Vascular mechanisms of monodesmosidic triterpene saponins isolated from Passiflora quadrangularis L / Mecanismos vasculares de saponinas triterpénicas monodesmosídicas aisladas de Passiflora quadrangularis L

Background: Passiflora quadrangularis L. has antihypertensive and anxiolytic properties observed in experimental models. Objectives: The aim of this work was to establish the vascular effects exerted by two known monodesmosidic triterpene saponins, 3-O-ß-D-glucopyranosyloleanolic acid (Compound 1) (not previously described for this plant) and, 3-O-[ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosyl] oleanolic acid (Compound 2), isolated from the ethanolic extract of Passiflora quadrangularis L. leaves. Methods: The structural elucidation was achieved by Nuclear Magnetic Resonance (NMR) experiments and High-Resolution Mass Spectrometry (HRMS). Aortic rings from Wistar rats, previously stimulated with phenylephrine (PE, 1µM) and washed, were exposed to cumulatively concentrations of compound 1 and compound 2 (10 to 400 µM). Ethanolic extract from leaves of P. quadrangularis L. (10 to 320 µg/ mL) and clonidine (1nM to 100µM) were also used for comparison. Concentration response curves of compounds 1 and 2 were examined in presence and absence of: endothelium, the alpha-2 antagonist yohimbine (1 and 100 µM), the alpha non selective antagonist phentolamine (1µM), the alpha-1 antagonist prazosin (1µM) and the calcium channel blocker verapamil (10 and 100 µM). In addition, cumulatively response curve of acetylcholine (ACh, 10nM to 10µM) and sodium nitroprusside (SNP, 1nM to 100µM) were assayed in rings precontracted with compounds 1 and 2 (400 µM). Results: Compounds 1 and 2 elicited a vasoconstriction response in intact aorta rings in similar way (pEC50: 3.92±0.01 and 4.09±0.01, respectively), effect that did not change in denuded rings (pEC50: 3.90±0.01 and 4.11±0.01). The potency order (pEC50) of compounds 1 and 2 decreased according to the following: verapamil (3.53±0.01 and 3.90±0.02; p<0.05) < yohimbine (3.65±0.01 and 3.94±0.02; p<0.05) < prazosin (3.86±0.01 and 4.30±0.02) < phentolamine (4.05±0.02 and 4.05±0.01). SNP but not ACh, was able to decrease the vasopressor effect of compounds 1 and 2 (pIC50: 8.61±0.01 and 8.24 ± 0.15, respectively). Conclusions: Compounds 1 and 2 are key metabolites responsible for the ex vivo vasoconstrictor response induced by P. quadrangularis L. Activation of voltage-dependent calcium channels and/or α2-adrenergic receptors stimulation could be mechanisms implicated.

Antecedentes: Passiflora quadrangularis L. tiene propiedades antihipertensivas y ansiolíticas observadas en modelos animales. Objetivos: El objetivo de este trabajo fue establecer los efectos vasculares ejercidos por dos conocidas saponinas triterpénicas monodesmosídicas: el ácido 3-O-ß-D glucopiranosiloleanólico (Compuesto 1) (no descrito previamente para esta especie vegetal) y el ácido 3-O-[ß-D-glucopiranosil- (1→2)-ß-D-glucopiranosil]oleanólico (Compuesto 2), aisladas del extracto etanólico de las hojas de Passiflora quadrangularis L. Métodos: La elucidación estructural se llevó a cabo mediante experimentos de Resonancia Magnética Nuclear (NMR) y determinaciones de Espectrometría de Masas de Alta Resolución (HRMS). Los anillos aórticos de ratas Wistar, previamente estimulados con fenilefrina (PE, 1 µM) y lavados, fueron expuestos a concentraciones acumulativas del compuesto 1 y compuesto 2 (10 a 400 µM). El extracto etanólico de las hojas de P. quadrangularis L. (10 a 320 µg / ml) y clonidina (1 nM a 100 µM) se utilizaron para la comparación. Las curvas de concentración respuesta de los compuestos 1 y 2 se examinaron en presencia y ausencia de: endotelio, el antagonista alfa-2 yohimbina (1 y 100 µM), el antagonista alfa no selectivo fentolamina (1 µM), el antagonista alfa-1 prazosina (1 µM) y el bloqueador de canales de calcio verapamilo (10 y 100 µM). Además, la curva de concentraciones acumulativas de acetilcolina (ACh, 10 nM a 10 µM) y nitroprusiato de sodio (SNP, 1 nM a 100 µM) se ensayó en anillos pre-contraídos con los compuestos 1 y 2 (400 µM). Resultados: Los compuestos 1 y 2 provocaron una respuesta de vasoconstricción en los anillos de aorta intactos de manera similar (pEC50: 3.92 ± 0.01 y 4.09 ± 0.01, respectivamente), este efecto no cambió en los anillos denudados (pEC50: 3.90 ± 0.01 y 4.11 ± 0.01). El orden de potencia (pEC50) de los compuestos 1 y 2 disminuyó de la siguiente manera: verapamilo (3.53 ± 0.01 y 3.90 ± 0.02; p <0.05) < yohimbina (3.65 ± 0.01 y 3.94 ± 0.02; p <0.05) < prazosina (3.86 ± 0.01 y 4.30 ± 0.02)

Mechanisms underlying the vascular relaxation activities of Zingiber officinale var. rubrum in thoracic aorta of spontaneously hypertensive rats / 中西医结合学报

OBJECTIVE@#To evaluate vasorelaxant and vasoconstriction effects of Zingiber officinale var. rubrum (ZOVR) on live rats and isolated aortic rings of spontaneously hypertensive rats (SHRs).@*METHODS@#Extracts of ZOVR were subjected to in-vivo antihypertensive screening using noninvasive blood pressures in SHRs. The most potent extract, ZOVR petroleum ether extract (ZOP) was then fractionated using n-hexane, chloroform and water. Isolated thoracic aortic rings were harvested and subjected to vascular relaxation studies of n-hexane fraction of ZOP (HFZOP) with incubation of different antagonists such as N-nitro-l-arginine methyl ester (L-NAME, 10 µmol/L), indomethacin (10 µmol/L), methylene blue (10 µmol/L), atropine (1 µmol/L), glibenclamide (10 µmol/L), prazosin (0.01 µmol/L), and propranolol (1 µmol/L).@*RESULTS@#During the screening of various ZOVR extracts, ZOP produced the most reduction in blood pressures of SHRs and so did HFZOP. HFZOP significantly decreased phenylephrine-induced contraction and enhanced acetylcholine-induced relaxation. L-NAME, indomethacin, methylene blue, atropine, and glibenclamide significantly potentiated the vasorelaxant effects of HFZOP. Propranolol and prazosin did not alter the vasorelaxant effects of HFZOP. HFZOP significantly suppressed the Ca-dependent contraction and influenced the ratio of the responses to phenylephrine in Ca-free medium.@*CONCLUSION@#This study demonstrates that ZOP may exert an antihypertensive effect in the SHR model. Its possible vascular relaxation mechanisms involve nitric oxide and prostacyclin release, activation of cGMP-K channels, stimulation of muscarinic receptors, and transmembrane calcium channel or Ca release from intracellular stores. Possible active compounds that contribute to the vasorelaxant effects are 6-gingerol, 8-gingerol and 6-shogaol.

Study on Vasodilatory Effect of Oxysophocarpine on Isolated Thoracic Aortic Rings of Rats and Its Mechanism / 中国药房

OBJECTIVE： To study the vasodilatory effect of oxysophocarpine （OSC） on isolated thoracic aortic rings of rats and its possible mechanism. METHODS： Thoracic aortic rings of rats were collected （called “vascular ring” for short）. Using K-H nutrient solution as blank control and the diastolic rate as index， the effects of different concentrations （0.2-1.0 mg/mL） of OSC on normal vascular rings in basal state， normal or endothelium-free vascular rings pre-contracted by norepinephrine （PE， 1×10－6 mol/L） were investigated. After pre-culturing normal thoracic aortic rings by nitric oxide synthase inhibitor L-nitro-arginine methyl ester（L-NAME）and cyclooxygenase inhibitor indomethacin（INDO），as well as pre-culturing endothelium-free vascular rings by potassium ion channel blocker BaCl2，tetraethylammonium（TEA）and 4-aminopyridine（4-AP）， the diastolic effects of OSC of different concentrations （0.2-1.0 mg/mL） on the above vascular rings were investigated by using the same method. RESULTS： Compared with blank control， there was no significant effects of different concentrations of OSC on the diastolic rate of normal vascular rings in basal state （P＞0.05）， but 0.4-1.0 mg/mL OSC could significantly improve the diastolic rate of normal or endothelium-free vascular rings pre-contracted by PE （P＜0.01）， in concentration-dependent manner. After preculturing with L-NAME， INDO， 4-AP and BaCl2， different concentrations of OSC had no significant effect on the diastolic rate of normal or endothelium-free vascular rings pre-contracted by PE （P＞0.05）. After pre-culturing with TEA and Gli， 0.4-1.0 mg/mL OSC could significantly reduce the diastolic rate of endothelium-free vas- cular rings pre-contracted by PE （P＜0.01）. CONCLUSIONS： OSC did not significantly dilate the thoracic aortic rings of rats in the basal state within the dose range （0.2-1.0 mg/mL）， but OSC of 0.4-1.0 mg/mL have significant diastolic effects on the normal or endothelium-free thoracic aortic rings of rats pre-contracted with PE. The mechanism of thoracic aortic rings dilation is endothelium-independent， which may be associated with receptor operational calcium channel，Ca2+-activated potassium channels and ATP-sensitive potassium channels.

The protective effects of Astragaloside Ⅳ on diastolic function of rat thoracic aortic rings impaired by microvesicles / 中国应用生理学杂志

OBJECTIVES@#To investigate the effects of Astragaloside IV (AST) on diastolic function of rat thoracic aorta rings which was injured by microvesicles derived from hypoxia/reoxygenation (H/R)-treated human umbilical vein endothelial cells (HUVECs), and the mechanism of AST.@*METHODS@#H/R-induced endothelial microvesicles (H/R-EMVs) were generated from cultured HUVECs under the condition of hypoxia for 12 hour/Reoxygenation for 4 hour, H/R-EMVs were stored in D-Hank's solution. Male Wistar rats were underwent thoracotomy, the thoracic aorta with intact endothelium were carefully removed and cut into 3~4 mm rings. The experiment was divided into six groups. H/R-EMVs group:thoracic aortic rings of rats were incubated in culture medium and treated with H/R-EMVs in a final concentration of 10g/ml; different doses of AST groups:thoracic aortic rings of rats were treated with 10, 20, 40, 60 mg/L AST co-incubated with 10g/ml H/R-EMVs respectively; control group were treated with the same volume of D-Hank's solution. Duration of incubation was 4 h, each group was tested in five replicate aortic rings. Effects of AST on endothelium-dependent relaxation were detected. The production of nitric oxide (NO) and the level of endothelial NO synthase (eNOS), phosphorylated eNOS (p-eNOS, Ser-1177), serine/threonine kinase (Akt), phosphorylated Akt (p-Akt, Ser-473), extracellular regulated protein kinases (ERK1/2) and phosphorylated ERK1/2 (p-ERK1/2, Thr202/Tyr204) of rat thoracic aortic rings were detected.@*RESULTS@#Teng/ml H/R-EMVs could impaire the relaxation of rat thoracic aortic rings significantly (<0.01). Compared with H/R-EMVs group, relaxation of rat thoracic aortic rings was increased by 20, 40 and 60 mg/L AST in a concentration-dependent manner (<0.01), the level of NO production was also enhanced (<0.05, <0.01). The level of t-eNOS, t-Akt and ERK1/2 was not changed, but the level of p-eNOS, p-Akt and p-ERK1/2 increased by the treatment with AST (<0.01).@*CONCLUSIONS@#AST could effectively ameliorate endotheliumdependent relaxation of rat thoracic aortic rings impaired by H/R-EMVs in a concentration-dependent manner, the mechanism might involve the increase in production of NO, and the protein level of p-eNOS, p-Akt and p-ERK1/2.

Chronic intermittent hypobaric hypoxia enhances vasodilative effects of paeonol on isolated thoracic aorta rings of rats / 中国药理学通报

Aim To investigate the effect of chronic intermittent hypobaric hypoxia ( CIHH) on the paeonol induced vasomotion of isolated rat ’ s thoracic aorta rings and its underlying mechanisms. Methods Spra-gue-Dawlay ( SD ) rats were randomly divided into 2 groups: control group ( CON ) and CIHH treatment group ( CIHH) . CIHH rats were exposed to hypoxia in a hypobaric chamber simulating 5 000 m altitude, 6 hours daily for 28 days. CON rats lived in the same en-vironment as CIHH animals except hypoxia. Organ bath technique was used to observe the effect of pae-onol on isolated thoracic aorta rings of rats. Results There were no significant differences of noradrenaline ( NE )- and KCl-induced contraction in thoracic aorta rings among CIHH and CON rats;CIHH enhanced va-sodilative effects of paeonol on isolated thoracic aorta rings of rats; the vasodilative effects on CIHH rats could be partly decreased by β-receptor blocker prop-ranolol,ATP-sensitive potassium channel ( KATP ) bloc-ker glibenclamide and NO synthase inhibitor L-NAME. Paeonol significantly inhibited NE-induced intracellular and extracellular calcium-dependent contraction in CIHH rats. Paeonol didn ’ t inhibit NE-induced con-traction by intracellular calcium release and its inhibi-tory effect couldn ’ t be blocked by glibenclamide in CON. Vasodilative effects of paeonol couldn ’ t be re-versed by indomethacin, a cyclooxygenase inhibitor, in CIHH and CON rats. Conclusion CIHH significantly enhances vasodilative effects of paeonol on isolated tho-racic aorta rings of rats. Besides promoting the signa-ling pathway of paeonol in CON, CIHH significantly enhances vasodilative effects of paeonol via activating KATP and inhibiting Ca2+ release from sarcoplasmic re-ticulum.

Effect of cGMP-dependent protein kinase G inhibitor (D)-DT-2 on the lipopolysaccharide-induced hyporesponsiveness of rat vascular ring / 中华麻醉学杂志

Objective To investigate the effect of specific cGMP-dependent protein kinase G (PKG) inhibitor (D)-DT-2 on the contractile function of rat vascular rings after being exposed to lipopolysaccharide (LPS).Methods The experiment was performed in 2 parts.Part Ⅰ:The Sprague-Dawley rat thoracic aortic rings were randomly divided into 3 groups (n =5 each):KH group,DT-2 group and (D)-DT-2 group.KH,DT-2 and (D)-DT-2 were added to the aortic ring after being dilated with 8-Br-cGMP 50 μmol/L for 25 min and the changes in tension of vascular rings were measured.Part Ⅱ:The rat thoracic aortic rings were randomly divided into 4 groups (n =5 each):control group,LPS group,LPS-DT2 group and LPS-(D)-DT2 group.After being incubated with LPS for 3 h in vitro.The Emax and EC50 were compared among the 4 groups.Results Part Ⅰ:Both DT-2 and (D)-DT-2 could contract the vascular rings dilated with 8-Br-cGMP and the Emax was significantly higher in (D)-DT-2 group than DT-2 group (P ＜0.05).Part Ⅱ]:Both DT-2 and (D)-DT-2 significantly improved the contractile function of vascular ring after being exposed to LPS.Emax was significantly higher,while EC50 was lower in groups DT-2 and (D)-DT-2 than in LPS group (P ＜0.01).Emax was significantly increased,while EC50 was decreased in LPS-(D)-DT-2 group as compared with LPS-DT-2 group (P ＜ 0.05).Conclusion PKG inhibitor can improve the contractile function of the vascular rings incubated with LPS and the efficacy of (D)-DT-2 is better than DT-2 in recovering the vascular reactivity.

Amygdalin inhibits angiogenesis in the cultured endothelial cells of diabetic rats.

Background: Angiogenesis contributes to different physiological and pathological conditions. The aim of this study was to investigate for the first time the antiangiogenic effects of amygdalin on the cultured endothelial cells of diabetic rats. Materials and Methods: A total of 20 streptozotocin-induced diabetic rats were divided into two equal groups of control and amygdalin-treated animals. Eight weeks after the induction of diabetes, amygdalin was injected intraperitoneally (3 mg/kg) to the rats of the treatment group. One day later, rats were sacrificed; the aortic arteries were excised and cut as 2 mm rings. Each aortic ring was incubated in a cell-culture well for 7 days. The process of angiogenesis was monitored by counting the number of microvessels and primary microtubules in each well. Results: Optic microscopy showed proliferation and migration of new endothelial cells to the fibrin gels. The endothelial cells produced primary microtubules which gradually made several branches and finally made a vascular matrix. The number of the primary microtubules and microvessels were significantly lower in the amygdalin-treated vs. control group (P < 0.01). Conclusion: Therefore, amygdalin exerts inhibitory effects on angiogenesis in aortic rings of diabetic rats and may pave a new way for treatment of unfavorable angiogenic conditions.

Isolated aorta model and its contribution to phytopharmacology / Modelo de aorta aislada y su contribución a la fitofarmacología

Since the early 50's until now the isolated thoracic aorta has been a traditional and productive model for pharmacological studies. This experimental model has been closely related to Doctor Robert Furchgott's research. The discovery of the role of endothelium in the vasorelaxation induced by acetylcholine (ACh), represented a milestone in biological sciences and also had an important consequence on the isolated aorta preparation. In this work, we describe the isolated aorta technique and the improvements made in Doctor Penna's laboratory at Facultad de Medicina, Universidad de Chile, as well as the Mexican contribution. Since endothelium plays a key role on vascular relaxation and its dysfunction is one of first indicators (biomarker) of cardiovascular diseases, the isolated aorta model is a valuable preparation. Considering the great amount of phytochemical present in many natural sources, like vegetables, fruits and medinal plants, we expect this model to continue delivering significant contributions to the knowledge in pharmacology and phytopharmacology.

Desde principios de los años 50 hasta ahora la aorta torácica aislada ha sido un modelo tradicional y productivo para estudios farmacológicos. Este modelo experimental ha estado estrechamente relacionado con la investigación realizada por el Doctor Robert Furchgott. El descubrimiento de la función del endotelio en la vasodilatación inducida por la acetilcolina (ACh), representó un hito en las ciencias biológicas y también tuvo una consecuencia importante en la preparación de aorta aislada. En este trabajo se describe la técnica de aorta aislada y las mejoras realizadas en el laboratorio del Doctor Penna en la Facultad de Medicina, Universidad de Chile, así como la contribución de investigadores mexicanos. Puesto que el endotelio juega un papel clave en la relajación vascular y su disfunción es uno de los primeros indicadores (biomarcadores) de enfermedad cardiovascular, el modelo de aorta aislada es una valiosa preparación. Teniendo en cuenta la gran cantidad de fitoquímicos presentes en muchas fuentes naturales como verduras, frutas y plantas medicinales, podemos esperar que este modelo continúe entregando importantes aportes al conocimiento en farmacología y fitofarmacología.

Influence of anisodamine on in vitro vascular relaxation function in normal and spontaneous hypertension rats / 第二军医大学学报

Objective: To observe the influence of anisodamine on relaxation function of isolated Wistar and spontaneously hypertensive rat (SHR) aortic rings, and to investigate the underlying mechanism. Methods: The SHR aorta rings were irrigated with anisodamine and the effect of anisodamine on relaxation of isolated aortic rings was observed in normal and spontaneous hypertension rats before and after pretreatment with phenylephrine (PE) or L-nitroarginine methylester (L-NAME). Results: The accumulated concentration of anisodamine showed significantly different relaxing effects on PE-precontracted aortic ring with or without endothelium (P0.05). Pretreatment with non selective NOS inhibitor L-NAME significantly inhibited the relaxing effect of anisodamine on the aortic ring with endothelium (P<0.05). L-NAME partially blocked the relaxing effect of anisodamine on SHR rats, with the maximal relaxation being 61% and 11.9% (P<0.01) before and after blocking, respectively. Conclusion: Anisodamine can enlarge isolated aorta of rats through endothelial and smooth muscle.

Influence of anisodamine chronic administration on the vascular function and morphology spontaneously hypertensive rats / 国际外科学杂志

Objective To investigate the influence of Anisodamine chronic administration on the vascular function and morphology of SHR. Methods The SHR were injected by chronic abdominal Anisodamine; Then the SHR were sacrificed after ten weeks. The abdominal aorta were obtained after perfusion and the changes of aorta morphology were observed under a microscope. The influence of Anisedamine on the vasculovr funtion was investigated by the rat's aorta rings perfusion. Results In the physiological state, given SHR long-term Anisodamine, the vascular endothelial and smooth muscle relaxation will significantly improve; Anisodamine chronic adminstration can inhibit the formation of aortic aneurysm and change a benign vascular structure. Conclusion Anisodamine chronic adminstration will improve the vascular endothelial and smooth muscle relaxation, and change a benign vascular structure, Anisodamine has a protective effect on endothelial and smooth muscle.

Cardiovascular effects induced by the hydroalcoholic extract of the stem of Xylopia cayennensis in rats / Efeitos cardiovasculares induzidos pelo extrato hidroalcoólico das cascas de Xylopia cayennensis em ratos

The cardiovascular effects induced by the hydroalcoholic extract of the stem of Xylopia cayennensis (HEXC) were studied in rats using a combined in vivo and in vitro approach. In non-anesthetized rats, HEXC injections produced a significant and dose-dependent hypotension associated with an increase in heart rate. The hypotensive response was not attenuated after nitric oxide (NO) synthase blockade, L-NAME (20 mg/Kg, i.v.). In isolated rat superior aortic rings, HEXC was able to relax the tonus induced by phenylephrine (1 µM) and KCl (80 mM), (EC50 = 85±13 and 62±5 µg/mL, respectively). The smooth muscle-relaxant activity of HEXC was not inhibited by removal of vascular endothelium (EC50 = 58±6 µg/mL). HEXC antagonized CaCl2-induced contractions in depolarizing medium nominally without Ca2+. HEXC inhibited the intracellular calcium-dependent transient contractions induced by caffeine (20 mM) in Ca2+-free solution, but not those induced by norepinephrine (1 µM). In isolated rat atrial preparations, HEXC produced negative inotropic and chronotropic responses (IC50= 534±42 and 259±22 µg/mL, respectively). The results obtained suggest that the hypotensive effect of HEXC is probably due to a peripheral vasodilatation, at least, secondary to an interference with the Ca2+ mobilization as a consequence of voltage-dependent Ca2+ channel blockade and the inhibition of Ca2+ release from caffeine-sensitive intracellular stores. Finally, HEXC acts directly on the heart decreasing contractility and heart rate, these effects are of little importance to the expression of the hypotensive response induced by HEXC.

Os efeitos cardiovasculares induzidos pelo extrato hidroalcoólico do caule de Xylopia cayennensis (EHXC) foram estudados em ratos, utilizando uma abordagem combinada in vivo e in vitro. Em ratos não anestesiados, EHXC induziu uma hipotensão não dependente de dose associada com um aumento da freqüência cardíaca. Esta resposta hipontesora não foi atenuada depois do bloqueio com L-NAME (20 mg/Kg, i.v.). Em anéis de aorta isolados de rato, EHXC foi capaz de relaxar o tônus induzido por fenilefrina (1 µM) e KCl (80 mM), (CE50 = 85±13 e 62±5 µg/mL, respectivamente). A atividade vasorelaxante do HEXC não foi inibida pela remoção do endotélio vascular (CE50 = 58±6 µg/mL). HEXC antagonizou as contrações induzidas por CaCl2 em meio despolarizante nominalmente sem Ca+2. EHXC antagonizou de maneira dependente de concentração as contrações transientes induzidas por cafeína (20 mM), em meio livre de Ca2+, contudo não alterou aquelas induzidas por noradrenalina (1 µM). Em átrio isolado de rato, EHXC induziu um efeito inotrópico e cronotrópico negativo (CI50= 534±42 µg/mL e 259±22 µg/mL; respectivamente). Os resultados obtidos demonstram que EHXC apresenta um potente efeito hipotensor, provavelmente conseqüência da diminuição da resistência periférica total que parece ser, em parte, devido a uma ação inibitória sobre o influxo de Ca+2 através de canais de cálcio dependentes de voltagem e também através da inibição da liberação de Ca+2 dos estoques intracelulares sensíveis à cafeína. HEXC atua diretamente no coração diminuindo a contratilidade e a freqüência cardíaca, estes efeitos têm importância pequena na expressão da resposta hipotensiva induzida por HEXC.

Effects of Rocuronium on Smooth Muscle Tension of Isolated Rat Thoracic Aorta / 대한마취과학회지

BACKGROUND: The cardiovascular effects of muscle relaxants may be produced by a muscarinic receptor block, ganglion block, increased noradrenaline release and blockage of it's reuptake or histamine liberation. However certain analogues of steroidal muscle relaxants directly cause relaxation of isolated vascular smooth muscles. Rocuronium is the 2-morpholino, 3-desacetyl, 16-N-allyl-pyrrolidino derivative of vecuronium, known to have a relative lack of ganglion blocking, sympathomimetic effects or histamine release. The aim of this study was to investigate the effect and action mechanism of rocuronium on isolated aortic smooth muscle in rats. METHODS: The ability of rocuronium to elicit a direct relaxant effect on vascular smooth muscle has been studied using isolated rat thoracic aortic rings contracted with phenylephrine (PE). Each ring of aortic arteries was suspended on wire supports in a 20 ml tissue bath under 2 g of resting tension. All tissues were bathed in Tris Tyrode solution at 37degrees C and 100% oxygen was supplied. RESULTS: Rocuronium 10(-4) M and 10(-2) M shifted the cumulative concentration-effect curves of PE to the right significantly (P<0.05). This relaxation effect of the aortic rings was not reversed with L-NAME or methylene blue pretreatment. However indomethacine shifted this curve to the right, and intracellular calcium release and extracellular calcium influx decreased significantly (P<0.05). CONCLUSIONS: From the results obtained with this experiment, it is concluded that the relaxation effects of rocuronium is not endothelium dependent and in part, is related with cyclooxygenase inhibition. Rocuronium inhibited intracelluar calcium release and extracelluar calcium influx.

Effects of Calcium and Potassium Channel Blockers on Local Anesthetics-Induced Relaxation in Rat Thoracic Aortic Rings / 대한마취과학회지

This study was designed to evaluate the effects of calcium and potassium channel blockers on local anesthetics-induced vascular relaxation of isolated rat thoracic aorta. In the presence of lidocaine and bupivacaine, the aortic rings previously contracted with phenylephrine(10(-4)M) were slightly contracted at the beginning of the administration of local anesthetics. But in the presence of tetracaine, aortic rings were not contracted at the beginnings. Verapamil, diltiazem and nifedipine in concentration of 10(-9)M to 10(-5)M produced cumulative concentration-dependent vasorelaxation significantly in the aortic rings previously contracted with phenylephrine(10(-4)M). In the presence of lidocaine, bupivacaine and tetracaine, verapamil, diltiazem and nifedipine in concentration of 10(-9)M to 10(-5)M caused dose-dependent vasorelaxation in aortic rings significantly. Tetraethylammonium HCl(TEA) in concentration of 10(-9)M to 10(-5)M did not produce dose-dependent vasorelaxation but slight contraction showed at the beginning of the administration. In the presence of lidocaine, bupivacaine, TEA in concentration of 10(-9)M to 10(-5)M did not produce vasorelaxation remarkably. But in the presence of tetracaine, TEA in concentration of 10(-9)M to 10(-5)M produced cumuIative concentration-dependent vasorelaxation significantly. These findings suggest that local anesthetics, especially tetracaine, which interact with calcium and potassium channel bleckers, lead to blockade of the sodium and calcium channels as well as potassium channels.

Endothelium dependent Effects of Halothane and Sevoflurane on Isolated Rabbit Aortic Vascular Rings / 대한마취과학회지

This study was aimed to elucidate the endothelium-dependent vascular effects of halothane and sevoflurane on rabbit aortic rings at two conventional concentrations(high induction and low maintenance concentration in human). Isometric tenslon was recorded in isolated aortic rings. Preparations of rabbit thoracic aorta were suspended in Krebs' buffer and aerated with 95% O2 and 5% CO2. One set of the rings had intact endothelium and the other set of the rings had endothelium mechanically denuded. In the first experiments, the rings were precontracted with norepinephrine(NE) of 10-7 M. After tension was stabilized in 10~15 minutes following NE, halothane(1, 2%) or sevoflurane(2, 4%) was bubbled with O2/CO2 gas mixture at increasing concentrations. In the second experiment, O2/CO2 gas mixture only(control rings), halothane 2% or sevoflurane 4 % with O2/CO2, gas mixture was bubbled for 10(-7) minutes prior to and during contraction with NE of 10M. After tension was stabilized following NE, acetylcholine(10(-8)-10(-6) M) was added cumulatively. In the third experiment, the procedure was as same as the second experiment except for that acetylcholine(10(-8)-10(-6) M) was substitued for nitroglycerin (10(-9)-10(-6) M) . The present study demonstated that both of halothane and sevoflurane at high concentration caused a vasoconstriction to 110.7+/-4.2% and 122.4+/-8.4% in vascular rings with intact endothelium, and 106.1+/-1.9% and 118.3+/-3.5% in vascular rings with denuded endothelium, respectively, compared to each control value of 100%. Furthermore, halothane and sevoflurane attenuated the acetylcholine induced relaxing response in NE-precontracted vascular rings with intact endothelium, but did not affect any change of tension in vascular rings with denuded endothelium. Halothane and sevoflurane did not attenuate the nitroglycerin induced relaxing response in NE-precontracted vascular rings with both intact and denuded endothelium. In conclusion, halothane and sevoflurane at high concentration has vasoconstrictory effects on vascular smooth muscles in rabbit aortic rings regardless of presence of endothelium and also attenuated the endothelium-dependent relaxation.

Puerarin protects high glucose-induced injury of vascular relaxation by activation of heme oxygenase-1 / 中国病理生理杂志

AIM:To investigate the effect of puerarin on acute high glucose-induced attenuation of ACh relaxation in isolated rat aortic rings, and to elucidate its underlying mechanism. METHODS: The thoracic aortic rings with endothelium of male Sprague-Dawley rats were mounted on a bath system. Isometric relaxation of aortic rings was measured. RESULTS: ① After incubation with high concentration of glucose (44 mmol/L), the vascular relaxation responses to ACh decreased. ② After coincubation with puerarin (10-10-10-8 mol/L) and high glucose, the high glucose-induced attenuation of ACh relaxation responses of artery was partly inhibited in a dose-dependent manner. ③ After incubation with puerarin for 2 h, the HO-1 activity of thoracic aorta increased. ZnPPIX (an inhibitor of heme oxygenase-1) abrogated the protective effect of puerarin. CONCLUSION: Puerarin prevents the acute high glucose-induced attenuation of endothelium-dependent relaxation in aortic rings. The mechanism might be involved in the activation of heme oxygenase-1.

EFFECTS OF TETRANDRINE AND NEFERINE ON THE PHENYLEPHRINE-INDUCED CONTRACTIONS IN RAT AORTIC RINGS / 中国药理学通报

The effects of tetrandrine and neferine on the phenylephrine-induced contractions were studied in Sprague-Dawley rat aortic rings. It was found that both tetrandrine and neferine ( 2?10-5 mol/L ) markedly inhibited phase I ( release of intracellular calcium) and phase II (entry of extracellular calcium) contractions after a 20 min incubation. After a shorter incubation period, tetrandrine and nefrine inhibited only the phase II contractions. Compared with tetrandrine, neferine exhibited slower and weaker effects

Effect of N-n-butyl haloperidol iodide on potassium channel in smooth muscle cells and rings of rat aorta / 中国药理学通报

AIM To investigate the effect of N n butyl haloperidol iodide (F 2) on potassium currents in enzymatically isolated vascular smooth muscle cells (VSMC) from thoracic aortas and the effect of F 2 on aortic rings of rat. METHODS The whole cell patch clamp technique and the contraction of rats thoracic aortic rings were used in experiments. RESULTS The outward currents were observed when holding potential was -40 mV and the cell was depolarized from -30 mV to +100 mV (in 10 mV increase) for 400 ms. At the point of the test potential of +70 mV, solutions of F 2 (0 1,1, 5 ?mol?L -1 ) were added into bath (external) solution, which led to the increase of the outward currents from (229?28)pA,(226?57)pA and(228?42) pA to (354?29) pA ( n =6, P