左旋千金藤啶碱对外周血管多巴胺DA_1和DA_2受体亚型的作用

用家兔离体血管环方法，研究左旋千金藤啶碱（ｌＳＰＤ）对外周血管ＤＡ１和ＤＡ２受体亚型的作用。结果表明，ｌＳＰＤ使ＤＡ１受体激动剂ＦＯＤＡ诱发的肾、肺和肠动脉以及ＤＡ２受体激动剂ＰＢＤＡ诱发的肠和股动脉舒张反应的量效曲线非平行右移，最大反应（Ｅｍａｘ）降低，均呈非竞争性拮抗；ｌＳＰＤ本身还可使肾和肺血管产生轻度的浓度依赖性舒张反应，表现为ＤＡ１受体激动剂的作用特性。提示ｌＳＰＤ为外周血管ＤＡ１和ＤＡ２受体的混合性阻滞剂并兼有ＤＡ１受体部分激动剂的双重作用特性。     

Effects of long-term application of dopamine HCl on dopamine agonist-induced cAMP production in rat renal cortex

目的：观察长期给予盐酸多巴胺对大鼠肾皮质多巴胺受体亚型所介导的腺苷酸环化酶活性的影响．方法：用放免分析法测定ｃＡＭＰ含量，作为反映多巴胺受体功能的指标．结果：长期给予盐酸多巴胺可显著减少肾皮质由非诺多泮引起的ｃＡＭＰ增加的量和在Ｓｃｈ２３３９０存在下由ＰＢＤＡ引起的ｃＡＭＰ降低的量，但其变量百分比则与对照组无显著差异．Ｓｃｈ２３３９０可阻断由非诺多泮和ＰＢＤＡ引起的ｃＡＭＰ的增加，而多潘立酮可阻断在Ｓｃｈ２３３９０存在下由ＰＢＤＡ引起的ｃＡＭＰ的降低．结论：长期应用多巴胺可使大鼠肾皮质的ＤＡ１和ＤＡ２受体均发生明显的“下调”，但余留受体的反应性不变．     

非诺多泮和PBDA对兔冠状动脉和肾动脉cAMP产生系统影响的对比研究

目的　研究多巴胺 1(DA1)及多巴胺 2 (DA2 )受体激动剂对兔冠状动脉及肾动脉腺苷酸环化酶 (AC)活性的影响。方法　用放射免疫分析法测定cAMP含量 ,作为反映多巴胺受体功能的指标。结果　DA1受体激动剂非诺多泮(fenoldopam)及DA2 受体激动剂PBDA均可剂量依赖性增加冠状动脉及肾动脉cAMP的生成量。肾动脉cAMP的生成量均显著高于冠状动脉cAMP的生成量 ,选择性DA1受体阻断剂SCH2 3 390能够阻断fenoldopam及PBDA所引起的cAMP生成量的增加 ,而DA2 受体阻断剂domperidone则对PBDA的这一作用没有影响。结论　兔肾动脉及冠状动脉上都存在有剌激AC活性的DA1受体 ,但冠状动脉DA1受体的位点数比肾动脉DA1位点数要少得多 ,从而提示冠状动脉DA1受体的作用比肾动脉要弱     

丙基丁基多巴胺对心肌内向整流钾电流的抑制作用(英文)

研究丙基了基多巴胺（ＰＢＤＡ）对内向整流钾电流（Ｉｋ１）的影响．方法：应用缓慢斜坡去极化脉冲程序测定离体豚鼠心室肌细胞准稳态电流－电压关系曲线．结果： ＰＢＤＡ ５, ５０和１００μｍｏｌ· Ｌ－１浓度依赖性地降低了心肌内向整流钾电流,表明该药对Ｉｋ１具有抑制作用ＰＢＤＡ对于Ｉｋ１的这种抑制效应不被多巴胺Ｄ２受体选择性阻断剂多潘立酮所阻断．结论：ＰＢＤＡ直接抑制Ｉｋ１,与多巴胺Ｄ２受体无关。     

脊髓中PK－C激动剂佛波醇酯和抑制剂他莫昔芬引起的心血管效应

给清醒大鼠脊髓蛛网膜下腔注射（ｉｔｈ）不同剂量的ＰＫＣ激动剂佛波醇酯（ＴＰＡ）后，平均动脉压（ｍＡＢＰ）呈明显剂量效应关系的上升，但心率（ＨＲ）无明显改变。不同剂量的ＰＫＣ抑制剂他莫昔芬（ｔａｍｏｘｉｆｅｎ）则使ｍＡＢＰ下降，亦有量效关系。给大鼠ｉｔｈ不同剂量二丁酰环磷酸腺苷（ＤＢｃＡＭＰ）也引起加压效应，并使ＨＲ减慢。在有效剂量（２．５μｇ·μｌ－１）的ＤＢｃＡＭＰ作用下，ＴＰＡ的加压效应可得到明显的增强。     

多巴胺D_1和D_2受体拮抗剂对乙醇引起大鼠纹状体抗坏血酸释放的影响

应用脑内透析技术结合高效液相色谱电化学检测研究了多巴胺Ｄ１和Ｄ２受体拮抗剂对乙醇引起大鼠纹状体抗坏血酸（ＡＡ）释放的影响。乙醇（３．０ｇ·ｋｇ－１,ｉｐ）显著增加纹状体抗坏血酸释放,高于基础水平的２００％左右。多巴胺Ｄ２受体拮抗剂舒必利（２００ｍｇ·ｋｇ－１,ｉｐ）能显著拮抗乙醇引起的纹状体ＡＡ释放,而Ｄ１受体拮抗剂ＳＣＨ２３３９０（０．５,１．０ｍｇ·ｋｇ－１,ｓｃ）则能协同增加其释放。非选择性多巴胺受体拮抗剂氯丙嗪、氟哌啶醇、氯波必利对纹状体ＡＡ基础释放及乙醇引起纹状体ＡＡ释放均无显著影响。联合使用舒必利（１００ｍｇ·ｋｇ－１,ｉｐ）和ＳＣＨ２３３９０（０．５ｍｇ·ｋｇ－１,ｓｃ）对乙醇引起的纹状体ＡＡ的释放也无影响。此结果提示,多巴胺Ｄ１受体和Ｄ２受体的阻断对乙醇引起的大鼠纹状体ＡＡ释放具有相反的调节作用。     

Effects of tetrahydroprotoberberines on dopamine D_2 receptors in ventral tegmental area of rat

阐明四氢原小檗碱同类物（ＴＨＰＢ）对大鼠中脑腹侧被盖区（ＶＴＡ）多巴胺（ＤＡ）受体的作用特性，并比较它们的作用强度．方法：采用大鼠在体胞外单位放电记录．结果：观察了１１个ＴＨＰＢ均可完全地翻转ＤＡ受体激动剂阿扑吗啡（２０μｇ·ｋｇ－１）所产生的放电抑制作用，为Ｄ２受体拮抗剂的作用特性．ＴＨＰＢ对Ｄ２受体的作用与Ｃ２位上的ＯＨ基团有密切的关系．它们的作用强度（ＥＤ５０，μｇ·ｋｇ－１）：ＴＨＰＢ１４３（５６）＞ＳＰＤ（８５）＞Ｉｓｏ（１７０）＞ＴＨＰ（３３）＞ＴＨＢ（４８）＞ＴＨＰＢ１８（６６）＞ＴＨＰＢ１（１７９）＞ＴＨＰＢ１９（４０８）＞ＴＨＰＢ１２６（５１０）＞ＴＨＰＢ１０４（１０１９）＞ＴＨＰＢ１０（４８１５）．结论：１１个ＴＨＰＢ均为ＶＴＡＤ２受体拮抗剂，以Ｃ２位上有ＯＨ基团的ＴＨＰＢ１４３作用最强．     

培高利特对黑质多巴胺神经元放电活动的激动作用

研究Ｄ２受体激动剂培高利特（Ｐｅｒｇｏｌｉｄｅ，Ｐｅｒ）对大鼠黑质多巴胺（ＤＡ）神经元放电活动的影响，并与溴陷亭（ｂｒｏｍｏｃｒｉｐｔｉｎｅ，Ｂｒｏ）作比较，同时验证Ｐｅｒ在整体动物有无Ｄ１激动剂性质。胞外单细胞电活动记录技术。二个药物均能抑制敏感及不敏感的ＤＡ神经元自发放电活动。     

三种阿片受体激动剂对突触传递的抑制作用

目的：比较不同浓度三种阿片受体激动剂对突触传递的抑制作用．方法：用细胞内记录和细胞外微电泳技术，于大鼠伏核脑片制备上记录神经元的兴奋性突触后电位和谷氨酸钠所致细胞膜去极化．结果：（ＤＡｌａ２，ＮＭｅＰｈｅ４，Ｇｌｙｏｌ）ｅｎｋｅｐｈａｌｉｎ（ＤＡＧＯ），（ＤＰｅｎ２，５）ｅｎｋｅｐｈａｌｉｎ（ＤＰＥＮ），ａｎｄｔｒａｎｓ（±）３，４ｄｉｃｈｌｏｒｏＮｍｅｔｈｙｌＮ［２（１ｐｙｒｏｌｉｄｉｎｙｌ）ｃｙｃｌｏｈｅｘｙｌ］ｂｅｎｚｅｎｅａｃｅｔａｍｉｄｅｍｅｔｈａｎｅｓｕｌｆｏｎａｔｅ（Ｕ５０４８８Ｈ）（１μｍｏｌ·Ｌ－１）均降低突触传递，尤以ＤＡＧＯ抑制作用最著．结论：三种阿片受体激动剂对突触传递的抑制作用均具有浓度依赖性，其作用机制与谷氨酸介导的突触传递受抑制有关．     

大鼠伏膈核内多巴胺受体与电针镇痛的关系

目的：研究多巴胺受体拮抗剂左旋四氢巴马汀（ｌ－ＴＨＰ）加强电针镇痛（ＥＡＡ）的原理，阐明中枢神经系统内多巴胺（ＤＡ）系统在ＥＡＡ中的作用，方法：分别将Ｄ１受激动剂ＳＫ＆Ｆ－３８３９３和Ｄ２受体激动剂ｑｕｉｎｐｉｒｏｌｅｈｙｄｒｏｃｈｌｏｒｉｄｅ（Ｑｕｉ）注射入大鼠伏膈核，观察对ＥＡＡ及ｌ－ＴＨＰ加强ＥＡＡ的作用。结果：ＳＫ＆Ｆ－３８３９３（５μｇ，１０μｇ）明显对抗ｌ－ＴＨＰ加强ＥＡＡ的作用，１０     

Relative DA1-dopamine-receptor agonist and alpha-adrenoceptor antagonist activity of fenoldopam in the anesthetized dog

Relative DA1-dopamine-receptor agonist and alpha-adrenoceptor antagonist activities of fenoldopam were determined in pentobarbital anesthetized dogs. The renal vasodilating effect of intravenous infusions of fenoldopam was used as an index of its DA1-agonist activity. Inhibition by fenoldopam of femoral vasoconstriction produced by intraarterial administration of phenylephrine (a relatively selective alpha 1 agonist) and UK 14,304 ( a relatively selective alpha 2 agonist) was used to determine its alpha-adrenoceptor antagonist activity. Intravenous infusions of 0.1 and 0.2 microgram/kg/min of fenoldopam caused dose-related reductions in renal vascular resistance and mean arterial pressure. Higher rates of infusions of fenoldopam (2 and 5 micrograms/kg/min) were given after pretreatment with 50 micrograms/kg/min SCH 23390 (a DA1-selective antagonist) to attenuate DA1-mediated hemodynamic effects. After SCH 23390, the infusion of 5 micrograms/kg/min of fenoldopam produced approximately the same hypotensive and renal vasodilating actions as the 0.2 microgram/kg/min infusion without SCH 23390. Alpha-adrenoceptor blocking activity was not observed with the 0.1, 0.2, and 2 micrograms/kg/min infusions of fenoldopam. The 5 micrograms/kg/min infusion, however, produced 14 and 25% inhibition of the vasoconstrictor effects of phenylephrine and UK 14,304, respectively. These data indicate that fenoldopam decreases renal vascular resistance in doses which are 25 to 50 times less than the dose needed to antagonize alpha adrenoceptors.     

Lack of effect of lithium on the renal response to DA1-dopamine receptor stimulation by fenoldopam in normal man.

1. The effect of oral lithium (300 mg) on the renal response to the selective DA1-dopamine receptor agonist fenoldopam was investigated in seven normal men. Lithium had no influence on sodium excretion and renal haemodynamics during fenoldopam infusion. The fenoldopam-induced rise in PRA was enhanced in the presence of lithium. We conclude that a previously described interaction between lithium and the dopamine agonist gludopa is not mediated by DA1-dopamine receptors or is confined to higher doses of lithium.     

左旋千金藤啶碱对外周血管多巴胺DA1和DA2受体亚型的作用

用家兔离体血管环方法,研究左旋千金藤啶碱(l-SPD)对外周血管DA₁和DA₂受体亚型的作用。结果表明,l-SPD使DA₁受体激动剂FODA诱发的肾、肺和肠动脉以及DA₂受体激动剂PBDA诱发的肠和股动脉舒张反应的量效曲线非平行右移,最大反应(Emax)降低,均呈非竞争性拮抗;l-SPD本身还可使肾和肺血管产生轻度的浓度依赖性舒张反应,表现为DA₁受体激动剂的作用特性。提示l-SPD为外周血管DA₁和DA₂受体的混合性阻滞剂并兼有DA₁受体部分激动剂的双重作用特性。     

The action of a dopamine (DA1) receptor agonist, fenoldopam in human vasculature in vivo and in vitro.

This study was designed to investigate dopaminergic mechanisms in human vasculature using the selective vascular dopamine receptor agonist fenoldopam in vivo and in vitro. In vivo, forearm blood flow was measured plethysmographically and in vitro isolated rings of human blood vessels from a variety of sites were used for tissue bath studies. Intra-arterial fenoldopam markedly increased forearm blood flow, this effect was antagonised by (R) sulpiride, a vascular dopamine (DA1) antagonist, but not by metoclopramide, a neuronal (DA2) antagonist, or by guanethidine, an adrenergic neurone blocking agent. In vitro, fenoldopam relaxed preconstricted human renal, mesenteric and lumbar arteries, but not saphenous vein in a concentration dependent manner. (RS) sulpiride and SCH 23390 competitively antagonised this effect. These studies demonstrate the presence of a vasodilatory vascular dopamine receptor in man both in vivo and in vitro.     

Dopamine receptors in the stellate ganglion of the dog

Effects of fenoldopam, a selective DA1 dopamine receptor agonist, and dipropyl dopamine and propylphenethyl dopamine, preferential DA2 dopamine receptor agonists, on ganglion transmission were studied in pentobarbital-anesthetized, open-chest dogs. Tachycardia induced by electrical stimulation (supramaximal voltage, 0.5 ms duration, 1-2 Hz) of the preganglionic cardio-accelerator nerves was monitored as a measure of ganglionic transmission. Drugs were injected into the costocervical artery (i.a.) close to the arterial supply of the ganglion. Doses required to produce 30-40% inhibition of ganglionic transmission by the i.a. route were 2-8 micrograms for dipropyl dopamine, 4-16 micrograms for propylphenethyl dopamine, and 100 micrograms for fenoldopam. At these doses none of the agonists affected tachycardia induced by electrical stimulation of the postganglionic nerve. Domperidone (5 micrograms/kg i.v.), a selective DA2 dopamine receptor antagonist, markedly antagonized the effects of dipropyl dopamine and propylphenethyl dopamine, but had only minor (and statistically insignificant) effects on the inhibitory effect of fenoldopam. SCH 23390 (5 micrograms/kg i.v.), a selective and potent DA1 antagonist, failed to modify the effects of any of the agonists. In a separate series, infusion of fenoldopam, 20 micrograms/kg per min i.v. for 5-7 min, facilitated postganglionic nerve stimulation and blocked the inhibitory effect of UK 14,304, an alpha 2-adrenoceptor agonist, on the postganglionic nerve. These results confirm and support the presence of DA2 but do not support the presence of the prototypal DA1 dopamine receptor in the mammalian ganglia. Furthermore, the alpha 2-adrenoceptor blocking property of fenoldopam points to the complication of using i.v. administration for studying its ganglionic actions while monitoring the target tissue effects in response to preganglionic nerve stimulation.     

Do renal tubular dopamine receptors mediate dopamine-induced diuresis in the anesthetized cat?

The aim of this study was to investigate whether the pentobarbitone anesthetized cat is a suitable preparation in which to characterize renal tubular dopamine receptors. Intravenous infusion of dopamine (10-100 micrograms/kg/min) resulted in a dose-related increase in mean blood pressure (MBP), urine output, sodium excretion (UNaV), and fractional sodium excretion (FENa). This diuretic effect occurred despite little change in glomerular filtration rate, suggesting that it is a consequence of decreased tubular reabsorption. Dopamine (10-100 micrograms/kg/min, i.v.) also induced marked dose-related falls in renal vascular conductance; however, renal blood flow was not significantly reduced. The increases in MBP, urine output, UNaV, and FENa induced by dopamine (10-100 micrograms/kg/min, i.v.), were unaffected by pretreatment of cats with either the selective dopamine DA1 or DA2 receptor antagonists, SCH 23390 (30 micrograms/kg, i.v.), or domperidone (100 micrograms/kg, i.v.) respectively. In contrast, pretreatment of cats with the nonselective alpha-adrenoceptor antagonist, phentolamine (1 mg/kg, i.v.) prevented dopamine-induced increases in urine output and MBP. Infusion of the selective dopamine DA1 receptor agonist fenoldopam (0.01-10 micrograms/kg/min) into the left renal artery failed to increase left renal vascular conductance, or left kidney urine output, UNaV, or FENa. In conclusion, this study provides no evidence for the involvement of renal tubular dopamine receptors in dopamine-induced diuresis in anesthetized cats. Rather, the diuretic effect appears to be linked to stimulation of alpha-adrenoceptors.     

Preclinical and clinical studies on the cardiovascular and renal effects of fenoldopam: A DA-1 receptor agonist

Recent research in the area of peripheral dopamine (DA) receptors has led to the identification of two distinct subtypes of DA receptors, activation of which results in marked changes in the cardiovascular and renal function consisting of hypotension, bradycardia, diuresis, and natriluresis. Peripheral DA receptors mediating these effects are subdivided into DA-1 and DA-2 subtypes. The development of selective DA-1 and DA-2 receptor agonists and antagonists has made it possible to furhter characterize DA receptors located at various sites within the cardiovascular system. It is now established that activation of DA-1 receptors located on blood vessel produces vasodilation, whereas stimulation of DA-2 receptors on postganglionic sympathetic nerves results in the inhibition of norepinephrine release. The renal effects of DA receptor agonists either involve activation of specific DA receptors at various sites in the kidney and/or result from renal hemodynamic changes produced by these compounds. The concept of developing selective DA receptor agonists as therapeutic agents in the treatment of cardiovascular disorders has been proposed by several investigators. Fenoldopam (SK&F 82526) represents one of these new orally active DA receptor agonists developed for potential use in the treatment of hypertension and ischemic renal disease. In animal experiments fenoldopam was shown to produce hypotension and increase renal blood flow. It produced natriuresis and diuresis, and these effects were due to the activation of DA-1 receptors. Recent clinical studies show that fenoldopam decreases blood pressure and renal vascular resistance and causes diuresis and natriuresis in hypertensive patients. The antihypertensive action of fenoldopam is mediated by a decrease in total peripheral resistance. There are increases in heart rate and plasma renin activity in hypertensive patients. Fenoldopam also improves left ventricular performance in patients suffering from congestive heart failure. These initial studies with fenoldopam show that peripheral DA-1 receptor stimulation may represent an effective approach in the treatment of cardiovascular diseases. Future research in this area should be aimed toward developing DA-1 receptor agonists that have longer duration of action and do not evoke renin release, while maintaining the beneficial effects on the kidney.     

Anatomical localization of the binding and functional characterization of responses to dopexamine hydrochloride in the rat mesenteric vasculature.

Dopamine receptors of the DA1 subtype have been identified in mesenteric blood vessels, stimulation of which leads to vasodilation. In this study, we have determined the anatomical localization of dopexamine-hydrochloride-binding sites and carried out functional characterization of responses to this DA1-receptor and beta 2-adrenoceptor agonist in rat mesenteric vasculature. Autoradiographic studies showed the presence of [3H]-dopexamine-binding sites in all the different layers of the mesenteric artery. The DA1 receptor antagonist, SCH 23390 (IC50 = 4.9 mumol/l), and the beta-adrenoceptor antagonist, propranolol (IC50 = 6.0 mumol/l), inhibited the binding of dopexamine. The inhibitory effect of these compounds on dopexamine binding was selective for different regions of the mesenteric artery. Also, dopexamine produced concentration-related increases in cAMP formation in membrane particles from superior mesenteric artery and its main branches. The presence of both SCH 23390 and propranolol was required to completely abolish dopexamine-induced increases in cAMP formation. In functional studies, dopexamine (1 and 3 micrograms/kg/min) produced dose-related increases in mesenteric blood flow (23 and 38%, respectively) which were accompanied by concomitant decreases in the calculated mesenteric vascular resistance. As seen with increases in cAMP, the vascular responses to dopexamine could be completely abolished only by prior treatment with both SCH 23390 and propranolol. These results suggest that in mesenteric vasculature of rat dopexamine binds primarily to DA1 receptors and beta 2-adrenoceptors. The activation of these receptors by dopexamine leads to vasodilation which is mediated by an increase in the intracellular levels of cAMP.     

Influence of the dopamine receptor agonists fenoldopam and quinpirole in the rat superior mesenteric vascular bed.

The effect of local administration of the dopamine 2 (DA2)-receptor agonist quinpirole and of the DA1-receptor agonist fenoldopam was studied in the in situ, constant flow autoperfused, superior mesenteric vascular bed of the rat. Local infusion of quinpirole (30 micrograms kg-1 min-1 for 5 min) had no effect on baseline perfusion pressure; it reduced the pressor responses to electrical stimulation (4 Hz, 1 ms, supramaximal voltage) of the periarterial sympathetic nerves to 45.6 +/- 2.1% of its original value but did not modify similar pressor responses produced by locally administered noradrenaline. The inhibitory effect of quinpirole was antagonized by the selective DA2-receptor antagonist domperidone (10 micrograms kg-1) but not by the selective DA1-receptor antagonist SCH 23390 (50 micrograms kg-1). Local infusion of fenoldopam (30 micrograms kg-1 min-1 for 5 min) reduced baseline perfusion pressure to 89.9 +/- 1.9%, increased the pressor response to electrical stimulation (4 Hz, 1 ms, supramaximal voltage) of the periarterial nerves to 134.7 +/- 14.0%, but reduced the pressor response to locally administered noradrenaline to 37.2 +/- 8.2%. Similar pressor responses induced by the selective alpha 1-adrenoceptor agonist phenylephrine were also reduced by fenoldopam (to 38.4 +/- 6.4%), but responses to locally administered angiotensin II were not modified. Pretreatment with SCH 23390 (50 micrograms kg-1) antagonized the effect of fenoldopam on baseline perfusion pressure, but had no influence on the effect of fenoldopam on responses to electrical stimulation or to noradrenaline. Pretreatment with the selective alpha 2-adrenoceptor antagonist rauwolscine (100 micrograms kg-1) had no effect on the reduction in baseline perfusion pressure induced by fenoldopam nor on its inhibitory effect on the response to noradrenaline, but it antagonized the stimulatory effect of fenoldopam on the response to electrical stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)