多沙唑嗪对映体对兔四种血管α受体的作用

多沙唑嗪(doxazosin，DOX)作为高选择性α₁受体阻断药，是临床上治疗良性前列腺增生(benign prostatic hyperplasia, BPH)的一线药物，但同时引起心血管系统的不良反应。本研究采用兔离体动脉环张力实验及电场刺激兔离体隐动脉诱发交感嘌呤能血管收缩实验观察R-多沙唑嗪(R-doxazosin，R-DOX)和S-多沙唑嗪(S-doxazosin，S-DOX)对兔耳动脉、肠系膜动脉和肺动脉血管平滑肌α₁受体的作用，以及较高浓度R-DOX和S-DOX对兔隐动脉交感神经突触前膜α₂受体的作用。结果表明，在兔耳动脉、肠系膜动脉和肺动脉，R-DOX和S-DOX竞争性拮抗去甲肾上腺素(noradrenaline，NA)诱发的血管收缩反应；其pA₂值分别为7.91±0.03和7.53±0.05，7.80±0.05和7.29±0.07以及8.32±0.06和7.97±0.07；且S-DOX的pA₂值均明显小于R-DOX的pA₂值(P<0.01)。R-DOX和S-DOX(0.1～10 μmol·L^-1)对电刺激诱发的血管收缩反应无明显影响；R-DOX或S-DOX(100 μmol·L^-1)显著抑制电刺激诱发的血管收缩反应，完全抑制外源性NA诱发的血管收缩反应，但对1 mmol·L^-1腺苷三磷酸诱发的血管收缩反应无明显影响。上述结果提示，R-DOX和S-DOX对NA诱发兔耳动脉、肠系膜动脉和肺动脉收缩反应具有竞争性拮抗作用，对上述三种血管S-DOX拮抗NA的pA₂值均明显小于R-DOX。此外，R-DOX和S-DOX的浓度升至10 μmol·L^-1时，对血管交感神经末梢突触前膜α₂受体仍无明显影响。     

二氢石蒜碱对α—受体的阻断作用

二氢石蒜碱(Dihydrolycorine,DL)使新福林增高猫平均动脉压的量-效曲线平行右移,不压低最大反应,使新福林增高毁脊髓大鼠舒张压的量-效反应曲线平行右移,也不压低最大反应。在大鼠肛尾肌和兔主动脉环,DL 拮抗甲氧胺收缩主动脉和肛尾肌的作用其 pA_2值分别为6.35和5.93。但是 DL 对α_2-受体选择性激动剂 B-HT_(920)升高毁脊髓大鼠舒张压的量-效曲线无影响,这些结果提示 DL 可能具有选择性地阻断α_1肾上腺素能受体的作用。     

Disruption of noradrenergic transmission and the behavioural response to a novel environment in NK1R-/- mice

The behaviour of neurokinin-1-receptor gene knockout (NK1R-/-) mice, which lack functional, substance P-preferring receptors, resembles that of NK1R+/+ mice treated with an antidepressant. Because all antidepressants increase central monoamine transmission, we have investigated whether noradrenergic transmission is increased in NK1R-/- mice and, if so, whether this could influence their behaviour. In anaesthetized subjects, the concentration of extracellular noradrenaline in NK1R-/- mice was two-fourfold greater than in NK1R+/+ mice. Systemic administration of the alpha2-adrenoceptor antagonist, 2-(2,3-dihydro-2-methoxy-1,4-benzodioxan-2-yl)-4,5-dihydro-1H-imidazoline (RX 821002), in anaesthetized or freely moving animals increased extracellular noradrenaline in NK1R+/+ mice only. This suggests that the function of alpha2a-autoreceptors, which modulate noradrenergic transmission, is impaired in NK1R-/- mice. Consistent with this, [35S]GTPgammaS binding to activated alpha2a-adrenoceptors was lower (-70%) in the locus coeruleus, but not the frontal cortex, of NK1R-/- mice compared with their NK1R+/+ counterparts. RX 821002-pretreatment, followed by retrodialysis of the noradrenaline reuptake inhibitor, desipramine, into the frontal cortex of anaesthetized mice increased extracellular noradrenaline to the same extent in the two genotypes. Western blots confirmed that there was no difference in the amount of noradrenaline transporter protein in NK1R-/- and NK1R+/+ mice. Finally, the effects of RX 821002 on certain behaviours in a light/dark exploration box were blunted in NK1R-/- mice, but there was no consistent effect on anxiety-like behaviour in the two genotypes. It is concluded that the greater basal efflux of noradrenaline in NK1R-/- mice is explained by increased transmitter release, coupled with desensitization of somatodendritic alpha2a-adrenoceptors. These changes could contribute to the difference in the behavioural phenotypes.     

去甲基肾上腺素和酚妥拉明对豚鼠乳头肌跨膜电位的影响

应用常规玻璃微电极法观察了去甲基肾上腺素、α-受体阻断剂酚妥拉明对豚鼠乳头肌跨膜电位的影响,结果去甲基肾上腺素10~(-7)mol/L对跨膜电位无明显作用,在心得安存在下去甲基肾上腺素可使动作电位时程(APD)延长,酚妥拉明可使跨膜电位APD延长且其效应有浓度依赖性。本实验结果提示,α-受体兴奋可使豚鼠乳头肌APD延长,酚妥拉明对心肌细胞的作用可能不需要通过肾上腺素能机理。     

去甲肾上腺素和酚妥拉明对大鼠肝星状细胞的影响

目的：探讨α-肾上腺素激动剂去甲肾上腺素和拮抗剂酚妥拉明对体外活化的肝星状细胞（HSC-T6）的影响。方法：体外对HSC-T6进行复苏和培养传代;MTT法检测HSC-T6的增殖;放射免疫法检测HSC-T6培养上清液中透明质酸(HA)和III型前胶原（PCIII）的浓度;流式细胞仪检测HSC-T6凋亡率;免疫细胞化学染色检测组织基质金属蛋白酶抑制因子-1(TIMP-1)和基质金属酶-13(MMP-13)蛋白的表达。结果：在体外培养的活化HSC-T6中,去甲肾上腺素（10-5,10-7,10-9 mol&#8226;L-1）能促进细胞增殖,升高分泌HA和PCIII水平,增强TIMP-1蛋白的阳性表达并降低其凋亡率;酚妥拉明（10-5,10-7,10-9 mol&#8226;L-1）能抑制细胞增殖,促进MMP-13的阳性表达并增加HSC-T6的凋亡率。结论：去甲肾上腺素具有促进肝纤维化的作用,酚妥拉明则具有抗纤维化的作用,该作用与其对HSC-T6增殖、凋亡及HA和PCIII分泌水平调控有关。     

Effect of peripheral sympathetic nerve dysfunction on salt sensitivity of arterial pressure

1. Dysregulation of peripheral sympathetic pathways contributes to some forms of salt-dependent hypertension. However, at the present time it is not known whether salt-induced activation of sympathetic nerves or loss of normal sympathoinhibitory responses to salt-induced volume expansion contributes to neurogenic salt-dependent hypertension. The present study was performed to the test the hypothesis that loss of peripheral sympathetic nerve function results in salt-dependent hypertension. 2. The effect of three pharmacological interventions of sympathetic nerve function on the long-term salt-sensitivity of mean arterial pressure (MAP) were measured: (i) blockade of ganglionic transmission with hexamethonium (HEX; n = 5); (ii) destruction of sympathetic nerve terminals with guanethidine (GUAN; n = 7); and (iii) alpha-adrenoceptor blockade with two specific antagonists, namely prazosin (PRAZ; n = 7) and terazosin (TERAZ; n = 8). 3. Mean arterial pressure and heart rate were measured 24 h/day by radiotelemetry in conscious rats during 5 days of normal and 7 days of high (HNa) dietary sodium intake. Despite marked increases in both sodium and water intake during 7 days of the HNa diet, no statistically significant changes in MAP were observed in HEX, GUAN, PRAZ or TERAZ groups. 4. We conclude that loss of peripheral sympathetic neural pathways alone does not cause salt-dependent hypertension in the rat.