameliorating effects on various urinary dysfunctions, including benign prostatic hyperplasia.     

Involvement of RhoA/ROCK in myocardial fibrosis in a rat model of type 2 diabetes

Aim:

To investigate whether activation of RhoA/Rho kinase (ROCK) is involved in myocardial fibrosis in diabetic hearts.

Methods:

A rat model of type 2 diabetes was established using high fat diet combined with streptozotocin (30 mg/kg, ip). Animals were randomly divided into 3 groups: control rats, untreated diabetic rats that received vehicle and treated diabetic rats that received Rho-kinase inhibitor fasudil hydrochloride hydrate (10 mg·kg^-1·d^-1, ip, for 14 weeks). Cardiac contractile function was evaluated in vivo. The morphological features of cardiac fibrosis were observed using immunohistochemistry and TEM. The mRNA expression of JNK, TGFβ1, type-I, and type-III procollagen was assessed with RT-PCR. The phosphorylation of MYPT1, JNK and Smad2/3, as well as the protein levels of TGFβ1 and c-Jun, were evaluated using Western blotting.

Results:

In untreated diabetic rats, myocardial fibrosis was developed and the heart contractility was significantly reduced as compared to the control rats. In the hearts of untreated diabetic rats, the mRNA expression level and activity of JNK were upregulated; the expression of TGFβ1 and phosphorylation of Smad2/3 were increased. In the hearts of treated diabetic rat, activation of JNK and TGFβ/Smad was significantly decreased, myocardial fibrosis was reduced, and cardiac contractile function improved.

Conclusion:

The data suggest that fasudil hydrochloride hydrate ameliorates myocardial fibrosis in rats with type 2 diabetes at least in part through inhibiting the JNK and TGFβ/Smad pathways. Inhibition of RhoA/ROCK may be a novel therapeutic target for prevention of diabetic cardiomyopathy.     

ERK1/2通路参与大鼠肠系膜动脉平滑肌细胞ETB受体上调表达

目的探讨细胞外信号调节激酶1/2(ERK1/2)信号转导通路在血管平滑肌细胞内皮素-1 B型受体(ET_B)上调中的作用。方法用大鼠肠系膜上动脉离体培养模型，以敏感的离体小血管张力描记技术记录血管张力变化，实时PCR定量ET_B受体mRNA，PhosphoELISA法测定细胞内磷酸化的ERK1/2蛋白水平。结果大鼠肠系膜上动脉培养3 h，细胞内ERK1/2蛋白磷酸化水平明显增高，培养24 h ET_B受体mRNA表达水平显著上调，选择性ET_B受体激动剂蛇毒类似物(sarafotoxin 6c，S6c)引起的收缩增强；与特异性ERK1/2通路阻滞剂SB386023共同孵育24 h，S6c引起的最大收缩E_max明显下降，ET_B受体mRNA水平也显著降低。结论ERK1/2信号转导通路参与大鼠肠系膜上动脉离体平滑肌细胞ET_B受体上调过程。     

Desensitization of endothelial P2Y1 receptors by PKC-dependent mechanisms in pressurized rat small mesenteric arteries

Background and purpose:

Extracellular nucleotides play a crucial role in the regulation of vascular tone and blood flow. Stimulation of endothelial cell P2Y1 receptors evokes concentration-dependent full dilatation of resistance arteries. However, this GPCR can desensitize upon prolonged exposure to the agonist. Our aim was to determine the extent and nature of P2Y1 desensitization in isolated and pressurized rat small mesenteric arteries.

Experimental approach:

The non-hydrolyzable selective P2Y1 agonist ADPβS (3 µM) was perfused through the lumen of arteries pressurized to 70 mmHg. Changes in arterial diameter and endothelial cell [Ca²⁺]_i were obtained in the presence and absence of inhibitors of protein kinase C (PKC).

Key results:

ADPβS evoked rapid dilatation to the maximum arterial diameter but faded over time to a much-reduced plateau closer to 35% dilatation. This appeared to be due to desensitization of the P2Y1 receptor, as subsequent endothelium-dependent dilatation to acetylcholine (1 µM) remained unaffected. Luminal treatment with the PKC inhibitors BIS-I (1 µM) or BIS-VIII (1 µM) tended to augment concentration-dependent dilatation to ADPβS (0.1–3 µM) and prevented desensitization. Another PKC inhibitor, Gö 6976 (1 µM), was less effective in preventing desensitization. Measurements of endothelial cell [Ca²⁺]_i in pressurized arteries confirmed the P2Y1 receptor but not M₃ muscarinic receptor desensitization.

Conclusions and implications:

These data demonstrate for the first time the involvement of PKC in the desensitization of endothelial P2Y1 receptors in pressurized rat mesenteric arteries, which may have important implications in the control of blood flow by circulating nucleotides.     

γ-分泌酶抑制剂在肺纤维化上皮间质转化中的作用

目的 检测体外转化生长因子（TGF）-β1诱导肺纤维化上皮间质转化（EMT）的形成情况并检测Notch信号特异性抑制剂γ-分泌酶抑制剂（DAPT）对其影响及可能机制。方法 将A549细胞分成对照组（RPMI 1640完全培养基培养）、TGF-β1组（在含有10 μg/L TGF-β1的RPMI 1640培养基中培养）、TGF-β1+DAPT组（在含有10 μg/L TGF-β1和2 μmol DAPT的RPMI 1640培养基中培养）、DAPT组（在含有2 μmol DAPT的RPMI 1640培养基中培养）。通过倒置显微镜观察细胞形态,实时荧光定量逆转录聚合酶链反应检测肺泡上皮细胞特异性蛋白E-钙黏合素以及间质细胞特异性蛋白α-肌动蛋白（α-SMA）mRNA相对表达水平,Western blot检测E-钙黏合素以及α-SMA蛋白表达水平。结果 倒置显微镜检查示,对照组细胞呈多边形,铺路石样,细胞间连接紧密;TGF-β1组细胞呈梭行,纺锤状,细胞间连接减少;TGF-β1+DAPT组仅有少量细胞呈梭形,多数细胞形态与对照组相似;DAPT组细胞形态大致同对照组。与对照组相比,TGF-β1组α-SMA蛋白及mRNA表达增加,而E-钙黏合素蛋白及mRNA表达减弱（P<0.05）;与TGF-β1组比较,TGF-β1+DAPT组α-SMA蛋白及mRNA表达水平降低,而E-钙黏合素蛋白及mRNA表达水平增加（P<0.05）;DAPT组与对照组2指标的蛋白与mRNA相对表达水平差异无统计学意义（P>0.05）。结论 TGF-β1可诱导肺上皮间质转化,而Notch信号抑制剂DAPT能够阻断、部分或全部逆转这一过程。     

α1-Adrenoceptors mediate the responses to BHT-920 and rauwolscine in dog mesenteric artery after partial depolarization by KCl

In normal (5 mM KCl) HEPES buffer solution, BHT-920 and rauwloscine did not produce any contractile responses in dog mesenleric artery strips. However, when the preparation was bathed in 20 mM KCl HEPES buffer solution, BHT-920 and rauwloscine evoked significant contractile responses. These effects were markedly inhibited by parazosin which caused a parallel shift to the right of the concentration-response curve to BHT-920. In ¹⁵Ca uptake experiments carried out in the 20 mM KCl HEPES buffer solution BHT-920 and rauwolscine significantly increased ⁴⁵Ca influxes which were reduced by prazosin. These results suggest that postsynaptic α₁-adrenoceptors in dog mesenteric artery mediate the contractile responses and the ⁴⁵Ca influxes induced by BHT-920 and rauwloscine after partial depolarization by 20 mM KCl.     

Vascular alpha1-adrenoceptors in isolated perfused rat kidney: influence of ageing

1. The present study identifies alpha1-adrenoceptor subtype(s) involved in constrictor responses of the kidney and how ageing influences it. 2. The study was conducted on kidneys from F344BNF1 rats, which unlike F344 or Wistar rats used by many previous investigators do not exhibit glomerulonephritis at advanced age. 3. Noradrenaline (NA) and phenylephrine (PHE) (non-selective alpha1) and A61063 (selective alpha(1A)) adrenoceptor agonists elicited constriction of perfused kidneys of young and old rats. The pD2 values (index of renovascular reactivity) were significantly higher for A61603 than for either PHE or NA, and significantly decrease across age groups. 4. BMY 7378 or RS 100329, alpha(1D)- or alpha(1A)-adrenoceptor antagonists, respectively antagonized the constrictor responses and suppressed the maximal responses to all agonists in young adult rat kidneys. However, antagonism of PHE or A61063 by BMY 7378 in old rat kidneys was surmountable. 5. This study suggests that: (i) alpha(1A) and alpha(1D)-adrenoceptor subtypes mediate vasoconstriction of perfused rat kidney; (ii) alpha(1A)-adrenoceptor subtype appears to predominate in renal vasculature based on agonist relative potencies. (iii) Ageing significantly decreases alpha1-adrenoceptor-mediated vasoconstriction of rat kidney.     

槲皮素-3-O-芹菜糖基芦丁糖苷对新生大鼠海马神经前体细胞增殖的影响

目的探讨一种新型抗抑郁剂槲皮素-3-O-芹菜糖基芦丁糖苷(代号:CTN-986)对神经前体细胞增殖的影响。方法分离培养新生大鼠海马神经前体细胞,运用免疫细胞化学的方法对所培养的细胞特性进行鉴定。用MTT法和3H-胸腺嘧啶核苷参入法分别观察CTN-986对新生大鼠海马神经前体细胞增殖的影响,并初步探讨其作用机制。结果所培养的细胞具有神经前体细胞的特性,药物研究发现,氟西汀和CTN-986(2~250μmol.L-1)作用4 d,可以促进神经前体细胞的增殖;同时给予5-HT1A受体特异性拮抗剂WAY-100635(0.1μmol.L-1)可以对抗CTN-986诱导的促神经前体细胞的增殖。结论CTN-986可以促进海马神经前体细胞的增殖,并且该作用的发挥与激活5-HT1A受体关系密切。