Elevation of an endogenous inhibitor of nitric oxide synthase in diabetic rat serum

目的：测定糖尿病大鼠血中内源性ＮＯ合酶抑制物二甲基精氨酸（ＤＭＡ）的含量．方法：在链佐星诱发的糖尿病大鼠测定血清ＤＭＡ的含量和乙酰胆碱（ＡＣｈ）诱导血管内皮依赖性舒张．结果：与对照组相比，糖尿病大鼠ＤＭＡ血清浓度显著增加（５４±１０ｖｓ０７±０３μｍｏｌ·Ｌ－１，Ｐ＜００１）；丙二醛含量也高于对照组（２５±０３ｖｓ１５±０１μｍｏｌ·Ｌ－１，Ｐ＜００１）；糖尿病大鼠ＡＣｈ舒血管效应减弱，其作用可被左旋精氨酸所改善．结论：链佐星诱发糖尿病大鼠高血糖症引起内源性ＤＭＡ含量升高，同时血管内皮依赖性舒张功能被削弱．     

硫酸镁对离体豚鼠心肌细胞钙通道的影响

目的：研究硫酸镁（ＭｇＳＯ）对心肌细胞膜钙离子通道的影响，探讨ＭｇＳＯ４抗心律失常机制。 方法：全细胞膜片箝技术。 结果：细胞外液低镁（０．３ｍｍｏｌ·Ｌ＾－１）使心肌细胞钙电流（ＩＣａ）从１．６±０．６ｎＡ增至１．９±０．４ｎＡ（Ｐ〈０．０５），冲洗后回复至１．７±０．５ｎＡ（Ｐ〈０．０５ｖｓ镁０．３ｍｍｏｌ·Ｌ＾－１，Ｐ〉０．０５ｖｓ台氏液）。ＩＣａ随浓度增高进行性递减；ＭｇＳＯ４４ｍｍｏｌ·     

美西律对海马脑片突触功能缺氧损伤的保护作用

记录大鼠海马脑片ＣＡ１区锥体细胞的群锋电位（ＰＳ）和突触前排放（ＰＶ），缺氧３ｍｉｎ时对照组ＰＳ幅度下降至０．４±０．４ｍＶ，而提前１ｈ灌流美西律（Ｍｅｘ）１０或１００μｍｏｌ·Ｌ＾－１组ＰＳ仅下降至１．２±１．２或１．５±０．４ｍＶ。复氧３０ｍｉｎ后对照组ＰＳ恢复率为１１％，Ｍｅｘ１０或１００μｍｏｌ·Ｌ＾－１组分别为４８％和６５％。可见Ｍｅｘ减慢缺氧时ＰＳ下降过程，加速度复氧时ＰＳ恢复过程，…     

4，5－二氢－6－［（苯乙酰基－哌嗪基）苯基］－5－甲基－3（2H）－哒嗪酮对血小板聚集，花生四烯酸代谢及cAMP含量的影响

４，５－二氢－６－［（苯乙酰基－哌嗪基）苯基］－５－甲基－３（２Ｈ）－达嗪酮（ＳＭＤ。）０．１一２．５ｐｍｏｌ·Ｌ能使血小板激活因子（ＰＡｎ及血栓素Ａ，类似物Ｕ４６６１９诱导的兔血小板聚集剂量一效应曲线不移且最大反应降低。其ｐＤ２分别为６．０±ｓ０．４及６．１±ｓ０．３ＳＭⅡ４还能抑制ＡＤＬ花生四烯酸（ＡＡ）及Ｕ４６６１９诱导的人血小板聚集，其ＩＣ（５０）分别是１２，１３及１．６μｍｏｌ．Ｌ．用放射性薄层层折及放射免疫测定法分别检测血小板ＡＡ代谢产物及ｃＡＭＰ含量表明，ＳＭⅡ４对血小板ＡＡ代谢没有显著影响，但能剂量依赖性地升高血小板内ｃＡＭＰ含量，ＰＡＦμｍｏｌ·Ｌ不能改变此作用     

4,5—二氢—6—[（苯乙酰基—哌嗪基）苯基]—5—甲基—3（2H）—哒…

４，５－二氢－６－［（苯乙酰基－哌嗪基）苯基］－５－甲基－３（２Ｈ）－达嗪酮（ＳＭⅡ４）０．１－２．５μｍｏｌ．Ｌ＾－＾１能使血小板激活因子（ＰＡＦ）及血栓素Ａ２类似物Ｕ４６６１９诱导的兔血小板聚集剂量一效应曲线左移且最大反应降低。其ｐＤ２分别为６．０±ｓ０．４及６．１±ｓ０．３．ＳＭⅡ４还能抑制ＡＤＰ，花生四烯酸（ＡＡ）及Ｕ４６６１９诱导的人血小板聚集，其ＩＣ５０分别是１．２，１．３及１．６．．     

延髓腹外侧头端注射莫索尼定对大鼠血压,心率和肾交感神经放电…

目的：观察延髓腹外侧头端（ＲＶＬＭ）注射莫索尼定（Ｍｏｘ）对麻醉大鼠血压（ＢＰ）、心率（ＨＲ）及肾交感神经放电（ＲＳＮＡ）的影响。方法：麻醉大鼠ＲＶＬＭ注射１μＬ Ｍｏｘ１，１０，１００μｍｏｌ·Ｌ＾－１，同步记录ＢＰ，ＨＲ及ＲＳＮＡ。结果：Ｍｏｘ１，１０，１００μｍｏｌ·Ｌ＾－１分别使ＢＰ从１３．９±１．０ｋＰａ降至１３．０±１．７ｋＰａ（Ｐ〈０．０５），１３．８±１．８ｋＰａ至１１．４±１．５     

络活喜治疗慢性肾功能不全31例临床观察

用氨氯地平（络活喜）对３１例慢性肾功能不全伴高血压患者进行为期３个月的临床观察，治疗后血尿素氮（ＢＵＮ）、血肌酐（Ｓｃｒ）水平明显下降（１６．１±５．３ｖｓ１３．２±６．２ｍｍｏｌ／Ｌ，Ｐ〈０．０５；２５８±６２ｖｓ２２１±８２ｍｍｏｌ／Ｌ，Ｐ〈０．０５）；收缩压和舒张压明显减低（２２．６±０．９ｖｓ９．３±１．６ｋＰａ，Ｐ〈０．０１；１２．７±０．５ｖｓ１０．６±０．８ｋＰａ，Ｐ〈０．０１），同     

细胞外钙离子对培养大鼠交感神经元烟碱受体失敏的影响

以培养的新生大鼠颈上交感节神经元为标本，使用膜片钳全细胞记录技术，观察了细胞外Ｃａ２＋对烟碱受体失敏的影响．发现向神经元喷射１００μｍｏｌ·Ｌ－１ＡＣｈ，可即刻诱发迅速上升的内向电流（ＡＣｈ电流）．随着胞外Ｃａ２＋浓度的上升，ＡＣｈ电流衰减明显加快（Ｐ＜０．０１）．而ＡＣｈ诱发电流的幅度和上升速率则随胞外Ｃａ２＋浓度的上升而显著增加（Ｐ＜０．０１）．当胞外Ｃａ２＋为０，２和６ｍｍｏｌ·Ｌ－１时，ＡＣｈ电流衰减的时间常数分别为８．０±４．３ｓ（ｎ＝９），４．２±０．９ｓ（ｎ＝８）和２．６±０．７ｓ（ｎ＝８）．诱发电流的幅度（ｎＡ）分别为２．０±０．９（ｎ＝９），３．３±１．０（ｎ＝８）和５．１±１．６（ｎ＝８）．其上升速率（ｐＡ／ｍｓ）分别为２．６±０．８和９．３±１．６（ｎ＝８）．以上结果说明，胞外Ｃａ２＋浓度的增加，可加速ＡＣｈ电流的衰减，即加速烟碱受体的失敏，同时提高ＡＣｈ电流幅度，加快烟碱受体离子孔道的开放速率．提示交感神经元烟碱受体上可能存在着不同的Ｃａ２＋结合位点．通过对这些不同位点的作用，Ｃａ２＋可以从两方面影响烟碱受体的功能，进而调制胆碱能神经元的突触传递效率．     

一氧化氮在青霉素致痫中的作用及与NMDA和非NMDA受体的关系

目的阐明一氧化氮（ｎｉｔｒｉｏｘｉｄｅ，ＮＯ）在青霉素致痫中的作用及与ＮＭＤＡ及非ＮＭＤＡ受体的关系。方法用自制的一氧化氮敏感电极——Ｎａｆｉｏｎ－壳聚糖合镍修饰铂电极（Ｎａｆｉｏｎ－ＣＴＳ（Ｎｉ）－Ｐｔ）连续测定了青霉素致痫海马脑片ＣＡ１区锥体层神经元ＮＯ的释放，并同时观察了Ｎ－ｍｅｔｈｙｌ－Ｄ－ａｓｐａｒａｔｅ（ＮＭＤＡ）受体阻断剂ＤＬ－２－ａｍｉｎｏ－ｐｈｏｓｐｈｏ－ｎｏ－ｖａｌｅｒｉｃａｃｉｄ（ＡＰ５）及非ＮＭＤＡ／ＡＭＰＡ受体阻断剂６，７－ｄｉｎｉ－ｔｒｏｑｕｉｎｏｘａｌｉｎｅ－２，３（１ｈ，４ｈ）－ｄｉｏｎｅ（ＤＮＱＸ）对诱发痫波及ＮＯ含量的影响。结果①自制ＮＯ敏感电极检测ＮＯ浓度线性范围为４．５×１０－４～１．０×１０－８ｍｏｌ·Ｌ－１，检测下限为５．０×１０－８ｍｏｌ·Ｌ－１；②青霉素致痫时ＮＯ释放增加，与诱发脑片痫波有剂量反应关系；③ＮＭＤＡ受体阻断剂ＡＰ５（５０μｍｏｌ·Ｌ－１）明显抑制电刺激Ｓｃｈａｆｅｒ＇ｓ纤维引起的ＣＡ１区诱发痫波，表现为痫波数减少，同时伴有ＮＯ释放下降；④非ＮＭＤＡ受体阻断剂ＤＮＱＸ（３μｍｏｌ·Ｌ－１）对诱发痫波作用不明显，ＮＯ释放亦无显著变化；⑤ＡＰ５与一氧化?     

兔蓝斑兴奋引起动脉血压升高

目的：研究电刺激和化学刺激兔蓝斑（ＬＣ）对动脉血压（ＡＰ）和肾交感神经传出活动（ＲＳＡ）的影响。方法：电刺激ＬＣ，ＬＣ微量注射Ｌ－Ｇｌｕ、盐酸吗啡、ＧＡＢＡ、电解毁损ＬＣ，记录ＡＰ和ＲＳＡ。结果：电刺激ＬＣ和ＬＣ注射Ｌ－Ｇｌｕ均引起ＡＰ升高分别为１３．５±０．３ｖｓ１９．５±０．８ｋＰａ和１３．８±０．４ｖｓ１７．５±０．８ｋＰａ）和ＲＳＡ增加。ＬＣ注射吗啡、ＧＡＢＡ对ＡＰ和ＲＳＡ无明显影响。电解     

链佐星所致糖尿病大鼠主动脉内皮依据舒张反应损伤的特征

AIM: To study whether impaired endothelium-dependent relaxation (EDR) in early diabetic mellitus in response to different receptor-mediated and nonreceptor-mediated vasodilators ran parallel and its possible mechanism. METHODS: Isometric tension recording in aortic rings from streptozotocin (Str)-induced diabetic and age-matched nondiabetic rats. RESULTS: EDR induced by receptor agonist acetylcholine (ACh), histamine (His) or bradykinin (BK) were all significantly reduced in diabetic rings compared with control rings, whereas nonreceptor agonist calcimycin-induced EDR was well reserved in diabetic rings [IC50 control: (0.13 +/- 0.07) mumol.L-1 diabetic: (0.14 +/- 0.06) mumol.L-1, P > 0.05, n = 7]. Cyclopiazonic acid (CPA) which also is a nonreceptor mediated endothelium-dependent vasorelaxant and cells' capacitative Ca2+ entry stimulant, failed to trigger EDR in diabetic rings. Pretreatment with N omega-nitro-L-arginine methylester (L-NAME, 0.3 mmol.L-1) not only abolished all of the EDR elicited by above mentioned vasodilators in either of diabetic or control rings, but also leveled responses triggered by each of the agonists between diabetic and control rings. Upon the maximal EDR induced by ACh (1 mol.L-1) or CPA (3 mumol.L-1) in phenylephrine (1 mumol.L-1) precontracted rings, calcimycin (1 mumol.L-1) further relaxed diabetic rings, but contracted control preparations. When endothelium was denuded, relaxation evoked by sodium nitroprusside and contractions triggered by CPA or His were all identical between diabetic and control rings. CONCLUSION: Receptor agonists but not nonreceptor agonists-induced EDR are commonly impaired in 4-wk Str-induced diabetic rat aorta, and this defective effect is attributable to the low formation of EDRF/NO which is related to impaired capacitative Ca2+ entry pathway in endothelium.     

降钙素基因相关肽预适应对溶血磷脂酰胆碱抑制内皮依赖性舒张的…

目的：研究降钙素基因相关肽（ＣＧＲＰ）诱导预适应对溶血磷脂酰胆碱（Ｌｙｓ）抑制内皮依赖性舒张的作用。方法：用苯福林收缩兔与大鼠离体胸主动脉环，观察Ｌｙｓ对乙酰胆碱（ＡＣｈ）所致内皮依赖性舒张的影响。结果：ＣＧＲＰ预处理兔和大鼠离体胸主动脉环显著减轻Ｌｙｓ对ＡＣｈ舒血管效应的抑制，其作用可被蛋白激酶Ｃ（ＰＫＣ）抑制剂Ｈ－７所取消。结论：ＣＧＲＰ诱导预适应对所致内皮细胞损伤具有拮抗作用，此作用与激活Ｐ     

Mechanism underlying enhanced endothelium-dependent vasodilatation in thoracic aorta of early stage streptozotocin-induced diabetic mice

AIM: To investigate the mechanism of the enhanced endothelium-dependent vasodilatation in thoracic aorta of the early stage streptozotocin (STZ)-induced diabetic C57BL/6J mice. METHODS: Radioimmunity was used to detect the metabolite of prostaglandin I2 (PGI2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), in the blood serum. Vascular muscle tension and phenylephrine (PE)-induced rhythmic activity in the isolated thoracic aorta of mice were also compared. RESULTS: 6-Keto-PGF1 alpha in the serum was significantly higher in STZ-induced diabetic mice than age-matched controls [(1.8+/-1.0) microg./L vs (0.5+/-0.3) microg/L, P<0.01]. PE induced rhythmic activity in both diabetic and control mouse aorta but the amplitude was markedly higher in diabetic mice than in controls [(4.9+/-1.7) % vs (12+/-5) %, P<0.01]. PE, high K+ solution-induced contraction, and acetylcholine (ACh)-induced relaxation [(56+/-10) % vs (81+/-8) %, P<0.01] were notably enhanced in diabetic mice than those in controls. Alone NG-nitro-L-arginine methyl ester (L-NAME) or 6-(phenylamino)-5,8-quinolinedione (LY-83583) abolished the rhythmic activity and ACh-induced relaxation in controls but only partially inhibited them in diabetic mice. Indomethacin did not affect rhythmic activity but depressed ACh-induced relaxation. L-NAME plus indomethacin significantly depressed the rhythmic activity and ACh-induced relaxation than L-NAME alone (P<0.01). Furthermore tetraethylammonium plus L-NAME abolished them in diabetic mice. CONCLUSION: The mechanism that enhanced endothelium-dependent vasodilatation in STZ-induced diabetic mice is due to enhanced production of PGI2 and endothelium-derived hyperpolarizing factor (EDHF). The phenomena maybe only take place in early stage of diabetic mice.     

高糖损伤兔主动脉内皮依赖性舒张反应(英文)

目的:研究高糖对兔胸主动脉内皮依赖性舒张反应(EDR)的影响及L-精氨酸、超氧化物歧化酶(SOD)和高糖撤除的作用。方法:以主动脉环EDR为检测指标。结果:高糖可使乙酰胆碱(ACh)诱导的EDR明显受损,高糖撤除24h后不能恢复ACh的舒血管作用,而甘露醇(19.5mmol·L~(-1))不影响血管环EDR。L-精氨酸1mmol·L~(-1)或SOD 150U·L~(-1)可取消高糖对EDR的损伤作用,高糖不影响硝普钠的舒血管作用。结论:高糖可损伤血管EDR,短时间高糖撤除不能逆转,其机制可能与自由基产生及L-精氨酸代谢改变有关。     

野黄芩甙元对糖尿病大鼠主动脉的影响

目的：研究野黄芩甙元对糖尿病大鼠血管合并症的预防作用。方法：利用平滑肌条离体研究装置。结果：在第六周的糖尿病大鼠主动脉：1）乙酰胆碱引起的内膜依赖性舒张作用较对照明显减弱（P＜0．01）;2）苯肾上腺素引起的收缩反应较对照明显增加,最大收缩增加约40％（P＜0．01）;3）糖尿病大鼠服用含0．5％的野黄芩甙元的饮水后,乙酰胆碱引起的内膜依赖性舒张作用较糖尿病组明显增加（P＜0．01）。但是,苯肾上腺素引起的收缩反应增加更显著,最大收缩较对照加约80％（P＜0．01）。结论：野黄芩甙元对糖尿病引起的血管内膜功能损害有防护作用,也可增强苯肾上腺素引起的收缩。     

Ameliorative effect of astaxanthin on endothelial dysfunction in streptozotocin-induced diabetes in male rats

The present study was designed to examine whether astaxanthin (ASX, 3,3-dihydroxybeta, beta-carotene-4,4-dione, CAS 472-61-7), a dietary antioxidant carotenoid that is naturally present in algae, crustaceans, and fish, has a protective effect on endothelial dysfunction of aortas in diabetic rats and the possible molecular mechanism involved. Male Wistar rats were randomly divided into four groups: control rats, diabetic rats, diabetic rats treated with ASX (10 mg/kg/d), and control rats treated with ASX. Type 1 diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ; 60 mg/ kg). STZ-induced diabetes in rats was complicated with excessive oxidative stress and endothelial dysfunction, increased serum oxidized low-density lipoprotein (ox-LDL) and aortic malondialdehyde (MDA) levels, inhibited endothelium-dependent vasorelaxation to acetylcholine (ACh) and unaffected endothelium-dependent vasorelaxation to sodium nitroprusside (SNP). Simultaneously, lectin-like oxLDL receptor-i (LOX-1) expression was enhanced and endothelial nitric oxide (NO) synthase (eNOS) expression was reduced in the aortas of diabetic rats. ASX treatment could significantly decrease serum oxLDL and aortic MDA levels, attenuate blunted endothelium-dependent vasodilator responses to ACh, upregulate eNOS expression, and decrease LOX-1 expression. These results indicated that ASX could ameliorate diabetic endothelial dysfunction by inhibiting the ox-LDLLOX-1-eNOS pathway. Treatment with ASX might be clinically useful for diabetic complications associated with endothelial dysfunction.     

Impaired endothelium-dependent relaxation in isolated resistance arteries of spontaneously diabetic rats.

1. Previous studies have shown that endothelium-dependent relaxation in the aorta of spontaneously diabetic bio bred rats (BB) is impaired. 2. We have investigated noradrenaline (NA) contractility, endothelium-dependent acetylcholine (ACh) and bradykinin (BK) relaxation, and endothelium-independent sodium nitroprusside (SNP) relaxation in mesenteric resistance arteries of recent onset BB rats and established insulin treated BB rats, compared to their age-matched non diabetic controls. 3. There was no significant difference in the maximum contractile response or sensitivity to noradrenaline in either of the diabetic groups compared to their age-matched controls. 4. Incubation with the nitric oxide synthetase inhibitor NG-nitro-L-arginine (L-NOARG) resulted in a significant increase in maximum contractile response to noradrenaline in the recent onset age-matched control group (P < 0.05). Analysis of the whole dose-response curve (using ANOVA for repeated measures with paired t test) showed a significant left-ward shift following the addition of L-NOARG (P < 0.001). A similar but less marked shift (P < 0.01) was evident in vessels from recent onset diabetics. An overall shift in both sensitivity and maximum response was also evident in the age-matched non diabetic controls of the insulin-treated group (P < 0.05). However, by contrast, there was no significant change in sensitivity in the insulin-treated diabetic rats. 5. ACh-induced endothelium-dependent relaxation was significantly impaired in the recent onset diabetic rats compared to their age-matched controls (47 +/- 11% versus 92 +/- 2%, P < 0.05, n = 6), and in the insulin treated diabetic rats (34 +/- 5% versus 75 +/- 6%, P < 0.05, n = 6). The relaxation responses to BK also were significantly impaired in the diabetic rats compared to their age-matched controls (recent onset: 20 +/- 3% versus 72 +/- 7%, P < 0.05, n = 6; insulin treated: 12 +/- 9% versus 68 +/- 7%, P < 0.05, n = 7). 6. Incubation with either the nitric oxide synthetase substrate, U-arginine, or the free radical scavenging enzyme superoxide dismutase (150 mu ml-1) failed to improve the attenuated response of acetylcholine-induced relaxation in the diabetic vessels. 7. Endothelium-dependent relaxation mediated by ACh and BK was significantly attenuated in both the diabetic and control vessels after incubation with L-NOARG. 8. Pretreatment with a cyclo-oxygenase inhibitor, indomethacin, significantly enhanced the relaxation to ACh in both the recent onset and insulin treated diabetic rats (42 +/- 10%, n = 7 versus 64 +/- 7%, n = 7, P < 0.05, and 40 +/- 5%, n = 7 versus 65 +/- 9%, n = 6, P < 0.05). 9. Following endothelium removal, there was a marked impairment in endothelium-dependent relaxation responses to ACh and BK in both the diabetic and control vessels. 10. Incubation with the thromboxane A2 receptor antagonist SQ29548, did not significantly improve the ACh endothelium-dependent relaxation response in the diabetic vessels. 11. Endothelium-independent relaxation to sodium nitroprusside was significantly impaired in the first group of diabetic vessels studied; however, subsequent studies showed no impairment of the sodium nitroprusside response in the diabetic vessels. 12. In conclusion, the ability of the endothelium to regulate vascular contractility is reduced in recent onset diabetic vessels, and significantly impaired in established insulin treated diabetics. Relaxation to the endothelium-dependent vasodilators ACh and BK was impaired in both the recent onset and the established insulin treated diabetics, and the ACh response was significantly improved following pretreatment with indomethacin, suggesting a role for a cyclo-oxygenase-derived vasoconstrictor. Preliminary studies with a thromboxane A2, receptor antagonist, SQ29548 did not significantly improve the impaired relaxation to ACh, indicating that the vasoconstrictor prostanoid is not thromboxane A2.     

山莨菪碱对乙酰胆碱诱导的猫离体动脉内皮依赖性舒张反应的影响(英文)

目的　观察山莨菪碱对乙酰胆碱 (ACh)诱导的内皮依赖性血管舒张反应的影响。方法　采用猫离体血管功能实验 ,观察山莨菪碱对ACh诱发的内皮依赖性血管舒张反应的影响。结果　在猫肠系膜动脉、肾动脉和股动脉 ,山莨菪碱 0 .0 1～ 1 .0nmol·L-1 能够浓度依赖地抑制ACh诱导的内皮依赖的血管舒张反应。山莨菪碱抑制 1 0 μmol·L-1 ACh所诱导血管舒张的IC50 分别为 0 .2 36 ,0 .72 9和 0 .50 8nmol·L-1 ,山莨菪碱的拮抗作用符合非竞争性拮抗模式。此外 ,1 0nmol·L-1 山莨菪碱能有效拮抗ACh诱导的冠状动脉内皮依赖性舒张反应。结论　山莨菪碱能强效拮抗ACh诱发的内皮依赖性血管舒张反应 ,这种效应具有组织特异性的特点。     

6β—乙酰氧基去甲托烷对人和豚鼠呼吸道的收缩作用

AIM: To study the effects of 6 beta-acetoxy nortropane (6 beta-AN) on the isolated human bronchus and guinea pig trachea. METHODS: The contractile effect of 6 beta-AN was studied with 4 different muscarinic receptor antagonists on airway strips and inositol phosphates (IP) accumulation in human bronchi was determined by HPLC with radioactivity flow detector. RESULTS: (1) The maximal contractile effect of 6 beta-AN was lower than that of acetylcholine (ACh) on the human bronchus and equal to that of ACh on the guinea pig trachea. 6 beta-AN was more potent than ACh on both preparations (68 and 245 times, respectively). (2) The contractile effect of 6 beta-AN was inhibited by atropine (1 -100 nmol.L-1) or para-fluoro-hexahydro-sila-difenidol (0.01-1 mumol.L-1), but not by methoctramine (Met, 0.3-3 mumol.L-1) or pirenzepine (0.01-0.1 mumol.L-1), and was not enhanced by tacrine (0.1-10 mumol.L-1) or by epithelium removal. (3) The 6 beta-AN induced-contraction was accompanied by an increase of IP levels in isolated human bronchial tissues. (4) 6 beta-AN had an inhibitory effect on isoprenaline (Iso)-induced relaxation, which was abolished or reduced by Met 0.3 mumol.L-1. CONCLUSION: 6 beta-AN exerts a potent contractile effect involving muscarinic M3 receptor stimulation on airway smooth muscle. Muscarinic M2 receptor stimulation is furthermore partially involved in the antagonism by 6 beta-AN on the Iso-induced relaxation of the guinea pig trachea.