ATP-induced endothelium-independent enhancement of lymphatic vasomotion in guinea-pig mesentery involves P2X and P2Y receptors

1. The present study has investigated mechanisms underlying ATP-induced endothelium-independent enhancement of vasomotion in guinea-pig mesenteric lymphatic vessels. 2. Lymphatic vasomotion, vessel tone and smooth muscle [Ca(2+)](i) showed similar ATP concentration-response curves. 3. ATP, at 0.1 mM, caused a biphasic increase in tonic [Ca(2+)](i) and superimposed vasomotion-associated Ca(2+) transients. All ATP-induced [Ca(2+)](i) changes were abolished by incubating the smooth muscle with suramin (0.1 mM). 4. alpha,beta-MeATP (0.1 mM) and UTP (0.1 mM) caused similar changes in [Ca(2+)](i) but the responses to these agonists were smaller than to ATP. 5. The actions of alpha,beta-MeATP (0.1 mM) were inhibited by suramin (0.1 mM) and PPADS (30 micro M) but not by reactive blue 2 (30 micro M). 6. In the presence of alpha,beta-MeATP (0.1 mM), the increases in tonic [Ca(2+)](i) and vasomotion-associated Ca(2+) transients induced by ATP (0.1 mM) were inhibited by U73122 (5 micro M), CPA (20 micro M) and heparin, whereas U73343 (5 micro M) and pre-treatment with PTx (100 ng ml(-1)) had no significant effects. 7. Depletion of the intracellular stores with CPA (20 micro M) caused an increase in [Ca(2+)](i), which was not blocked by desensitization of P(2X) receptors with alpha,beta-MeATP. 8. The data indicate that ATP, at relatively high concentrations increases lymphatic smooth muscle [Ca(2+)](i) and vasomotion through activation of P(2X1) and P(2Y2) purinoceptors present on lymphatic smooth muscle. The increase in [Ca(2+)](i) is likely to result from Ca(2+) release from inositol-1,4,5-trisphosphate-sensitive stores as well as Ca(2+) influx through store-operated channels and P(2X)-gated channels.     

Effects of histamine on the contractile and electrical activity in isolated lymphatic vessels of the guinea-pig mesentery

1 The effect of histamine on the rate of lymphatic vessel constrictions and lymphatic smooth muscle membrane potential was examined in the guinea-pig mesentery. 2 Histamine (0.01-5 micro M) increased the frequency and decreased the amplitude of constrictions in lymphatic vessels under intraluminal perfusion. This response was accompanied by a depolarization of the smooth muscle membrane potential, an increase in the activity of spontaneous transient depolarizations (STDs), the proposed pacemaker for constrictions in these vessels, and an increase in the occurrence of action potentials. 3 Responses to histamine were inhibited by the H(1) receptor antagonist pyrilamine (0.2 micro M), but unaffected by NO synthase inhibition with N(G)-nitro L-arginine (L-NOARG, 100 micro M) and lysis of the endothelium. 4 In about 50% of the vessels, a decrease in constriction frequency, STD activity and a smooth muscle hyperpolarization were observed in response to dimaprit (10 micro M), suggesting the presence of H(2) receptors. These vessels had also a significantly lower basal contractile rate. Lymphatic vessel pumping was not affected by R-alpha-methylhistamine (10-50 micro M), ruling out a role for H(3) receptor stimulation in the histamine response. 5 The present results suggest a direct action of histamine on the lymphatic smooth muscle via stimulation of H(1) (and in some vessels H(2)) receptors. H(1) receptors enhance and H(2) receptors slow down lymphatic pumping, the dominant effect being an increased contractile activity. Correlation of these effects with histamine-induced changes in membrane potential and STD activity suggests the involvement of these electrical changes in the initiation of the contractile response.     

5-HT decreases contractile and electrical activities in lymphatic vessels of the guinea-pig mesentery: role of 5-HT 7-receptors

1 Constriction measurements and intracellular microelectrode recordings were performed in vitro on lymphatic vessels isolated from the guinea-pig mesentery to investigate whether 5-hydroxytryptamine (5-HT) affected lymphatic pumping and smooth muscle membrane potential. 2 5-HT decreased in a concentration-dependent manner the frequency of constrictions induced by intraluminal vessel perfusion. In nonperfused vessels, 5-HT hyperpolarized the lymphatic smooth muscle membrane potential and decreased the frequency and amplitude of spontaneous transient depolarizations (STDs). 3 The actions of 5-HT were significantly reversed by the 5-HT(7) receptor antagonist (2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]pyrrolidine (SB269970, 0.5 micro M) and by the 5-HT(1/2/5/7) receptor antagonists methysergide (0.5 micro M), and were mimicked by the 5-HT(1/7)-receptor agonist, 5-CT. 4 The 5-HT(4)-receptor antagonists 1-methyl-1H-indole-3-carboxylic acid [1-2-[(methyl sulfonyl) amino] ethyl-4-piperidinyl] methyl ester (GR113808, 1 micro M) and (1-piperidinyl) ethyl 1H-indole 3-carboxylate (SB203186, 1 micro M) did not significantly affect the 5-HT-induced responses. The 5-HT(4)-receptor agonist 1-(4-amino-5-chloro-2-methoxy-phenyl)-3-[1-(2-methylsulfonylamino) ethyl-4-piperidinyl]-1-propanone hydrochloride (RS67506) decreased the constriction frequency, albeit only at 50 micro M and without affecting the smooth muscle membrane potential. 5 Responses to 5-HT were attenuated by the nitric oxide synthase inhibitor N(G)-nitro L-arginine (100 micro M), whereas indomethacin (10 micro M) and tetrodotoxin (1 micro M) were without effects. 6 5-HT-induced responses were inhibited by the ATP-sensitive K(+) channel blocker, glibenclamide (10 micro M) and the cAMP-dependent protein kinase inhibitor N-[2-(p-bromociannamylamino)-ethyl]-5-isoquinolinesulfonamide-dichloride (H89, 10 micro M) blocked the hyperpolarization. 7 These results suggest that 5-HT modulates the rate of lymphatic vessel pumping by eliciting K(ATP) channel-mediated smooth muscle hyperpolarization and decrease in STD activity, which appear to be mediated by activation of 5-HT(7) receptors coupled to cAMP production.     

Endothelin-1 induces potent constriction of lymphatic vessels in situ

The response of lymph vessels, arterioles and venules in the exteriorized rat mesentery to endothelin-1, vasopressin and norepinephrine was examined with the aid of high-resolution television microscopy. On a molar basis, endothelin-1 was more potent than vasopressin to contract the three types of vessels. Norepinephrine, which could constrict blood microvessels, did not act on lymph vessels. Acetylcholine, sodium-nitroprusside and isoproterenol were ineffective to block the constrictive responses of lymph vessels to endothelin-1 and vasopressin. At the same concentrations, however, acetylcholine and sodium-nitroprusside antagonized the responses of arterioles and venules to endothelin-1 and norepinephrine, whereas the responses of blood microvessels to vasopressin remained unaffected. Isoproterenol, at doses capable of blocking the response of the arterioles and venules to norepinephrine, did not interfere with the constriction induced by endothelin-1 and vasopressin on these vessels. It is suggested that endothelin-1 might play a role in the regulation of lymphatic contractility apart from its vasoconstrictor activity on blood vessels.     

Development of lymphatic vessels: tumour lymphangiogenesis and lymphatic invasion

In human solid cancer, the lymph node status is the most important prognostic indicator for the clinical outcome of patients. Follow-up data has shown that about 80% of metastasis follows an orderly pattern of progression via the lymphatic network while about 20% systemic metastasis occurs, bypassing the lymphatic system. Over the past few years, advances have been made in understanding the cellular and molecular aspects of physiological lymphangiogenesis and tumour-induced lymphangiogenesis, and the majority of studies point out to a positive correlation between tumour-induced lymphangiogenesis and lymphatic metastasis. However, the impact of intra- and peritumoural lymphatics on the tumour biology and the first steps of lymphatic metastasis, i.e. the invasion of tumour cells into the lymphatic vessels, are not well understood. We will give an outline of i. the physiological process of lymphangiogenesis, ii. tumour-induced lymphangiogenesis and lymphatic metastasis, iii. lymphatic invasion and the common pathways of tumour-lymphangiogenesis and lymphatic invasion. The growing interest in this topic has brought up a number of new molecular players in the field, which may provide the basis for a rational therapy against the process of lymphatic dissemination of tumour cells.     

尼莫地平对蛛网膜下腔出血后脑血管痉挛模型兔血浆BNP和ET-1表达水平的影响

目的探讨尼莫地平（ND）对蛛网膜下腔出血（SAH）后脑血管痉挛（CVS）兔血浆脑利钠肽（BNP）和内皮素-1（ET-1）含量的影响。方法采用枕大池二次注血法建立兔CVS模型。将40只成年日本大耳白兔随机均分为单纯SAH组（SAH组）和ND治疗组（ND组）。观察两组实验动物的食量及神经功能评分,分别采用酶联免疫吸附测定法（ELISA）和放射免疫法（R IA）检测血浆BNP、ET-1含量,并用经颅多普勒超声（TCD）动态观察两组家兔术前1天和术后第1、4、7、10、14天的基底动脉（BA）血流速度。结果两组家兔注血后第1天血浆BNP水平开始升高（P〈0.05）,ET-1虽较术前有所升高但无统计学意义（P〉0.05）,4-7 d BNP、ET-1均达到高峰（P〈0.05-0.01）,且随着时间的推移有逐渐降低的趋势;ND组BNP及ET-1含量增加的程度明显低于SAH组（P〈0.05-0.01）,但仍显著高于术前对照组（P〈0.05）;两组家兔术后BA血流速度的动态变化趋势与其血浆BNP、ET-1的变化基本一致。结论 SAH后血浆BNP、ET-1含量增多参与了CVS的过程,与CVS的发生、发展密切相关;ND可降低SAH后CVS时血浆BNP、ET-1的水平。     

Fluoroaluminate induces rapid release of endothelin-1 in the isolated perfused arterial and venous vessels of the rat mesentery

• 1.1. Endothelin-1 (ET-1) production from endothelial cells is generally believed to be a process that happens over the course of hours.
• 2.2. When fluoroaluminate (AIF₄⁻) was infused in the isolated perfused arterial and venous vessels of the rat mesentery there was an increase in perfusion pressure on both sides.
• 3.3. Treatment of mesentery with the endothelin receptor antagonists FR 139317 (ET_A receptor selective) or PD 145065 (ET_A-ET_B receptor nonselective) caused inhibition on both the arterial and venous sides, suggesting that response is mediated predominantly by endothelin-1 through ET_A receptors.
• 4.4. Endothelial denudation attenuated changes in perfusion pressure of mesenteric circulation generated by fluoroaluminate, but not those caused by exogenously added PGF_2α.
• 5.5. Our data demonstrate that there is an immediate release of endothelin-1 following fluoroaluminate infusion which could be partially mediated by activation of phospholipase C.

     

Comparison of the effects of intra-arterial and aerosol administration of endothelin-1 (ET-1) in the guinea-pig isolated lung.

1. Intra-arterial injection of endothelin-1 (ET-1, 400 pmol; 1 microgram) in guinea-pig isolated perfused lungs, induced increases in pulmonary inflation pressure (PIP) and perfusion pressure (PPP), associated with oedema formation and thromboxane B2 (TxB2) release but not with the generation of sulphidopeptide leukotrienes or release of histamine. In contrast, aerosol administration of ET-1 (3, 6, 10 micrograms ml-1, for 2 min) evoked a dose-dependent increase in PIP, without significant changes in PPP, oedema formation or TxB2 release. 2. Addition of indomethacin (5 microM) or BW 755C (10 or 100 microM), but not nordihydroguaiaretic acid (NDGA, 50 microM) or FPL 55712 (10 microM), to the perfusion medium led to a significant inhibition of the increases in PIP and PPP, TxB2 release and oedema formation evoked by intra-arterial injection of 400 pmol ET-1. In contrast, indomethacin (5 microM), BW 755C (100 microM) or FPL 55712 (10 microM), added to the perfusion medium 10 min prior to challenge, did not affect the increase in PIP induced by a 2-min aerosol of a solution of ET-1 10 micrograms ml-1. 3. In vivo aerosol administration of indomethacin (100 mg ml-1, for 20 min) to non-anaesthetized guinea-pigs, 15 min before lung removal, did not modify the bronchopulmonary response evoked in isolated perfused lungs by an aerosol of ET-1 10 micrograms ml-1. However, under the same experimental conditions, indomethacin significantly inhibited TxB2 release evoked by aerosolized arachidonic acid (2 mg ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Calcium dependence of the contraction produced by endothelin (ET-1) in isolated guinea-pig trachea.

Endothelin (ET-1, 1 pM to 0.1 microM) produced a concentration-dependent contraction of isolated guinea-pig trachea. BAY K 8644 (1 microM) did not significantly alter the concentration-response curve for ET-1. Incubation with nicardipine (10 microM) partly inhibited responses to low concentrations (10 pM to 1 nM) of ET-1 while verapamil (10 microM) and diltiazem (10 microM) were ineffective. La3+ (10 microM) and Cd2+ (10 microM) preferentially depressed the responses evoked by high concentrations (30 nM-0.1 microM) of ET-1 without affecting the responses evoked by low concentrations of the peptide. Incubation in Ca2(+)-free (with EDTA, 1 mM) medium resulted in suppression of the responses elicited by low concentrations of ET-1 and partial inhibition of the responses elicited by high concentrations of the peptide. It is concluded that responses to ET-1 are dependent on extracellular Ca2+. The promotion of Ca2+ entry by ET-1 is not confined to a particular class of Ca2+ channel. An intracellular source of Ca2+ is also mobilized by high concentrations (greater than 10(-9) M) of ET-1.     

Hydroxylamine dilates resistance blood vessels of the perfused rat kidney and mesentery

Hydroxylamine (ED50 values, 47 +/- 8.9 nmol and 320 +/- 39 nmol) dilates resistance arterioles of the perfused noradrenaline-preconstricted rat kidney and mesentery. In this respect hydroxylamine was approximately 63x and 320x less potent than acetylcholine (ACh) and 15x and 128x less potent than nitroprusside in the two perfused organs studied. The vasodilator effect of hydroxylamine (unlike that of ACh) was unaffected by CHAPS de-endothelialization suggesting that its effect is independent of endothelium-derived relaxing factor (EDRF).     

Amino acids dilate resistance blood vessels of the perfused rat mesentery

The vasodilator effect of several L-amino acids in the perfused, noradrenaline-preconstricted rat mesentery preparation has been investigated. N-alpha-Benzoyl-L-arginine ethyl ester (BAEE) (ED50, 1.4 +/- 0.09 mumol) and L-alanine methylester (ED50, 0.9 +/- 0.007 mumol) were the most potent although L-arginine methylester, hydroxamate and hydrochloride, N-alpha-benzoyl-L-arginine methyl ester (BAME), L-methionine methylester, L-lysine hydroxamate and L-glutamic acid methylester exhibited similar potency with ED50 values in the range 2.4-3.7 mumol. L-Homoarginine chloride was inactive at doses up to 20 mumols. D-Arginine hydrochloride and D-lysine hydroxamate were inactive at doses up to 50 mumols whilst D-methionine methylester (50 mumols) produced small falls in perfusion pressure in only 3 out of 7 preparations studied. Responses to BAEE, BAME, L-arginine hydrochloride, L-alanine methylester, L-methionine methylester, L-lysine hydroxamate and acetylcholine (but not nitroprusside) were significantly inhibited by CHAPS (4.7 mg mL-1, 30 s) de-endothelialization as well as pretreatment of mesentery preparations with gossypol (3 microM). Responses to BAEE, BAME, L-arginine hydrochloride, L-alanine methylester and acetylcholine were similarly selectively reduced by NDGA (10 microM) pretreatment. We propose that these L-amino acids exhibit vasodilator activity in the perfused rat mesentery by virtue of releasing endothelium-derived nitric oxide (EDNO).     

Endothelin-1 (ET-1) and vein graft failure and the therapeutic potential of ET-1 receptor antagonists

Despite the exploration of a large number of disparate drugs in animal models and clinical trials, no pharmacological intervention, with the exception of aggressive lipid lowering therapy has reduced late vein graft failure in man. The importance of devising more effective strategies is exemplified by the enormous economic consequences of vein graft failure. Worldwide, there are currently more than 1,000,000 coronary artery bypass graft surgery (CABG) operations a year, the same number of patients undergoing infrainguinal bypass for vascular diseases of the lower limb. The pathophysiology of vein graft failure is complex, involving disparate factors that include adhesion of platelets and leukocytes, rheological forces, metalloproteinase expression, proliferation and migration of vascular smooth muscle cells, neointima formation, oxidative stress, hypoxia and neural re-organisation. Although this diverse etiology may seem to preclude any single drug type as being effective in mediating vein graft failure: one factor that is involved in every facet of vein graft pathobiology is endothelin-1 (ET-1). As such a single drug type (ET_A antagonist) may prove to be the magic bullet in this scenario. Thus, in this review, we will consider the etiology of vein graft disease in relation to ET-1 and will then present an argument (with evidence) that specific ET_A receptor antagonists constitute a potentially effective means of preventing vein graft failure.     

Effects of Goniopora toxin on guinea-pig blood vessels

Summary Effects of a marine polypeptide, Goniopora toxin (GPT) (molecular weight 12,000), were examined in isolated blood vessels of guinea pigs. GPT, ranging from 10–100 nM, augmented the contractile response to electrical transmural stimulation in the thoracic aorta, portal vein, and mesenteric and femoral arteries. The effects were abolished by tetrodotoxin and bretylium, and were markedly attenuated by phentolamine. As GPT did not affect the resting tension, spontaneous rhythmicity or noradrenaline-induced contraction, the toxin appears to act on the neural elements in the vascular wall rather than on the smooth muscle. In the portal vein preloaded with³H-noradrenaline, GPT enhanced the³H-efflux in response to electrical transmural stimulation, yet had no effect on the spontaneous efflux. The increase in stimulation-evoked³H-efflux caused by GPT was more than 15 times larger than the increase seen with cocaine or phentolamine. Tetrodotoxin completely blocked the³H-efflux induced by electrical transmural stimulation. These data suggest that GPT acts on nerve components in guinea pig blood vessels and increases the release of noradrenaline evoked by electrical stimulation of the nerve fibers. These effects are probably associated with prolongation of the action potential duration and repetitive discharges in the adrenergic nerve fibers.This work was supported in part by Grant in Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan (No. 44026), and by the Mitsubishi Foundation Research Grant for 1978     

Effect of cordiamine and corasol on the tonus of the lymphatic vessels]

The action of cordiamine and pentylene tetrazole upon the tonicity of the thoracic and jugular lymph trunks and the arterial pressure was studied in acute experiments on dogs by employing perfusion with Lock's solution under constant pressure. It is shown that pentylene tetrazole forces down, as a rule, the lymph vessels tone, while cordiamine primarily brings it up.     

后腹腔镜肾蒂淋巴管结扎术治疗乳糜尿10例

目的总结后腹腔镜肾蒂淋巴管结扎术治疗乳糜尿的经验.方法10例患者,其中男5例,女5例;年龄30～61岁;左侧4例,右侧6例;10例均行后腹腔镜肾蒂淋巴管结扎术.观察手术时间、术中出血量、术中术后并发症及手术效果.结果手术时间70～120min,平均90 min,术中平均出血约70 ml;术后当日10例乳糜尿消失,3例患者术后出现肉眼血尿,3～5 d后消失.平均住院7.6 d.随访2～20月,无乳糜尿症状复发.结论后腹腔镜肾蒂淋巴管结扎术治疗乳糜尿是一种安全、有效的方法,具有损伤小、恢复快、住院时间短、并发症少等优点,且结扎淋巴管较传统开放性手术彻底.     

后腹腔镜脂肪囊外肾蒂淋巴管结扎术治疗乳糜尿

目的 探讨后腹腔镜下脂肪囊外肾蒂淋巴管结扎术治疗乳糜尿手术方法和临床效果.方法 15例患者均行后腹腔镜脂肪囊外肾蒂淋巴管结扎术.结果 15例患者手术均成功,平均手术时间105 min,术中出血量平均70 ml.术后次日下床活动,未见明显的外科并发症.术后平均住院6.5 d,出院时尿乙醚试验全部阴性,随访3～18个月无复发.结论 该术式具有创伤更小,出血少,恢复快等优点,是目前治疗乳糜尿较理想的手术方式.     

A dual action of histamine on guinea-pig lung vessels

1. In isolated guinea-pig lungs perfused through the pulmonary artery, histamine caused a rise in perfusion pressure which was converted to a fall by a prior injection of mepyramine.

2. Evidence is provided to show that at least part of the histamine effect was due to its direct action on pulmonary vascular tissue, and was largely independent of bronchomotor tone.

3. Neither the pressor nor the depressor effects were modified by adrenoceptor blocking agents, phentolamine and propranolol, in doses which reversed or blocked the effects of noradrenaline, adrenaline or isoprenaline. The actions of histamine could therefore not be attributed to catecholamine release. The involvement of cholinergic mechanisms was also excluded since atropine failed to influence the histamine effects.

4. It is suggested that the mepyramine-sensitive pressor, and the mepyramine-resistant depressor effects of histamine, were mediated by different receptors.

5. It is proposed that a vasodilator action of histamine leading to a partial obstruction of the pulmonary airways could be part of the explanation for the relative ineffectiveness of mepyramine in blocking anaphylactic bronchoconstruction in the guinea-pig.

     

Contractile activity of three endothelins (ET-1, ET-2 and ET-3) on the human isolated bronchus.

1. The effects of three endothelins: (i) the classical or human/porcine endothelin (ET-1); (ii) [Trp6, Leu7] endothelin (ET-2) and (iii) [Thr2, Phe4, Thr5, Tyr6, Lys7, Tyr14] endothelin or rat endothelin (ET-3) were tested on the human isolated bronchus. 2. ET-1 produced a concentration-dependent contraction of the human isolated bronchus that proceeded in two different steps. The first step was observed at very low concentrations (pD2 = 11.01 +/- 0.17, n = 10) but corresponded to a low intrinsic activity (Emax = 15.6 +/- 1.8% of Emax = 26.1 +/- 2.9% of ACh 3 x 10(-3) M, n = 5, P less than 0.05), reduced by nicardipine 10(-6) M (Emax = 6.0 +/- 2.6% of ACh 3 x 10(-3) M, n = 5, P less than 0.05) and strongly inhibited in calcium-free medium. The second step of the action of ET-1 corresponded to a lesser potency (pD2 = 7.90 +/- 0.17, n = 9) but a higher intrinsic activity (Emax = 82.5 +/- 4.7% of ACh 3 x 10(-3) M). This effect was not significantly modified by nicardipine 10(-6) M or by Bay K 8644 10(-7) M. Neither of the two effects was modified by indomethacin 3 x 10(-6) M. 3. The effects of ET-2 and ET-3 were qualitatively similar to those of ET-1 but quantitatively different; for these two steps of contracting activity and for potency and efficacy the ranking was: ET-1 greater than ET-2 = ET-3.(ABSTRACT TRUNCATED AT 250 WORDS)