Nitric oxide, but not vasopressin V2 receptor-mediated vasodilation, modulates vasopressin-induced renal vasoconstriction in rats

The renal vascular response to vasopressin and its modulation were evaluated in vivo by infusing the peptide directly into the renal artery of anaesthetized rats. The intra-renal artery (i.r.a) infusion of vasopressin induced a dose-dependent decrease in renal blood flow. Vasoconstriction was obvious at a dose of 3 ng/kg per min and reached a maximum at 100 ng/kg per min. The dose required for a half-maximal response (ED50) was 24+/-4 ng/kg per min (mean+/-SEM, n=8), corresponding to an estimated concentration in renal arterial blood required for a half-maximal response (EC50) of 1.9+/-0.6 nM. Thiobutabarbitone anaesthesia markedly increased plasma vasopressin concentration. This increase was prevented partially by hypotonic hydration of the rats without any change in the renal vascular response to exogenous vasopressin. Vasopressin-induced vasoconstriction dose/response curves were similar in homozygous and heterozygous Brattleboro rats. Infusion of desmopressin (1-1000 ng/kg per min, i.r.a.), a vasopressin V2 receptor-selective agonist, failed to induce renal vasodilation or vasoconstriction. In the presence of SR 49059 (1 mg/kg i.v.), a vasopressin V1A receptor antagonist that completely abolished the vasopressin-induced renal vasoconstriction, desmopressin again failed to induce vasodilation. Inhibition of nitric oxide synthase by N(omega)-nitro-L-arginine (L-NNA, 100 microg/kg for 10 min and 7.5 microg/kg per min, i.r.a.) enhanced vasopressin-induced renal vasoconstriction (EC50 0.6+/-0.1 nM, P<0.05). In contrast, cyclooxygenase blockade by indomethacin (5 mg/kg, i.v.) neither modified the vasopressin-induced decrease in renal blood flow nor altered the potentiation of vasoconstriction by L-NNA. These results show that the constrictor response of the rat renal vascular bed in vivo is observed only with high local concentrations of vasopressin. This hyporeactivity in vivo was not explained by an anaesthesia-elicited increase in endogenous vasopressin, nor by a modulatory effect linked to V2 receptor activation or prostanoid release. In contrast, NO release contributed to the attenuation of vasopressin-induced renal vasoconstriction.     

Aqueous extract of Annona squamosa (L.) ameliorates renal failure induced by 5/6 nephrectomy in rat

Objective:

To assess the renoprotective activity of the water extract of Annona squamosa in 5/6 nephrectomized animals.

Materials and Methods:

For evaluating the renoprotective effects of Annona squamosa, 5/6 nephrectomized rats were used as a model for renal failure. The effects of hot-water extract of leaves of Annona squamosa L. (A. squamosa) at a dose 300 mg/kg bw on biochemical and urinary parameters like plasma urea, plasma creatinine, and urine creatinine were analyzed. For elucidating its effect on oxidative stress, renal superoxide dismutase (SOD) levels were measured.

Results:

Nephrectomized rats (5/6) showed a significant rise in plasma urea and creatinine levels with a stable fall in urine creatinine. Treatment with A. squamosa extract (300 mg/kg bw) lead to a significant fall in the plasma urea and creatinine values with partial restoration to normal values along with a significant rise in the activity of SOD.

Conclusion:

Thus, therapeutic strategies against oxidative stress could be effective in renal diseases. This study provides an indication to investigate further the efficacy of A. squamosa as a novel agent for alleviating renal failure.KEY WORDS: Annona squamosa, anti-oxidant, renal failure     

替米沙坦对5/6肾切除肾衰竭大鼠的肾脏保护作用及其机制研究

目的 探讨血管紧张素AT1受体拮抗剂替米沙坦对5/6肾切除肾衰大鼠的肾脏保护作用及可能作用机制.方法 选用180 ～ 200 g雄性SD大鼠30只建立5/6肾切除肾衰模型,分为假手术组、模型组和替米沙坦组,各10只.第12周时采用断头法处死大鼠,并检测各组大鼠血清尿素氮、肌酐及24h尿蛋白水平;取残余肾组织行病理检查,判断肾小球硬化、肾小管间质损伤程度;利用反转录聚合酶链反应( RT-PCR)和Western Blot检测过氧化物酶增殖体活化受体γ(PPARγ)和神经型一氧化氮合酶(nNOS)蛋白和mRNA的表达水平.结果 3组肌酐、血清尿素氮及24 h尿蛋白情况:假手术组:(35±4)μmol/L,(6.6±1.0) mmol/L,(30 ±4) mg/d;模型组:(91±10) μmol/L,(23.0±3.4)mmol/L,(96±21) mg/d;替米沙坦组(62±10) μmol/L,( 15.3 - 1.3) mmol/L,(45±17) mg/d;与假手术组相比,模型组和替米沙坦组大鼠上述指标均明显升高(P＜0.01);但与模型组相比,替米沙坦组各指标则明显降低(P＜0.05).病理学检查示模型组大鼠肾组织有明显的肾小球硬化及肾小管间质损伤,肾小球硬化指数及肾小管间质损伤指数均较假手术组明显增高(P＜0.01);而替米沙坦组上述指标则较模型组明显降低(P＜0.05).Western Blot和RT-PCR显示模型组PPARγ、nNOS蛋白和mRNA的表达较假手术组明显下降(P＜0.05),而替米沙坦组PPARγ和nNOS的表达则较模型组明显升高(P＜0.05).结论 大鼠5/6肾切除后,给予替米沙坦可以明显减轻肾小球硬化和肾间质纤维化的程度,其作用机制可能与其上调PPARγ和nNOS基因的表达有关,且二者有明显的相关性.     

Potent V2/V1a vasopressin antagonists with C-terminal ethylenediamine-linked retro-amino acids.

We report the solid-phase synthesis and antagonistic potencies of 25 analogues (1-25) of [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-O-ethyl-D-tyrosine,4-valine]arginine-vasopressin (d(CH2)5D-Tyr(Et)2-VAVP) (A) and of the related Ile4 (D) and [D-Phe2,Ile4] (E) analogues, potent antagonists of the antidiuretic (V2-receptor) and of the vasopressor (V1a-receptor) responses to arginine-vasopressin (AVP). Six of these peptides (1, 13, 17, 19, 21, and 23) have the Pro-Arg-Gly-NH2 tripeptide side chain fully or partially replaced or extended by ethylenediamine (Eda). The remaining 19 peptides have L- or D-amino acids retrolinked to these six C-terminal Eda peptides. Peptides 1, 13, 17, and 19 all have the ring structure of (A). Their side-chain structures are as follows: 1, Eda; 13, Pro-Eda; 17, Pro-Arg-Eda; 19, Arg-Gly-Eda. Peptide 21 is the Pro-Arg-Eda analogue of D; peptide 23 is the Pro-Arg-Gly-Eda analogue of E. Peptide 2 is the retro-Arg analogue of 1. Its side-chain structure is Eda<--Arg. Peptides 3-6 are analogues of 2 which have the D-Tyr-(Et)2 residue replaced by L-Tyr(Et)2 (3), D-Phe2 (4), D-Ile2 (5), or D-Leu2 (6), respectively. Peptides 7-12 are analogues of 2 which have the C-terminal retro-Arg replaced in retrofashion by D-Arg (7), Gly (8), Orn (9), D-Orn (10), D-Lys (11), or Arg-Arg (12). Peptides 14-16 have D-Orn (14), D-Lys (15), and D-Arg (16) retrosubstituted to peptide 13. Peptides 18, 20, and 22 are the retro-Arg-substituted analogues of 17, 19, and 21, respectively. Peptides 24 and 25 have Val and D-Val in retrolinkage with 23, respectively. All 25 peptides were examined for agonistic and antagonistic potencies in AVP V2/V1a assays. With the exception of peptides 5 and 6, all exhibit potent anti-V1a antagonism, with anti-V1a pA2 values in the range 7.64-8.33.(ABSTRACT TRUNCATED AT 400 WORDS)     

L-精氨酸致大鼠残余肾代偿性增生与NO无关

目的　探讨L 精氨酸 (L arg)对肾大部切除大鼠 (SNx)残余肾代偿性增生的影响及其与一氧化氮 (NO)的关系。方法　采用 5 /6SNx为实验模型 ,实验组于手术后分别给予 1%L arg或NO供体Molsidomine(MSD)。实验分假手术 (Sham)、SNx、SNx L arg、SNx MSD 4组 ,观察指标为体重、残余肾重、肾重 /体重比 (KW/BW)、尿蛋白定量、血压、肌酐清除率 (Ccr)、残余肾代偿性增生比率 (CRG)、残余肾蛋白质、DNA含量、小管间质细胞增殖细胞核抗原 (PCNA)免疫组化表达、尿NO代谢产物NO-2 排泄量等。结果　L arg组大鼠尿残余肾代偿性增生指标 (KW、KW/BW、CRG、蛋白质、DNA及PCNA等 )较其对照组明显增加 (P分别小于 0 0 5 ,0 0 1) ,MSD组上述指标与SNx组相比无显著统计学差异 (P >0 0 5 )。L arg及MSD组NO-2 排泄量均较SNx组显著增加。结论　L arg可刺激大鼠残余肾代偿性增生 ,这种作用可能与NO无关     

N alpha-acetyl-[Arg8]vasopressin antagonizes the behavioral effect of [Cyt6]vasopressin-(5-9), but not of vasopressin

It has been found recently that N alpha-acetyl-[Arg8]vasopressin (Ac-VP) is present in the brain of rats. The physiological significance of this peptide is as yet unknown. Therefore, the central nervous system effects of this peptide were investigated, namely, its effects on passive avoidance behavior, exploratory behavior and body temperature. The interaction of Ac-VP with the central nervous system effects of vasopressin (VP) was also studied. Ac-VP had a slight agonistic effect on passive avoidance behavior, i.e. it facilitated passive avoidance behavior at a dose 100 times higher than that of VP. Relatively low doses (3-10 ng) of Ac-VP attenuated passive avoidance behavior, which suggests that Ac-VP interfered with an endogenous compound involved in the control of passive avoidance responding. Ac-VP was also able, albeit in higher doses (30 ng), to competitively antagonize the effect of [Cyt6]VP-(5-9), a highly potent, putative endogenous metabolite of vasopressin in the rat brain. This antagonism could be due to an interaction of Ac-VP with sites other than the V1 vasopressin receptor. Ac-VP had no significant influence on other central nervous system effects of the hormonally active nonapeptide VP, such as exploratory behavior and body temperature. These effects were readily antagonized by the V1 vasopressin receptor antagonist d(CH2)5Tyr(Me)VP. Ac-VP may be competitive antagonist of behaviorally active vasopressin metabolite(s) in the brain.     

Two highly effective V1/V2 antagonists of vasopressin containing novel thioacids at position 1.

In an attempt to develop more effective and selective V1/V2 antagonists of arginine vasopressin (AVP), two analogues have been designed and synthesized. In position 1 they contain thioacids that include a heteroatom in the cyclohexane ring. The 4-thio-4-tetrahydrothiopyraneacetic acid modification of position 1 used in one of them had advantages over the 1-mercaptocyclohexaneacetic acid substituted compound used as reference. The new compound was weaker at lower doses, but elicited a greater response at higher doses, whereas the reference compound reached its plateau earlier. Although the 4-thio-4-tetrahydropyraneacetic acid substitution used in the second compound resulted in a less potent analogue on a weight basis, this substitution also confers enhanced overall efficacy in terms of magnitude of effect.     

Effects of YM218, a nonpeptide vasopressin V1A receptor-selective antagonist, on human vasopressin and oxytocin receptors.

The binding and signal transduction characteristics of YM218 ((Z)-4'-{4,4-difluoro-5-[2-oxo-2-(4-piperidinopiperidino)ethylidene]-2,3,4,5-tetrahydro-1H-1-benzoazepine-1-carbonyl}-2-methyl-3-furanilide hemifumarate), a newly synthesized, potent arginine vasopressin (AVP) V(1A) receptor-selective antagonist, were examined using cloned human AVP receptors (V(1A), V(1B) and V(2)) stably expressed in Chinese hamster ovary (CHO) cells and human uterine smooth muscle cells (USMCs) expressing oxytocin receptors. YM218 potently inhibited specific binding of [(3)H] AVP to V(1A) receptors, exhibiting a K(i) value of 0.30 nM. In contrast, YM218 exhibited much lower affinity for V(1B), V(2) and oxytocin receptors, exhibiting K(i) values of 25,500 nM, 381 nM and 71.0 nM, respectively. In CHO cells expressing V(1A) receptors, YM218 potently inhibited the AVP-induced increase in intracellular Ca(2+) concentration ([Ca(2+)](i)), exhibiting an IC(50) value of 0.25 nM. However, in human USMCs expressing oxytocin receptors, YM218 exhibited a much lower potency in inhibiting the oxytocin-induced [Ca(2+)](i) increase, showing an IC(50) value of 607 nM, and had no effect on the AVP-induced [Ca(2+)](i) increase in CHO cells expressing V(1B) receptors. Furthermore, in CHO cells expressing V(2) receptors, YM218 did not potently inhibit the production of cAMP stimulated by AVP, showing an IC(50) value of 62.2 nM. In all assays used, YM218 did not exhibit any agonistic activity. These results demonstrate that YM218 is a potent, nonpeptide human V(1A) receptor-selective antagonist, and that YM218 will be a valuable new tool to gain further insight into the physiologic and pharmacologic actions of AVP.     

Modulation of the 5-HT1C receptor-mediated behavior by 5-HT2, but not 5-HT1A, receptor activation.

The effects of 5-HT1A-receptor agonists 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) and gepirone, a 5-HT1A/5-HT2-receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and a 5-HT2-receptor agonist (+-)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ((+/)DOI) on the 5-HT1C-receptor-mediated exploratory hypoactivity in rats, induced by m-trifluoromethylphenylpiperazine (TFMPP) or m-chlorophenylpiperazine (m-CPP), were studied in the open field test. (+/-)DOI attenuated the effects of TFMPP and abolished those of m-CPP (not dose-dependently). 5-MeODMT showed a weak antagonistic action only at one, intermediate dose. The effects of TFMPP or m-CPP were not changed by 8-OH-DPAT or gepirone. At the same time, 8-OH-DPAT, gepirone, 5-MeODMT and (+/-)DOI themselves practically did not change the exploratory activity of rats. The obtained results permit an assumption that a functional interaction exists between 5-HT1C- and 5-HT2-receptors, but not between 5-HT1C- and 5-HT1A-ones.     

Cyclooxygenase 1 and/or 2 blockade ameliorates the renal tissue damage triggered by ischemia and reperfusion injury

Ischemia-reperfusion injury (IRI) is a common event in organ transplantation, being implicated as a potential contributor for the development of chronic allograft nephropathy. There are new evidences showing a tissue inflammatory response following renal IRI. Cyclooxygenases (COX) 1 and 2 can be detected in tissue submitted to IRI and may have impact on organ function outcome. We evaluated the role of COX inhibition on the renal tissue damage that follows IRI. Mice were submitted to 45 min of renal pedicle ligature and allowed to reperfuse for 24, 48, 72 and 120 h. Blood and kidney samples were collected at reperfusion times. mRNA was extracted from the kidney samples to amplify COX-1, COX-2 and beta-actin genes. Animals were pretreated with indomethacin or rofecoxib before the surgery. Indomethacin treatment induced a better renal function (serum urea) when compared to control animals at 24, 48 and 72 h (219+/-54.5 vs. 338+/-51 mg/dl; 106+/-51 vs. 326+/-86 mg/dl; 94+/-14 vs. 138+/-38 mg/dl, respectively). Surprisingly, rofecoxib use was associated with even better renal improvement following IR. Animals treated with the later drug showed lower urea values at 24 h post reperfusion compared to indomethacin-treated animals (128+/-33 vs. 219+/-54.5 mg/dl, P<0.05). Blockade of COX-1 and -2 resulted in a decrease of tubular necrosis. mRNA COX-2 was up-regulated post IRI and considerable inhibited after indomethacin or rofecoxib treatment. Our data show COX-1/-2 participates in the inflammatory tissue response to IR injury and its inhibition is associated with an improvement in renal function.     

tPA, but not uPA, significantly affects antithrombotic therapy by a glycoprotein IIb/IIIa antagonist, but not by a factor Xa inhibitor

To define the interaction of fibrinolytic components with platelets or coagulation factors on thrombus formation, we investigated mouse deficient in tissue plasminogen activator (tPA -/-) or urokinase plasminogen activator (uPA -/-) and in their wild-type control (tPA +/+, uPA +/+). A thrombus was induced in the murine carotid artery using photochemical reaction. Blood flow was monitored and the time needed before the vessel became completely obstructed was within 12 min in all types of mice. When DX-9065a, a selective factor Xa inhibitor, or GR144053, a platelet glycoprotein (GP) complex IIb/IIIa antagonist was applied, the time required to occlusion was prolonged in a dose-dependent manner in all types of mice. When a factor Xa inhibitor was injected in tPA -/- mice, the estimated ED50 was not changed. However, when GR144053 was injected in tPA -/- mice, the most significant changes were observed: the estimated ED51 was 19.6 times higher than the one in tPA +/+ mice. Platelet aggregation, hemostasis tests, and bleeding times were not significantly different among the different types of mice. In conclusion, the antithrombotic effect of platelet inhibition by a GPIIb/IIIa antagonist, is severely affected by the absence or presence of tPA production. On the contrary, the inhibition of factor Xa shows a stable antithrombotic effect with or without tPA. Thus the lack of tPA, but not of uPA, significantly affects antithrombotic efficacy.     

Cardiovascular and renal effects of conivaptan hydrochloride (YM087), a vasopressin V1A and V2 receptor antagonist, in dogs with pacing-induced congestive heart failure.

The systemic hemodynamic and renal responses to conivaptan hydrochloride (YM087; 4'-(2-methyl-1,4,5,6-tetrahydroimidazo[4,5-d][1]benzoazepine -6-carbonyl)-2-phenylbenzanilide monohydrochloride), a vasopressin V1A and V2 receptor antagonist, were determined in pentobarbital-anesthetized dogs after 2 to 3 weeks of rapid right ventricular pacing. Congestive heart failure, characterized by decreases in first derivative of left ventricular pressure (left ventricular d P/dt(max)) and cardiac output, and increases in left ventricular end-diastolic pressure and total peripheral vascular resistance, was induced by chronic rapid right ventricular pacing at 260-280 beats/min. Intravenous administration of conivaptan (0.1 mg/kg) significantly increased left ventricular dP/dt(max) and cardiac output and significantly decreased left ventricular end-diastolic pressure and total peripheral vascular resistance. Conivaptan also increased urine flow and reduced urine osmolality by markedly increasing free water clearance. These results indicate that conivaptan produced hemodynamic improvement and marked aquaresis in dogs with congestive heart failure. Therefore, conivaptan may find clinical use in treating patients with congestive heart failure.     

P2-, but not P1-purinoceptors mediate formation of 1, 4, 5-inositol trisphosphate and its metabolites via a pertussis toxin-insensitive pathway in the rat renal cortex.

1. The adenosine receptor (P1-purinoceptor) agonists N6-cyclopentyladenosine and N-5'-ethyl-carboxamidoadenosine at concentrations up to 10 mumols 1(-1) affected neither basal, nor noradrenaline- and angiotensin II-stimulated formation of inositol-1-phosphate, inositol-1,4-bisphosphate, and inositol-1,4,5-trisphosphate in slices of rat renal cortex. 2. In contrast, adenine nucleotides (P2-purinoceptor agonists) markedly stimulated inositol phosphate formation. The observed rank order of potency adenosine-5'-O-(2-thiodiphosphate) (EC50 39 mumols 1(-1] greater than adenosine-5'-O-(3-thiotriphosphate) (587) greater than or equal to 5'-adenylylimidodiphosphate (App(NH)p, 899) greater than adenylyl-(beta, gamma-methylene)-diphosphate (4,181) was consistent with the interaction of the compounds with the P2Y-subtype of P2-purinoceptors. AMP and the ADP analogue (alpha, beta-methylene)-adenosine-5'-diphosphate were ineffective. ATP and ADP (less than or equal to 10 mmol 1(-1] did not produce a consistent increase, owing to their hydrolytic degradation in the incubation medium. 3. Whereas the inositol phosphate response to App(NH)p was linear only up to 5 min incubation, the time-dependent stimulation of noradrenaline declined at a slower rate. Following pre-exposure of the renal cortical slices to App(NH)p, renewed addition of App(NH)p caused no further enhancement in the accumulation of inositol phosphates, whilst noradrenaline was still capable of eliciting a response. This suggests that the apparent loss of responsiveness to App(NH)p is not due to substrate depletion or enzymatic inactivation, but most likely attributable to homologous desensitization of the purinoceptor.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetic and pharmacodynamic effects of YM087, a combined V1/V2 vasopressin receptor antagonist in normal subjects

Objective: The pharmacokinetic and pharmacodynamic properties of YM087, (4′-[(2-methyl-1,4,5,6-tetrahydroimidazo[4,5-d][1]benzazepin-6-yl)-carbonyl]-2-phenylbenzanilide monohydrochloride), a new orally active, dual V₁/V₂ receptor antagonist were characterised in healthy normotensive subjects. Methods: Six subjects were randomly allocated to receive, at 1-week intervals, a single oral dose of 60 mg YM087 and a single i.v. dose of 50 mg YM087 in an open-label, crossover study. Results: YM087 had an oral bioavailability of 44% and a short half-life. Upon oral and i.v. administration of YM087, a significant sevenfold increase in urine flow rate and a fall in urinary osmolality (from 600 mosmol/l to less than 100-mosmol/l) were observed with a peak effect 2 h after drug intake suggesting effective vasopressin V₂ receptor blockade. Simultaneously, significant increases in plasma osmolality (from 283 ± 1.3 mosmol/l to 288 ± 1.0 mosmol/l after i.v. and from 283 ± 2.1 mosmol/l to 289 ± 1.7-mosmol/l after oral administration) and vasopressin levels (from 1.5 ± 0.3 pg/ml to 3.7 ± 0.6 pg/ml after i.v. and from 0.9 ± 0.1 pg/ml to 3.9 ± 0.7 pg/ml after oral administration) were found. When administered i.v., YM087 inhibited the vasopressin-induced skin vasoconstriction, suggesting a blockade of V₁ receptors. However, the YM087-induced antagonism of V₁ receptors was less pronounced than V₂ receptor blockade. Conclusion: These data show that YM087 is an effective dual V₁/V₂ receptor antagonist in man. Received: 17 February 1999 / Accepted in revised form: 18 August 1999     

缬沙坦及苯那普利对5/6肾切除大鼠肾小球硬化的影响

目的 :观察并比较缬沙坦及苯那普利对 5 6肾切除大鼠肾小球硬化的改善作用 ,探讨其作用机制。方法 :选用SD雄性大鼠 30只 ,通过 5 6肾切除法制造慢性肾功能衰竭模型 ,术后 2周随机分为模型组、缬沙坦组及苯那普利组 ,并设假手术组作为对照。术后第 6周末各组大鼠进行体重、血压、血清肌酐 (Scr)及尿素氮 (BUN)的测定 ,处死大鼠 ,取出肾组织进行病理组织形态学观察 ,并采用免疫组织化学方法检测肾组织转化生长因子 β1(TGF β1)、IV型胶原、纤维连接蛋白 (FN)表达。结果 :同模型组相比 ,两治疗组收缩压下降 (P均 <0 .0 1) ,肾功能改善 ;肾小球系膜增殖程度、肾小球硬化指数 (GSI)降低 (P均 <0 .0 1) ;免疫组化染色显示 ,两治疗组肾小球转化生长因子 β1(TGF β1)、纤维连接蛋白 (FN)及IV型胶原表达均较模型组下降 (P均 <0 .0 1)。结论 :缬沙坦及苯那普利对慢性肾功能衰竭大鼠具有同等的肾脏保护作用 ;改善肾小球硬化是通过减少肾小球TGF β1表达 ,从而减少FN及IV型胶原生成来实现的。     

Glucocorticoids and IL-10, but not 6-MP, 5-ASA or sulfasalazine block endothelial expression of MAdCAM-1: implications for inflammatory bowel disease therapy

BACKGROUND: Enhanced MAdCAM-1 (mucosal addressin cell adhesion molecule-1) expression is associated with the aetiology of inflammatory bowel disease, but little is known about MAdCAM-1: regulation, or how inflammatory bowel disease therapies modulate MAdCAM-1. AIM: To examine how agents currently used to treat inflammatory bowel disease affect MAdCAM-1: induced by tnf-alpha in an in vitro model of inflammatory bowel disease. METHODS: Endothelial monolayers were pretreated with dexamethasone (DEX): 5-aminosalicylic acid (5-ASA), 6-mercaptopurine (6-MP), sulfasalazine or interleukin-10: (IL-10: prior to TNF-alpha (20 ng/mL), and MAdCAM-1: measured by Western blotting, RT-PCR, EMSA and lymphocyte adhesion assays. RESULTS: MAdCAM-1: was induced dose- and time-dependently by TNF-alpha on endothelial cells. Either dexamethasone or IL-10: reduced TNF-alpha-induced MAdCAM-1: protein, mRNA and lymphocyte adhesion. However, neither 5-ASA, sulfasalazine nor 6-MP blocked MAdCAM-1 induction. CONCLUSIONS: Our data indicate that dexamethasone or IL-10 can exert therapeutic activity in inflammatory bowel disease through MAdCAM-1 inhibition. 5-ASA, sulfasalazine and 6-MP, while beneficial in inflammatory bowel disease, do not directly control MAdCAM-1, and are beneficial through inhibition of other inflammatory processes.     

Pharmacology of conivaptan hydrochloride (YM087), a novel vasopressin V1A/V2 receptor antagonist

Pharmacology of conivaptan hydrochloride (YM087) was investigated in in vitro and in vivo studies. In radioligand binding study, YM087 showed high affinity for both V1A and V2 receptors in animal and human species. Affinity of YM087 for V1A and V2 receptors was comparable to that of vasopressin (AVP). In functional antagonistic activity study, YM087 concentration-dependently inhibited AVP-induced intracellular Ca2+ elevation via human V1A receptors and AVP-stimulated cAMP accumulation via human V2 receptors. Intravenous administration of YM087 dose-dependently inhibited AVP-induced pressor responses and produced a dose-dependent aquaresis in rats and dogs. Oral administration of YM087 showed a potent and long-lasting antagonistic activity on V1A and V2 receptors. YM087 was effective in dogs with heart failure and in heart failure rats with hyponatremia and edema. These results reveal that YM087 is the first orally active V1A/V2 receptor antagonist and suggest that YM087 may be useful in the treatment of congestive heart failure and hyponatremia.     

Cimetidine, but not oxmetidine, penetrates into the cerebrospinal fluid after a single intravenous dose.

1 Thirty-six patients with various neurological diseases or symptoms received single intravenous doses of either cimetidine 400 mg (n = 19) or oxmetidine 200 mg (n = 17), 15 or 60 min before a diagnostic lumbar puncture. 2 In the 15 min CSF samples concentrations of cimetidine were detectable but not measurable in 5 and non-detectable in 3 patients. 3 In the 60 min CSF samples the concentrations of cimetidine were detectable in all 11 patients and were measurable in 8 of these patients with a mean +/- s.e. mean of 0.12 +/- 0.01 microgram/ml. These CSF concentrations were correlated to simultaneously measured plasma concentrations (P less than 0.01). The mean ratio CSF/plasma concentration was 0.03. 4 No detectable concentrations of oxmetidine were found either in the 15 min (n = 9) or in the 60 min (n = 8) liquor samples. 5 Cimetidine penetrates the blood-drain barrier slowly and not freely after a single dose. Our data suggest that the new histamine H2-receptor antagonist oxmetidine does not cross this barrier.