β-受体阻断剂对异丙肾上腺素提高心肌耗氧量作用的影响

The blockade effect of β-receptor blockers bupranolol and ACC9089 on the increase of heart muscle oxygen consumption by isoprenaline was studied according to Castellucci's method with Warburg's apparatus on thin slices of swine heart muscle instead of the rabbit heart muscle. The results showed that Bupranolol was about 2.5 times more stronger than practolol and about 2 times more stronger than ACC-9089 to block the increase of effects of isoprenaline for swine heart muscle oxygen consumptions on equal molar concentration levels. The results showed also that only the secondary higher concentration of 4 different concentrations of ACC-9089 could block the β-receptor to decrease the heart muscle oxygen consumption in comparison with the control. It was suggested that the highest molar cone. (1.72×10^-3M) of ACC-9089 would probably show an intrinsic sympathomimetic effect which could overlay its blockade effect to β-receptors. That the β-receptor blockers would act as the competitions with isoprenaline to the β-receptors according to their similarity of the side chain chemical structures has been discussed.     

Histaprodifen, methylhistaprodifen, and dimethylhistaprodifen are potent H1-receptor agonists in the pithed and in the anaesthetized rat

Selective H₂- and H₃-receptor agonists, exhibiting an at least tenfold higher potency than histamine itself at the respective receptors, have been known for several years. Selective H₁-receptor agonists with a potency exceeding that of histamine have become available only recently; the most potent are methylhistaprodifen and dimethylhistaprodifen [N ^α-methyl- and N ^α,N ^α-dimethyl-2-(3,3-diphenylpropyl)histamine, respectively] with 3.4- and 2.4-fold higher potencies than histamine in vitro (in the guinea-pig ileum). The aim of the present study was to examine whether these compounds and the parent compound histaprodifen are potent H₁-receptor agonists in the pithed and in the anaesthetized rat. In pithed, vagotomized rats diastolic blood pressure was decreased by 2-(2-thiazolyl)ethanamine i.v. (which was used as a reference H₁-receptor agonist) and by histaprodifen, methylhistaprodifen, and dimethylhistaprodifen; the maximum decrease was about 45 mmHg for each compound, and the potencies, expressed as pED₅₀, the negative logarithm of the dose (in mole per kilogram body weight) eliciting a half-maximal response, were 7.23, 7.55, 8.43 and 8.12, respectively. The dose/response curves of the four compounds were shifted to the right to about the same extent by the H₁-receptor antagonist dimetindene (1 μmol/kg i.v.). The vasodepressor response was not affected by combined i.v. administration of the H₂- and H₃-receptor antagonists ranitidine and thioperamide, by combined i.v. administration of the α₁- and α₂-adrenoceptor antagonists prazosin and rauwolscine, and by the β-adrenoceptor antagonist propranolol i.v. but was attenuated by the inhibitor of NO synthase, N ^ω-nitro-l-arginine methyl ester i.v. In anaesthetized rats 2-(2-thiazolyl)ethanamine, histaprodifen, methylhistaprodifen and dimethylhistaprodifen i.v. also decreased diastolic blood pressure in a manner sensitive to dimetindene i.v. Our data show that histaprodifen and, in particular, methyl- and dimethylhistaprodifen are highly potent H₁-receptor agonists in vivo. Received: 3 September 1998 / Accepted: 23 October 1998     

Ontogeny of adenosine receptors in the longitudinal muscle and muscularis mucosae of the rat distal colon

The development of adenosine A₁ and A_2B receptors on the longitudinal muscle and muscularis mucosae of the neonatal rat distal colon has been investigated using homogenate binding, quantitative autoradiography and functional studies. In homogenate binding studies 1,3-[³H]-dipropyl-8-cyclopentylxanthine ([³H]DPCPX) bound with high affinity to A₁ receptors in the muscularis mucosae and intact colon from rats aged 10, 15, 20, 25 and 30 days. The affinity of [³H]DPCPX was similar to that in the adult at all ages, but the density of binding sites was higher in the neonatal tissues. Quantitative autoradiography showed a higher density of [³H]DPCPX binding sites in the longitudinal muscle than in the muscularis mucosae at all ages studied (day 10 to adult), and this binding was concentration-dependently displaced by N ⁶-cyclopentyladenosine (CPA). In functional studies the longitudinal muscle relaxed in response to 5’-N-ethylcarboxamidoadenosine (NECA) and CPA at all ages studied (15–30 days), NECA being more potent than CPA. The potency of NECA remained constant and it was antagonised by 1 μM DPCPX at all ages with pA ₂-values consistent with activation of A₂ receptors. The inactivity of 2-[p-(carboxyethyl)-phenylethylamino]-5’-N-ethylcarbox-amidoadenosine (CGS 21680) indicated that the A₂ receptors were of the A_2B subtype. The muscularis mucosae contracted in response to CPA at all ages studied (day 15 to adult) and the antagonism by DPCPX (10 nM) were consistent with activation of A₁ receptors. In conclusion, binding, autoradiographic and functional studies identified A₁ receptors on the rat colon muscularis mucosae at all ages studied. However, while binding and autoradiographic localisation showed the presence of A₁ receptors in the longitudinal muscle at all ages studied, functional data only revealed the presence of A_2B receptors. Received: 3 July 1998 / Accepted: 25 November 1998     

一叶萩碱对5种神经递质受体和蛙脊髓膜电位的影响

Using radioligand binding assay method, securinine was shown to be specifically bound to GABA receptors of rat brain with IC₅₀ of 10^(-4)～10^-5mol/L. However, securinine did not exhibit affinity for a₁-, a₂- adrenoceptors and M-cholinergic receptors of rat brain and the β-adrenoceptors of duck erythrocyte membrane. In isolated and perfused bullfrog spinal cord experiment, the depolarization induced by GABA was slightly depressed by securinine (1 mmol/L), but no antagonistic effect on glycine or taurine evoked depolarization was observed with securinine. These results indicate that securinine is a weak GABA antagonist.     

P2-Receptor-mediated inhibition of noradrenaline release in the rat hippocampus

Experiments on hippocampal slices were carried out in order to find out whether the release of noradrenaline in the hippocampus can be modulated through P2-receptors. The slices were preincubated with [³H]-nor-adrenaline, superfused with medium containing desipramine (1 μM), and stimulated electrically, in most experiments by 4 pulses/100 Hz. The adenosine A₁-receptor agonist N⁶-cyclopentyl-adenosine (CPA) and the nucleotides ATP, adenosine-5’-O-(3-thiotriphosphate) (ATPγS) and adenosine-5’-O-(2-thiodiphosphate) (ADPβS) decreased the evoked overflow of tritium by up to 55 %. The adenosine A_2a-agonist 2-p-(2-carboxyethyl)-phenethylamino-5’-N-ethylcarboxamido-adenosine (CGS 21680; 0.003-0.3 μM) caused no change. The concentration-response curve of CPA was shifted to the right by the A₁-antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 3 nM) but not by the P2-receptor antagonists cibacron blue 3GA (30 μM) and reactive blue 2 (30 μM); the apparent pK_B value of DPCPX against CPA was 9.0. In contrast, the concentration-response curve of ATP was shifted to the right by DPCPX (3 nM), apparent pK_B 8.7, as well as by ciba-cron blue 3GA (30 μM), apparent pK_B 5.2, and reactive blue 2 (30 μM), apparent pK_B 5.6; the antagonist effects of DPCPX and cibacron blue 3GA were additive in a manner compatible with the blockade of two separate receptors for ATP. The same pattern was obtained with ATPγS: its concentration-response curve was shifted to the right by DPCPX as well as by cibacron blue 3GA and reactive blue 2. Suramin (300 μM) antagonized neither the effect of ATP nor that of ATPγS. The 5’-nucleotidase inhibitor α,β-methylene-ADP (100 μM) did not change the effect of ATP. Only cibacron blue 3GA (30 μM) but not reactive blue 2 (30 μM), given alone, consistently caused a small increase of the evoked overflow of tritium. Hippocampal slices degraded exogenous ATP, and this degradation was reduced by cibacron blue 3GA (30 μM), reactive blue 2 (30 μM) and suramin (300 μM). The results indicate that the noradrenergic terminal axons of the rat hippocampus possess P2-receptors in addition to the known A₁-adenosine receptors. The presynaptic P2-receptors mediate an inhibition of noradrenaline release, are activated by nucleotides but not nucleosides, and are blocked by cibacron blue 3GA and reactive blue 2. ATP and ATPγS act at both the A₁- and the P2-receptors. An autoreceptor function of cerebral presynaptic P2-receptors remains doubtful. Received: 20 November 1996 / Accepted: 10 February 1997     

Interaction of the diuretics torasemide and U-37883A with the KATP channel in rat isolated aorta

In this study we have investigated the interaction of the loop diuretics torasemide and furosemide and of the eukalemic diuretic U-37883A (4-morpholinocarboximidine-N–1-adamantyl-N’-cyclohexylhydrochloride) with the ATP-sensitive K⁺ channel (K_ATP channel) in rat aortic rings. Torasemide contains a sulphonylurea group which might enable the compound to interfere with K_ATP channels; this group is lacking in furosemide. U-37883A blocks several types of K_ATP channels. The interaction with the vascular K_ATP channel was probed in binding studies, ⁸⁶Rb⁺ efflux experiments and vasorelaxation assays. Torasemide inhibited the binding of the K_ATP channel inhibitor [³H]glibenclamide and of the opener [³H]P1075 with IC₅₀ values of 19 and 45 μM, respectively; furosemide and U-37883A were inactive or interfered with binding in a nonspecific way. In ⁸⁶Rb⁺ efflux experiments, the loop diuretics, at μM concentrations, inhibited basal tracer efflux to 50% whereas U-37883A had no effect. P1075-stimulated ⁸⁶Rb⁺ efflux, a qualitative measure of K_ATP channel opening, was inhibited by U-37883A and torasemide with IC₅₀ values of 0.06 and 130 μM, respectively; furosemide induced only a small (23%) inhibition. In experiments measuring isometric force, torasemide and furosemide partially relaxed endothelium-denuded aortic rings precontracted with noradrenaline or KCl with EC₅₀ values between 6 and 10 μM. The vasorelaxant effect of P1075 was inhibited in a noncompetitive manner by torasemide (300 μM) but unaffected by furosemide. U-37883A increased noradrenaline-induced force and inhibited the vasorelaxant effect of P1075 in an apparently competitive manner with an inhibition constant of 0.4 μM. The data show that torasemide interferes specifically with the binding of the K_ATP channel modulators [³H]glibenclamide and [³H]P1075 and with the K_ATP channel opening and vasorelaxant effects of P1075 whereas furosemide is inactive. This suggests that the interaction of torasemide with the vascular K_ATP channel is due to the sulphonylurea group present in torasemide. U-37883A, which does not inhibit P1075 binding, is one of the most potent blockers of P1075-induced ⁸⁶Rb⁺ efflux yet described but is relatively weak as an inhibitor of P1075-mediated vasorelaxation. The opposite vascular actions of torasemide and U-37883A are expected to contribute to the renal effects of these drugs. Received: 28 January 1998 / Accepted: 20 April 1998     

血吸虫病化学治疗的研究——ⅩⅩⅩⅣ.α-氯-β-(5-硝基-2-呋喃)丙烯酰胺类及其乙烯噁二唑类衍生物的合成

Synthesis of 35 new compounds of α-chloro-β-(5-nitro-2-furyl) acrylamides and 5-[α-chloro-β-(5-nitro-2-furyl ) vinyl]-oxadiazoles by known methods are reported. In preliminary test in mice 10 compounds were found to possess pronounced activity against Schistosomiasis japonica. Among these Ⅰ₁₂, Ⅰ₁₃, Ⅰ₁₄, Ⅰ₂₀, Ⅱ₁ and Ⅱ₈ were shown to be the most effective.     

Different tachykinin receptors mediate chloride secretion in the distal colon through activation of submucosal neurones

We investigated the role of tachykinin receptor subtypes on secretory responses in the guinea-pig distal colon using Ussing chamber experiments and intracellular recordings from submucosal neurones. Choline acetyltransferase (ChAT) and vasoactive intestinal polypeptide (VIP) were demonstrated in submucosal neurones by immunohistochemistry. In Ussing chamber experiments substance P (SP), the NK-1-receptor agonist [SAR⁹,Met(O₂)¹¹]-SP and the NK-3-receptor agonist (MePhe⁷)-NKB increased dose-dependently short-circuit currents. The NK-2-receptor agonist (βAla⁸)-NKA(4–10) had no effect. Responses to 1–100 nM SP, [(SAR⁹,Met(O₂)¹¹]-SP and (MePhe⁷)-NKB were tetrodotoxin-sensitive but hexamethonium-insensitive. While (MePhe⁷)-NKB-responses were atropine-sensitive at all concentrations, the atropine sensitivity of the secretory responses to SP and [SAR⁹,Met(O₂)¹¹]-SP dramatically decreased with increasing concentrations. [SAR⁹,Met(O₂)¹¹]-SP and (MePhe⁷)-NKB effects were blocked by the selective NK-1 and NK-3 antagonists CP-99,994–1 (1 μM) and SR 142801 (1 μM), respectively. Combination of both antagonists blocked the SP-response. SR 142801 also suppressed the response to [SAR⁹,Met(O₂)¹¹]-SP. Desensitization with [SAR⁹,Met(O₂)¹¹]-SP significantly decreased (MePhe⁷)-NKB-responses but not vice versa. In intracellular recordings 90% of submucosal neurones were activated by both [SAR⁹,Met(O₂)¹¹]-SP and (MePhe⁷)-NKB as indicated by membrane depolarisation and enhanced spike discharge. These effects were tetrodotoxin-resistant and potentiated by atropine. NK-1- and NK-3-mediated responses occurred equally in ChAT-positive and in VIP-positive neurones. The results suggest the importance of NK-1- and NK-3-receptors on cholinergic and non-cholinergic submucosal neurones for secretory processes in the guinea-pig distal colon. Received: 16 June 1998 / Accepted: 22 September 1998     

化学—酶法立体控制合成光学纯L-羟基苯丙氦酸的新方法

Optically pure L-3(2-hydroxyphenyl) alanine(L-o-tyrosine ,Ⅲa,),L-3-(3-hydroxyphenyl) alanine(L-m-tyrosine,Ⅲb )and L-3-(4-hydroxyphenyl )alanine(L-p-tyrosine,Ⅲc )were synthesized by the stereocontrolled amination of corresponding hydroxycinnamic acld(Ⅱ)catalyzed by L-phenylalanine ammonia-lyase(PAL,EC4.3.1.5 )contained in Rhodoterula rubramycelium. The amination of compound Ⅱ was completed in aqueous ammonia solution( 6.4mol·L^-1,pH10.5, 30℃) with the conversion of 74.9%(Ⅱa),21.1%(Ⅱb)and 20.6%(Ⅱc)respectively.The absolute configuration of the products Ⅲa～c were confirmed by circular dichroism(CD),and chiral high-performance ligand exchange chromatography(HPLEC)showed that productsⅢ were optically pure L-isomers.     

LC-MS/MS法测定人血浆中西酞普兰及其在制剂生物等效性中的应用

A sensitive and selective LC-MS/MS method for determination of citalopram in human plasma was established to study the bioequivalence of different formulations containing citalopram. The samples were simply pretreated by protein precipitation using acetonitrile, and then analyzed on a Zorbax Extend C₈column. The mobile phase consisted of acetonitrile-water-formic acid (60∶40∶0.2), at a flow-rate of 0.5 mL·min^-1. A Thermo Finnigan TSQ Quantum Ultra tandem mass spectrometer equipped with electrospray ionization source was used as detector and was operated in the positive ion mode. Selected reaction monitoring using the precursor to product ion combinations of m/z325 → m/z109 and m/z265 → m/z167 was performed to quantify citalopram and the internal standard, respectively. The pharmacokinetic parameters of citalopram in different formulations were calculated by non-compartment model. The linear calibration curves were obtained in the concentration range of 0.10-100 μg·L^-1. The lower limit of quantification was 0.10 μg·L^-1. The intra- and inter-day relative standard deviation (RSD) over the entire concentration range was less than 5.2%. Accuracy determined at three concentrations (0.25, 8.00 and 90.0 μg·L^-1 for citalopram) ranged from -4.7% to 1.3%. Each plasma sample was chromatographed within 3.0 min. The method was successfully used in bioequivalence study of citalopram in human plasma after oral administration of 20 mg citalopram. Calculated with AUC_{1-120 h}, the bioavailability of two formulations was (102.1±10.9)%. The method is rapid, selective, robust and is proved to be suitable for bioequivalence evaluation of different formulations containing citalopram.     

北京鸭红细胞膜β肾上腺素受体放射配基结合测定法

本文以[³H]dihydroalprenolol([³H]DHA)为放射配基。对北京鸭红细胞(RBC)膜β受体进行了系统研究。结果表明,[³H]DHA与北京鸭RBC结合具有饱和性,肾上腺素能激动剂与[³H]DHA竞争结合的强弱顺序与它们的生物活性一致,提示结合有结构特异性和立体特异性,[³H]DHA与鸭RBC结合迅速、可逆。可见北京鸭RBC膜存在β受体,用于放射配基结合测定有取材方便,受体较丰富,膜蛋白得率高,[³H]DHA非特异结合低和易于保存等优点,可以代替火鸡RBC。     

去甲乌药碱对火鸡红细胞膜β受体及腺苷环化酶活性的影响

本文研究去甲乌药碱(DMC)和异丙肾上腺素(ISO)对火鸡红细胞膜的腺苷环化酶(AC)活性的影响,并用放射配基结合测定法研究了DMC与ISO对β受体的作用。结果表明DMC能激活火鸡红细胞膜上的AC,此作用能被GTP所加强,被心得安(PRO)所阻断。DMC和不同浓度ISO合用,能加强低浓度ISO激活AC活性的作用,而减弱高浓度ISO的效力。DMC和ISO对β受体有相似的亲和力,而DMC的内在活性较小。这些结果直接证明DMC是β受体部分激动剂。     

心得安降压作用与脑内γ-氨基丁酸受体功能的关系

前文报告因中枢经α-肾上腺素受体激动而产生的降压作用有可能是通过γ-氨基丁酸(GABA)能抑制性神经元而实现。鉴于β肾上腺素受体拮抗剂心得安的抗高血压效应已被临床肯定,而且近年又报告心得安引起的降压作用伴有内脏神经放电减少;在几个脑区     

The effects of some β-adrenoreceptor blocking drugs on the uptake and release of noradrenaline by the heart

1. The potencies of some β-adrenoreceptor blocking drugs in reducing noradrenaline uptake by the isolated heart were compared with their potencies in reducing the release of noradrenaline from the heart by tyramine.2. Of the drugs tested, propranolol, pronethalol and dichloroisoprenaline were the most potent in blocking uptake and release of noradrenaline, although none was at potent as cocaine; MJ 1999 and I.C.I. 50172 were only weakly effective.3. Pronethalol and dichloroisoprenaline each reduced release of noradrenaline by tyramine in the concentration range (10^-7-10^-6M) where blockade of responses to tyramine was apparent; with these drugs both reduction of noradrenaline release and β-receptor blockade contribute to the reduction in responses to tyramine.4. Potency of β-receptor blocking drugs in reducing noradrenaline uptake is unrelated to potency in blocking β-receptors; Kö 592 blocks β-receptors without affecting noradrenaline uptake.     

Adrenoceptive receptors in the duodenum,aorta and atria of the rabbit

pA₁₀ values for the α-receptor blocking drug phentolamine against adrenaline, noradrenaline and phenylephrine were determined in rabbit aorta and duodenum, and for the β-receptor blocking drug propranolol, against adrenaline, noradrenaline and isoprenaline in rabbit atria and duodenum. The values for phentolamine against different amines were found to be similar, varying by less than half a log unit, between or within the tissues, as were the values for propranolol. These data provide quantitative evidence that α-receptors in the aorta and duodenum are similar, as are the β-receptors in the atria and duodenum, even though both types of receptor serve divergent functions in different tissues.     

心喘灵(XC-1)及其衍生物XC-2对肾上腺素受体及动脉平滑肌的作用

本文用放射配基结合法研究了心喘灵(XC-1)及其衍生物XC-2对肾上腺素受体的亲和力,用离体器官方法观察了二者对α受体功能的影响,用酶分析法研究了两药对β受体功能的影响。两药各种作用强度相近,对大鼠脑皮层细胞膜α受体有中等强度亲和力(Ki10^-6mol/L),对兔主动脉和大鼠肛尾肌α₁受体均有中等强度阻断作用,但对大鼠输精管突触前α₂受体只有微弱的阻断作用。二药抑制由ISO激动的腺苷酸环化酶活性的IC₅₀均为3.6×10^-5mol/L。此外,二者都能拮抗CaCl₂,KCl和5-HT引起的主动脉条收缩反应并有直接扩张血管的作用。     

Characterization of adenosine deaminase from the malarial parasite, Plasmodium lophurae, and its host cell,the duckling erythrocyte

Adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) was purified and characterized from the malarial parasite, Plasmodium lophurae, and its host cell, the duck (Anas domesticus) erythrocyte, using chromatofocusing (Pharmacia) and adenosine affinity columns. Gel filtration of the enzymes gave molecular weights of 33,800 (P. lophurae) and 36,500 (duck erythrocyte); both enzymes had broad pH optima (pH 6.8 to 8.0), similar stabilities when stored as crude lysates, and like K_m values with adenosine: 2.74 ± 0.88 × 10^?5 M (parasite) and 1.74 ± 0.27 × 10^?5 M (erythrocyte). The P. lophurae adenosine deaminase had a pI of 5.37 ± 0.09, and the duck erythrocyte enzyme had a pI of 4.72 ± 0.09, as determined by chromatofocusing. The parasite enzyme exhibited a specific activity in the crude lysate that was an average 60-fold higher than that of the erythrocyte enzyme. The pattern of elution from the adenosine affinity column, as well as kinetic studies with three adenosine analogs, revealed distinct differences in the binding characteristics of the two enzymes. The P. lophurae adenosine deaminase was weakly retarded by the affinity column, whereas the duck erythrocyte enzyme was strongly retarded. With 9-β-d-arabinosyladenine as substrate, the K_m values were similar (2.29 ± 0.98 × 10^?4 M for P. lophurae and 1.10 ± 0.21 × 10^?4 M for the duck erythrocyte). Erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) was a potent inhibitor of the duck erythrocyte enzyme with 100% inhibition at 1.3 μM, whereas the parasite adenosine deaminase was not inhibited at 422 μM even when incubated for 24 hr. Inhibitor studies with coformycin, a tight-binding inhibitor, resulted in K_i values of 7.14 × 10^?11 M for P. lophurae and 1.86 × 10^?10 M for the duck erythrocyte. The molar equivalencies, E_t, and catalytic numbers, k₃, were slightly different for both enzymes. The E_t values were 2.80 × 10^?10 M (P. lophurae) and 3.13 × 10^?10 M (duck erythrocyte); the k₃ values were 5.18 × 10³ min^?1 and 4.36 × 10³ min^?1 respectively.     

某些四氢异喹啉类生物碱对大鼠脑内多巴胺和5-羟色胺受体的作用

本文报道十二种四氢异喹啉类生物碱对大鼠脑内D-2,5-HT₁和5-HT₂受体的结合特性。其中l-千金藤碱(l-STP)对这三种受体均有较高的亲和力,其Ki值分别为1.7×10^-7,9.4×10^-8和1.8×10^-7mol。l-莲碱(l-REM)对5-HT₂受体的亲和力与Z-STP相似(Ki=1.7×10^-7mol)。THB,THC和THJ对D-2受体的亲和力介于l-SPD和l-THP之间。本文报道的多数生物碱能同时影响两种或两种以上受体部位的结合特性,提示它们对单胺神经系统可能有复杂的相互作用。