Sodium Nitroprusside Enhances Contractions of the Guinea-pig Isolated Vas Deferens

The effects of sodium nitroprusside on the electrical and mechanical properties of the smooth muscle of the guinea-pig vas deferens, and its responses to transmitter substances, have been investigated by use of the sucrose-gap technique. Isolated longitudinal segments of guinea-pig vas deferens contracted in response to electrical field stimulation (100 V, 0.04–0.1 ms, 1–5 Hz, 10 s train every 60 s) and application of ATP (1 mM) or noradrenaline (10 μM). Sodium nitroprusside (0.1 mM) did not affect resting tension but did enhance contractions evoked by electric-field stimulation but not by ATP or noradrenaline. The sodium nitroprusside-induced enhancement was unaffected by the nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) (0.1 mM). Conversely, electrically evoked contractions were unaffected by the nitric oxide precursor L-arginine (1 mM) or the nitric oxide donor S-nitroso-N-acetyl-DL-penicillamine (SNAP) (0.1 mM). The amplitudes of electrically evoked excitatory junction potentials (EJPs) were not affected by application of sodium nitroprusside, although it caused a small depolarization of 0.7 ± 0.3 mV. Similarly, the depolarization caused by exogenous application of ATP or noradrenaline was unaffected by the presence of sodium nitroprusside. L-NAME, L-arginine and SNAP did not affect EJP amplitude or baseline membrane potential. It is concluded that sodium nitroprusside enhances electrically evoked contractions of the guinea-pig vas deferens by reducing the threshold voltage for action potential firing in smooth-muscle cells.     

The Response of the Circular Muscle Layer of the Guinea-Pig Isolated Vas Deferens to Transmural Electrical Stimulation

1 Four preparations are described for the isolation of the response of the circular muscle of the guinea-pig vas deferens. These are the `Furchgott' strip, the `Vane' strip, the chain preparation and the perfused preparation.

2 The four preparations were stimulated transmurally with pulses of supramaximal voltage. The threshold pulse width to which the strips and the perfused preparation responded was 0.025 ms and the maximum responses occurred at 0.1 ms. The threshold frequency was 2 Hz for strip and perfused preparations, the maxima being 20 or 50 Hz for strip preparations and 100 Hz for perfused preparations. The effect of varying the number of pulses per train was also investigated on the perfused vas. Responses occurred to train lengths of 8, 16, 32, 128 pulses, the maximum response being given at 128 pulses at 100 Hz; 256 pulses per train did not produce a further increase in response. The perfused preparation exhibited an after-response at certain frequencies and train lengths.

3 Tetrodotoxin and the local anaesthetics, procaine and lignocaine, reversibly abolished the responses of strip and perfused preparations to transmural stimulation.

4 The response to intramural nerve fibre stimulation was abolished by guanethidine or bethanidine; this abolition was reversed by dexamphetamine. Noradrenaline contracted strip preparations of circular muscle and raised the pressure in perfused preparations; noradrenaline was competitively antagonized by thymoxamine. The major part of the motor innervation of the circular layer seems to be noradrenergic.

     

Pharmacological Characterization of the Vanilloid Receptor in the Rat Isolated Vas Deferens

The present study set out to further characterize the vanilloid receptor in the rat isolated vas deferens. In this preparation, both capsaicin and resiniferatoxin (RTX) evoked a concentration-dependent inhibition in the amplitude of electrically-evoked contractions with pEC50 values of 7.62 ± 0.03 and 12.2 ± 0.21 respectively. Responses to capsaicin were fast in onset and faded rapidly over a 30-min exposure period, whereas those to RTX were slow in onset and well maintained, an observation believed to reflect pharmacokinetic differences in the rate of penetration to the vanilloid receptor. Responses to both agonists showed mutual cross-desensitization and were antagonized by both the vanilloid-receptor antagonist capsazepine and the ion-channel blocker ruthenium red. The capsaicin analogue, olvanil failed to either mimic or antagonize capsaicin-evoked responses in the rat isolated vas deferens, an effect at variance with previous observations in other tissues. The reason for these differences is unclear, but the possibility of multiple classes of receptor cannot at this stage be ruled out.     

Involvement of σ-Receptors in the Increase in Contraction of Mouse Vas Deferens Induced by Exogenous ATP

The effects of σ-receptor ligands on the twitch contraction elicited by the exogenous application of adenosine 5′-triphosphate (ATP) in the unstimulated mouse vas deferens were studied. (-)-Pentazocine, 1,3?di(2?tolyl)guanidine (DTG) and two pairs of optical isomers of 3?(3?hydroxyphenyl)-N-(1?propyl)piperidine (3?PPP) and N-allylnormetazocine (SKF?10,047) potentiated the exogenous application of ATP-induced twitch-type contraction in a concentration-dependent manner, while (+)-pentazocine did not affect it. The order of potentiating ability was: (+)?3?PPP>(-)-pentazocine>(-)-SKF?10,047> DTG>(-)?3?PPP>(+)-SKF?10,047. On the other hand, haloperidol and rimcazole, putative σ-receptor antagonists, suppressed this twitch contraction. In addition, these antagonists significantly blocked the (+)-3?PPP- and (-)-pentazocine-induced potentiation at concentrations which did not affect contractions per se. These findings indicate that the exogenous application of ATP-induced twitch contraction in the mouse vas deferens is regulated by σ-receptors. In addition, the present ranking order suggests that the σ-receptor potentiating the ATP-induced twitch contraction at post-junctional sites may differ from the σ₁- and/or σ₂-receptor subtypes.     

西地那非对大鼠输精管的舒张作用及其机制

目的 观察西地那非（Sil）对体外大鼠输精管平滑肌的舒张效应及其机制.方法 ①取Wistar成年雄性大鼠16只,随机分为电刺激收缩组和高浓度氯化钾收缩组各8只,将大鼠颈椎脱臼处死,剖取输精管分成两段,其中一组分别以0.1～100.0 μmol•L^-1Sil直接作用于输精管;另一组给予L-NAME后再以0.1～100.0 μmol•L^-1Sil直接作用于输精管,采用台式平衡记录仪检测Sil对输精管平滑肌张力的影响;②将成熟雄性大鼠颈椎脱臼处死,剖取输精管分成两段,取附睾端输精管称重,用作cGMP测定;其他部分分为空白对照组、基础释放组、cGMP激发组（给予0.1 mmol•L^-1SNP激发）和L-NAME（0.1 mmol•L^-1）预孵育组,各组均给予3,10,100 μmol•L^-1Sil孵育.提取各组cGMP采用125I放射免疫法测定.结果 ①Sil使电刺激和高浓度氯化钾（80 mmol•L^-1）刺激体外大鼠输精管平滑肌收缩标本呈浓度依赖性舒张（均P＜0.05）,EC50分别为9.82和46.9 μmol•L^-1;②当L-NAME存在时,Sil对电刺激引起的收缩和高浓度氯化钾刺激引起的收缩的舒张量-效曲线右移,最大效应分别由（87.27±1.91）%降到（68.02±2.29）%（P＜0.05）,和（87.46±3.87）%降到（72.99±4.23）%（P＜0.05）, EC50分别增加到45.7和63.2 μmol•L-1（均P＜0.05）;③Sil可浓度依赖性升高cGMP含量（P＜0.05）,而且该作用能被L-NAME完全抑制;在硝普钠存在时,Sil能更进一步提高大鼠附睾端输精管平滑肌组织中的cGMP浓度（P＜0.05）.结论 Sil呈浓度依赖性舒张输精管,该作用可能与NO-cGMP途径和NO-cGMP非依赖性途径有关.     

Pre- and Postjunctional Effects of Diadenosine Polyphosphates in the Guinea-pig Vas Deferens

The pre- and postjunctional activities of a number of diadenosine polyphosphates were examined in the guinea-pig isolated vas deferens at the level of the membrane-potential, using a modified sucrose-gap technique. P¹,P³-Di(adenosine 5′)triphosphate (Ap₃A), P¹,P⁴-di(adenosine 5′)tetraphosphate (Ap₄A) and P¹,P⁵-di(adenosine 5′)pentaphosphate (Ap₅ A) all caused concentration-dependent depolarization of the smooth muscle membrane. The potency order was: Ap₅A > Ap₄A. Ap₃A. P¹, P²-Di(adenosine 5′)pyrophosphate (Ap₂A) did not evoke depolarization even at the highest concentration tested (1 mM). All the dinucleotides caused a reduction in the amplitude of evoked excitatory junction potentials (e.j.ps). The potency order was: Ap₅A = Ap₄A > Ap₃A > Ap₂A. The depolarizations evoked by the dinucleotides were markedly reduced by the selective P_2X-purinoceptor antagonist, pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS, 10 μM), as was the amplitude of the fully facilitated e.j.p. The inhibition of the e.j.p. evoked by Ap₃A and Ap₂A was reduced by the P₁-purinoceptor antagonist, 8-p-sulphophenyltheophylline (8-pSPT, 50 μM), but that evoked by Ap₅A and Ap₄A was not. Thus, Ap₃A, Ap₄A and Ap₅ A evoke depolarization of the guinea-pig vas deferens via P_2X-purinoceptors, and additionally Ap₂A and Ap₃A exert a prejunctional effect via P₁-purinoceptors. The prejunctional activity of Ap₄A and Ap₅A is mediated via an undefined purinoceptor, which is neither P₁ nor P_2X.     

Cholesterol-fed Rabbits: Study of the Response of the Vas Deferens to Adrenergic and Non-adrenergic Stimulus and to a K-Opioid Agonist

The aim of the present study was to analyse the contractility of the isolated vas deferens from hypercholesterolaemic rabbits; for this purpose we evaluated the contractile response induced by noradrenaline and by electrical stimulation. A significant increase in the amplitude of adrenergic and non-adrenergic responses was observed in vas deferens from hypercholesterolaemic rabbits. These data suggest an increase in the contractility of the smooth muscle in these animals.     

Interactions between Substance P and Norepinephrine in the Regulation of Nociception in Mouse Spinal Cord

Abstract: This study examined interactions between effects of the undecapeptide substance P and norepinephrine and the α-adrenoceptor agonist clonidine in the mouse spinal cord. All compounds were injected into the lumbar subarachnoid space, and effects on the tail-flick reflex and the behavioural response to intrathecal substance P were evaluated. The tail-flick response latencies were markedly increased 5–20 min. after intrathecal application of norepinephrine (0.0125–0.1 μg) or clonidine (0.0125–0.1 μg). The actions of both intrathecal norepinephrine (0.025 μg) and intrathecal clonidine (0.025 μg) were significantly attenuated when substance P (5 μg) was given intrathecally 55 and 45 min. before the agonists. There was a significant relationship between the tail-flick response latencies and the tail skin temperature. However, the tail-flick results were not due to changes in the skin temperature. Intrathecally applied substance P (10 ng) produced a response consisting of biting of the caudal part of the body and a few hindlimb scratches. The number of bites was significantly reduced 5 min. after injection of norepinephrine (0.1 μg) or clonidine (0.05–0.1 μg), but the number of scratches was unchanged. The data show that increased stimulation of spinal α-adrenoceptors inhibits a spinal nociceptive reflex as well as the action of substance P in the spinal cord. Substance P modulates the action of α-adrenoceptor agonists on the tail-flick reflex, which may tentatively be explained by downregulation of α-adrenoceptors by substance P.     

不同钙拮抗药对大鼠杏仁核电刺激点燃模型的作用比较

目的 比较不同类型钙拮抗药对大鼠杏仁核电刺激点燃癫模型的作用及其机制。方法 采用恒定电流刺激大鼠右侧杏仁核制备大鼠杏仁核电刺激点燃慢性癫模型，观察不同类型的钙拮抗药对大鼠杏仁核电刺激点燃动物模型的后放电时程（ADD）和Racine’s分级的影响，并进行给药前后的自身对照。结果 不同类型钙拮抗药对大鼠杏仁核电刺激点燃癫发作的作用不同。尼莫地平40～80 mg·kg^-1 灌胃可抑制大鼠杏仁核电刺激点燃癫发作，降低Racine’s 分级（均P＜0.01）；地尔硫200 mg·kg^-1灌胃可抑制ADD（P＜0.05）,但对Racine’s 分级无影响（P＞0.05）;乙琥胺100～250 mg·kg^-1 灌胃对大鼠杏仁核电刺激点燃癫发作及Racine’s 分级均无抑制作用（均P＞0.05）；苯妥英钠20 mg·kg^-1 皮下注射可抑制大鼠杏仁核电刺激点燃发作，降低Racine’s分级（均P＜0.01）;丙戊酸钠500 mg·kg^-1 灌胃可抑制大鼠杏仁核电刺激点燃发作，降低Racine’s 分级（均P＜0.05）;桂利嗪20～60 mg·kg^-1灌胃可抑制大鼠杏仁核电刺激点燃癫发作，降低Racine’s 分级（均P＜0.01）。 结论 L型和T型钙通道可能参与癫发病机制，L型钙拮抗药尼莫地平具有抗癫点燃作用；较大剂量地尔硫可抑制ADD，其机制可能与阻滞L型电压依赖性钙通道（VDCC）有关; T型钙拮抗药乙琥胺对杏仁核癫点燃无抑制作用，杏仁核癫点燃发作或癫大发作与丘脑神经元低阈值T型钙通道无关；苯妥英钠、丙戊酸钠可抑制杏仁核点燃癫发作;苯妥英钠作用的T型钙通道不同于乙琥胺，该两药也可能通过其他机制抗癫;丙戊酸钠可能兼有乙琥胺和苯妥英钠对钙通道的抑制作用;桂利嗪的抗癫作用可能与阻滞多种类型的电压依赖性钙通道有关。     

Analysis of Neurogenic Contractions Induced by ML-1035 and Other Benzamides in the Guinea-pig Non-stimulated Isolated Ileum

Abstract— 4-Amino-5-chloro-substituted benzamides have been shown to increase gastric motility in-vivo and enhance field-stimulated and peristaltic contractions in-vitro. The present experiments examined the contractile response to a series of benzamides in the guinea-pig non-stimulated ileum. Four benzamides elicited contractions in the isolated ileum which were expressed as a percentage of the contraction induced by 1 μm acetylcholine (% acetylcholine response = 12 ± 2, 19 ± 3, 26 ± 2, 51 ± 3, n= 13, 8, 17, and 21, with EC50 values of 0·85, 1·8, 5·7, and 14·2 μm for cisapride, zacopride, metocloprarmde, and ML-1035 (4-amino-5-chloro-2-((2-methylsulphinyl)-ethoxy)-N-(2-(diethylamino)-ethyl)-benzamide hydrochloride), respectively). ML-1035 contractions were completely blocked by atropine and tetrodotoxin, while ganglionic blockade with hexamethonium was ineffective. Metoclopramide has been reported to sensitize postjunctional muscarinic receptors, however, ML-1035 did not enhance acetylcholine-induced contractions. Tropisetron (ICS 205–930, 1 μm ), caused a parallel rightward shift in the concentration-response curve for both ML-1035 and zacopride (EC50 = 14·2 ± 1·3 and 1·8 ± 0·8 μm in the absence, and 26 ± 2·7 and 6·9 ± 2·3 μm in the presence of tropisetron for ML-1035 and zacopride, respectively) with apparent pK_B values of 5·9 and 6·0 for the respective compounds. 5-Hydroxytryptaminergic receptor desensitization by 2-methyl-5-hydroxytryptamine (5-HT₃) and 5-methoxytryptamine (5-HT₄), attenuated the response to ML-1035. We also examined the effect of the benzamides on [³H]acetylcholine release from longitudinal muscle myenteric plexus preparations; however, these compounds had little effect on basal [³H]acetylcholine release. Thus, the pharmacological data indicate that the benzamides can elicit neurogenic contractions in the non-stimulated ileum by activating postganglionic, cholinergic neurons which is independent of an effect on smooth muscle.     

P2X and P2Y Receptors Mediate Contraction Induced by Electrical Field Stimulation in Feline Esophageal Smooth Muscle

It is well-known that electrical field stimulation (EFS)-induced contraction is mediated by a cholinergic mechanism and other neurotransmitters. NO, ATP, calcitonin gene-related peptide (CGRP), and substance P are released by EFS. To investigate the purinergic mechanism involved in the EFS-induced contraction, purinegic receptors antagonists were used. Suramine, a non-selective P2 receptor antagonist, reduced the contraction induced by EFS. NF023 (10^-7~10^-4 M), a selective P2X antagonist, inhibited the contraction evoked by EFS. Reactive blue (10^-6~10^-4 M), selective P2Y antagonist, also blocked the contraction in a dose-dependent manner. In addition, P2X agonist α,β-methylene 5''-adenosine triphosphate (αβMeATP, 10^-7~10^-5 M) potentiated EFS-induced contraction in a dose-dependent manner. P2Y agonist adenosine 5''-[β-thio]diphosphate trilithium salt (ADPβS, 10^-7~10^-5 M) also potentiated EFS-induced contractions in a dose-dependent manner. Ecto-ATPase activator apyrase (5 and 10 U/ml) reduced EFS-induced contractions. Inversely, 6-N,N-diethyl-D-β,γ-dibromomethylene 5''-triphosphate triammonium (ARL 67156, 10^-4 M) increased EFS-induced contraction. These data suggest that endogenous ATP plays a role in EFS-induced contractions which are mediated through both P2X-receptors and P2Y-receptors stimulation in cat esophageal smooth muscle.     

The Morphological and Molecular Changes of Brain Cells Exposed to Direct Current Electric Field Stimulation

Background:

The application of low-intensity direct current electric fields has been experimentally used in the clinic to treat a number of brain disorders, predominantly using transcranial direct current stimulation approaches. However, the cellular and molecular changes induced by such treatment remain largely unknown.

Methods:

Here, we tested various intensities of direct current electric fields (0, 25, 50, and 100V/m) in a well-controlled in vitro environment in order to investigate the responses of neurons, microglia, and astrocytes to this type of stimulation. This included morphological assessments of the cells, viability, as well as shape and fiber outgrowth relative to the orientation of the direct current electric field. We also undertook enzyme-linked immunosorbent assays and western immunoblotting to identify which molecular pathways were affected by direct current electric fields.

Results:

In response to direct current electric field, neurons developed an elongated cell body shape with neurite outgrowth that was associated with a significant increase in growth associated protein-43. Fetal midbrain dopaminergic explants grown in a collagen gel matrix also showed a reorientation of their neurites towards the cathode. BV2 microglial cells adopted distinct morphological changes with an increase in cyclooxygenase-2 expression, but these were dependent on whether they had already been activated with lipopolysaccharide. Finally, astrocytes displayed elongated cell bodies with cellular filopodia that were oriented perpendicularly to the direct current electric field.

Conclusion:

We show that cells of the central nervous system can respond to direct current electric fields both in terms of their morphological shape and molecular expression of certain proteins, and this in turn can help us to begin understand the mechanisms underlying the clinical benefits of direct current electric field.     

The Metabolism of Sympathomimetic Bronchodilator Drugs by the Isolated Perfused Dog Lung

Abstract

1. The metabolism of three bronchodilator drugs, isoprenaline, isoetharine and terbutaline, was studied in the isolated perfused dog lung.

2. Isoprenaline and isoetharine, administered into the vascular system or the bronchial tree, were extensively O-methylated and this pattern of metabolism was reflected in the drug accumulated in lung tissue.

3. Approximately 30% of isoprenaline absorbed from the airways was converted to 3-O-methylisoprenaline in its first pass through the lung.

4. Terbutaline, which is not a catecholamine, was not significantly metabolized by the lung.

5. None of these drugs or their O-methyl metabolites was conjugated in significant amounts by the lungs, nor were acidic metabolites, from attack by monoamine oxidase, observed.     

Potentiation by α-Methyltyrosine of the Suppression of Food-Reinforced Lever-Pressing Behaviour Induced by Antipsychotic Drugs

Abstract The mode of action whereby α-methyltyrosine (α-MT) potentiates the behavioural effects induced by catecholamine receptor blocking antipsychotic drugs was investigated in rats trained to lever-press for food on a fixed-ratio 40 schedule of reinforcement. It was found that α-MT (20 mg/kg intraperitoneally - 4 hrs potentiates the effects induced by pimozide (0.04 mg/kg intra-peritoneally - 6 hrs) which preferentially blocks central dopamine (DA) receptors, but not the effects induced by phenoxybenzamine (0.5 mg/kg intra-peritoneally - 30 min.) which blocks central noradrenaline (NA) receptors. Furthermore, the behavioural suppression induced by chlorpromazine (0.5 mg/kg intraperitoneally - 15 min.), thioridazine (1.5 mg/kg intraperitoneally - 15 min.), or haloperidol (0.02 mg/kg intraperitoneally - 15 min.) were not potentiated by the administration of the inhibitor of DA-β-hydroxylase, bis-(4-methyl-1-homo-piperazinylthiocarbonyl) disulfide (FLA-63) (4 mg/kg subcutaneously - 1 hr). The potentiation by α-MT of the clinical effects of antipsychotic drugs and of their behavioural effects in animal experiments is in all probability due to a blockade by α-MT of a feed-back mediated compensatory increase in the catecholamine synthesis as a result of a blockade of central NA and/or DA receptors by the antipsychotic drugs. Since, in the present experiments, the behavioural effects induced by drugs which block central DA but not NA receptors were potentiated by the simultaneous administration of α-MT, it seemed probable that the disruption of conditioned behaviours by antipsychotic drugs is due to a blockade of central DA receptors. In view of the fact that the ability to selectively disrupt conditioned behaviours is shared by a wide range of antipsychotic drugs differing in chemical structure and also in their mode of action, it is possible that a blockade of DA neurotransmission is also of primary importance for the clinical effects induced by antipsychotic drugs.     

Involvement of NK1 and NK2 Receptors in Pulmonary Responses Elicited by Non-adrenergic,Non-cholinergic Vagal Stimulation in Guinea-pigs

Previous studies from our laboratory using exogenously administered neurokinin (NK) agonists have shown that both NK₁- and NK₂-receptor subtypes are involved in plasma extravasation in the guinea-pig airways. In the present study, we have extended these observations using antidromic vagal stimulation to stimulate sensory c-fibres as a means of eliciting the release of endogenous tachykinins in propranolol- and atropine-treated guinea-pigs. Antidromic vagal stimulation (5 ms, 30 s) induced frequency-dependent (1–10 Hz) bronchoconstriction that was completely abolished by co-administration of the NK₁-selective antagonist CP-99,994 ((2s-methoxy-benzyl)-(2-phenyl-piperidin-3s-yl)-amine), and the NK₂-selective antagonist SR-48,968 ((S)-N-methyl-N-[4-(4-acetylamino-4-phenyl piperidino)-2-(3,4-dichlorophenyl) butyl]benzamide), each at a dose sufficient to block NK₁ and NK₂ receptors, respectively (each at 0.3 mg kg^?1, i.v.). In contrast, SR-48,968 when given alone only partially blocked the vagal stimulation-induced bronchospasm, whereas CP-99,994 had no effect. Significant increases (2–3-fold) in plasma extravasation of [¹²⁵I]fibrinogen in the trachea, main bronchi, distal airways and oesophagus following vagal stimulation (5 Hz, 5 min, 10 V, 5 ms) were observed. Pretreatment with the neutral endopeptidase inhibitor, thiorphan (1 mg kg^?1, i.v.), and the angiotensin-converting enzyme inhibitor, enalapril (1 mg kg^?1, i.v.), potentiated both vagal stimulation-induced bronchoconstriction and plasma leakage in all tissues examined. This potentiation was due to reduced metabolism of endogenously released tachykinins since enhanced plasma overflow of immuno-reactive substance P was observed following vagal stimulation in thiorphan- and enalapril-treated guinea-pigs. CP-99,994 substantially blocked plasma leakage in all parts of the airways and in the oesophagus. In comparison, SR-48,968 had no significant effect in the trachea and the oesophagus but partially inhibited plasma leakage in the main bronchi and distal airways. Co-administration of both CP-99,994 and SR-48,968 abolished the residual plasma leakage in these two regions. These results support the hypothesis that both NK₁ and NK₂ receptors are involved in tachykinin-induced pulmonary responses in the airways.     

替代对照品法在镇静安神类药物HPLC快速检验方法中的应用

目的 采用替代对照品法建立镇静安神类药物氯氮卓、马来酸咪达唑仑、硝西泮、艾司唑仑、奥沙西泮、劳拉西泮和阿普唑仑的高效液相色谱快速检验方法。方法 采用Agilent ZORBAX Eclipse Plus C₈色谱柱(4.6 mm×150 mm,5 μm),流动相：0.01 mol·L^-1磷酸二氢钾溶液(pH 2.5)-(甲醇-乙腈1∶1)(57∶43),流速：1.0 mL·min^-1,柱温：30 ℃。采用相对容量因子和紫外光谱相似度双指标进行定性;采用相对校正因子法进行定量分析。结果 在确定的色谱条件下,氯氮?、咪达唑仑、硝西泮、艾司唑仑、奥沙西泮、劳拉西泮和阿普唑仑完全分离;采用紫外光谱相似度和相对容量因子进行定性,结果准确可靠;采用替代对照品法,计算药物的相对校正因子进行含量测定,能有效减少对照品的使用,加快高效液相色谱分析速度。结论 该方法快速、简便、可靠,适用于快速检验镇静安神类药物。     

Effects of Different Agents on the Contractile Response Elicited by Extracellular Calcium after Depletion of Internal Calcium Stores in Rat Isolated Aorta

Abstract— Noradrenaline, 1 μm, induced a sustained contractile response in rat isolated aorta in the presence and in the absence of extracellular Ca²⁺. After depleting the noradrenaline-sensitive intracellular Ca²⁺ stores, an increase in the basal tone of the aorta was observed during the incubation period in the presence of Ca²⁺ and in the absence of the agonist. We have tested the possible pathways through which Ca²⁺ enters the cell to refill the previously depleted Ca²⁺ pools, a process that is accompanied by an increase in tension. The magnitude of this increase does not depend on the presence of Mg²⁺ in the extracellular medium nor on the temperature, suggesting that it is mediated by an event that does not depend on intracellular energy or Ca²⁺, Mg²⁺-ATPase. It is inhibited in a concentration-dependent manner by an unspecific relaxing compound, caffeine, and an organic Ca²⁺ entry blocker, verapamil, but not by an inorganic Ca²⁺ entry blocker, lanthanum. Caffeine (10 Mm) and verapamil (10^?5 m) completely inhibited the increase in the resting tone, but only verapamil abolished the refilling of the noradrenaline-sensitive Ca²⁺ pools, indicating that the extracellular Ca²⁺ enters the cell through voltage-operated Ca²⁺ channels. Caffeine inhibited the increase in the resting tone without blocking the refilling process of the stores at 37°C, but at 25°C a partial inhibition of the repletion of internal Ca²⁺ pools was observed. These results confirm previous work that showed a temperature-dependent activity of caffeine.