Displaying publications 21 - 40 of 79 in total

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  1. Mechanism of vasorelaxation induced by 3'-hydroxy-5,6,7,4'-tetramethoxyflavone in the rats aortic ring assay
    Tan CS, Yam MF
    Naunyn Schmiedebergs Arch Pharmacol, 2018 06;391(6):561-569.
    PMID: 29552696 DOI: 10.1007/s00210-018-1481-9
    Previous studies have demonstrated that 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (TMF) content in Orthosiphon stamineus fractions correlate with its vasorelaxation activity. Even with the availability of previous studies, there is still very little information on the vasorelaxation effect of TMF, and few scientific studies have been carried out. Therefore, the present study was designed to investigate the vasorelaxation activity and mechanism of action of the TMF. The vasorelaxation activity and the underlying mechanisms of TMF were evaluated on thoracic aortic rings isolated from Sprague Dawley rats. TMF caused the relaxation of aortic rings with endothelium pre-contracted with phenylephrine. However, the vasorelaxant effect of TMF was significantly decreased in PE-primed endothelium-denuded and potassium chloride-primed endothelium-intact aortic rings. In the presence of Nω-nitro-L-arginine methyl ester, methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, indomethacin, tetraethylammonium, 4-aminopyridine, barium chloride, atropine and propranolol, the relaxation stimulated by TMF was significantly reduced. TMF was also found to reduce Ca2+ release from sarcoplasmic reticulum (via IP3R) and block calcium channels (VOCC). The present study demonstrates the vasorelaxant effect of TMF involves NO/sGC/cGMP and prostacyclin pathways, calcium and potassium channels and muscarinic and beta-adrenergic receptors.
    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/physiology
  2. Fulltext Fresh soy oil protects against vascular changes in an estrogen-deficient rat model: an electron microscopy study
    Adam SK, Das S, Othman F, Jaarin K
    Clinics (Sao Paulo), 2009;64(11):1113-9.
    PMID: 19936186 DOI: 10.1590/S1807-59322009001100012
    To observe the effects of consuming repeatedly heated soy oil on the aortic tissues of estrogen-deficient rats.
    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/ultrastructure
  3. Fulltext Antiangiogenic activity of sophorolipids extracted from refined bleached deodorized palm olein
    Kithur Mohamed S, Asif M, Nazari MV, Baharetha HM, Mahmood S, Yatim ARM, et al.
    Indian J Pharmacol, 2019 4 30;51(1):45-54.
    PMID: 31031467 DOI: 10.4103/ijp.IJP_312_18
    OBJECTIVES: Sophorolipids (SLs) are a group of surface-active glycolipids produced by a type of nonpathogenic yeast Candida bombicola in the presence of vegetable oil through fermentation technology. SLs have shown antitumor activity; however, the mechanism of action underlying the anticancer activity of SLs is poorly understood. This work evaluated the anticancer activity of SLs fermented from palm oil by exploring its antiangiogenic activity.

    MATERIALS AND METHODS: The SLs that were fermented and further characterized for their biochemical activities. Cytotoxicity study was performed to assess cytostatic properties. A series of in vitro and ex vivo angiogenesis assay was also carried out. The relative fold change in the expression of p53 mRNA by SLs was also studied.

    RESULTS: Altogether, the data show that SLs derived from palm oil fermentation process inhibited neovascularization in the ex vivo tissue segments and also the endothelial cell proliferation between 50% and 65% inhibition as a whole. The palm oil derived SLs also caused downregulation of the suppression level of vascular endothelial growth factor and also upregulate the p53 mRNA level. The analytical studies revealed the presence of high amount of phenolic compounds but with relatively weak antioxidant activity. The gas chromatography-mass spectrometry studies revealed abundant amount of palmitic and oleic acid, the latter an established antiangiogenic agent, and the former being proangiogenic.

    CONCLUSION: Therefore, it can be concluded from this study that SLs derived from fermented palm oil have potent antiangiogenic activity which may be attributed by its oleic acid component.

    Matched MeSH terms: Aorta, Thoracic/drug effects; Aorta, Thoracic/physiology
  4. Right-sided Aortic Arch with Aberrant Left Subclavian Artery from Kommerell's Diverticulum
    Mubarak MY, Kamarul AT, Noordini MD
    Iran J Radiol, 2011 Sep;8(2):103-6.
    PMID: 23329925
    A previously healthy 52-year-old man had a chest radiograph for medical check-up and found to have a right-sided aortic arch. Computed tomography of the thorax revealed a right-sided aortic arch with aberrant left subclavian artery originated from Kommerell's diverticulum. Barium swallow examination showed compression of the posterior wall of the esophagus. He was asymptomatic and no surgical intervention was performed.
    Matched MeSH terms: Aorta, Thoracic
  5. Fulltext Spiral CT angiography in an infant with a hypoplastic aortic arch
    Man Harun S, Faridah Y
    Biomed Imaging Interv J, 2006 Apr;2(2):e11.
    PMID: 21614223 MyJurnal DOI: 10.2349/biij.2.2.e11
    The advent of multislice computed tomography (CT) has revolutionised the performance of body CT and allowed the development of CT angiography (CTA). CTA is a robust and minimally invasive method of visualizing the arterial vascular system. The newer generation of multidetector scans has allowed for shorter scanning times with no respiratory misregistration at peak vascular opacification following peripheral contrast injection. The volume of data obtained from these scans can be further manipulated to generate two-dimensional (2D) and three-dimensional (3D) images with no increase in radiation to the patient. Hence, CTA has gained popularity and importance as the alternative diagnostic tool especially for ill patients in which conventional angiography is inadvisable.We present an infant with coarctation of the aorta and hypoplastic aortic arch, in which CT angiography was used to pinpoint the diagnosis. The CT findings were subsequently confirmed at surgery.
    Matched MeSH terms: Aorta, Thoracic
  6. Fulltext A non-surgical management of delayed diagnosis of an oesophageal perforation due to ingestion of okra: a case report
    Rosmadi Ismail, Ummi Affah Mahamad, Abdul Aziz Marwan
    Malaysian Journal of Medicine and Health Sciences, 2020;16(108):87-89.
    MyJurnal
    Oesophageal perforation is a not uncommon condition, yet it carries a high mortality rate and has been observed as the most grievous trauma to the digestive tract. Common causes include iatrogenic instrumentation, foreign-body swallowing, and physical injury. This report highlighted a case of oesophageal perforation complicated by formation of proximal descending aorta pseudoaneurysm as a result of okra ingestion. The patient was successfully treated with conservative treatment. The possible mechanism of oesophageal rupture, diagnosis, treatment, and other complica- tion will be further discussed.
    Matched MeSH terms: Aorta, Thoracic
  7. Fulltext Dysphagia caused by an aberrant right subclavian artery
    Radhiana, H., Ahmad Razali, M.R., Wan Ishlah, W.L.
    International Medical Journal Malaysia, 2011;10(1):43-45.
    MyJurnal
    An aberrant right subclavian artery is the commonest aortic arch anomaly. Majority of them were asymptomatic. An aberrant subclavian artery is a rare cause of dysphagia in adults. This condition is also known as dysphagia lusoria. We report a case of dysphagia in a 49-year-old woman from an aberrant right subclavian artery. Diagnosis of her condition was made with barium swallow and MDCT (multidetector computed tomography) scan. She was managed conservatively.
    Matched MeSH terms: Aorta, Thoracic
  8. Fulltext eComment: Trans-pericardial extra-anatomic aortic bypass for coarctation of the aorta
    Sachithanandan A, Badmanaban B
    Interact Cardiovasc Thorac Surg, 2011 Jul;13(1):100.
    PMID: 21697404 DOI: 10.1510/icvts.2010.265264A
    Matched MeSH terms: Aorta, Thoracic/surgery*
  9. Single stage treatment of complex aortic pathology (mega-aortic syndrome) using frozen elephant trunk technique
    Krishna Moorthy PS, Saat SA, Sakijan AS
    Med J Malaysia, 2019 02;74(1):94-96.
    PMID: 30846673
    This is a case report of single-stage total thoracic aortic repair by the frozen elephant trunk technique for a 75-yearold female with a complex aortic pathology of mega-aorta extending from the ascending aorta to the descending aorta. We used a Thora flex™ Hybrid device, a frozen elephant trunk device with four branched grafts and the distal stent graft. The distal stent graft was inserted into the downstream descending aorta via an aortic arch and positioned 15 cm beyond the left subclavian artery after total arch replacement had been performed using a four-branch graft. The postoperative course was unremarkable with no complications. A post procedural computed tomography scan demonstrated complete exclusion of the descending thoracic aneurysm without endoleak. Therefore, fixing the whole mega-aorta in a single stage using the frozen elephant trunk was effective and safe.
    Matched MeSH terms: Aorta, Thoracic/surgery*
  10. A rare complication of myocardial ischaemia following single-stage repair in a case of Berry syndrome
    Duyen MD, Haranal MY, Dillon J, Sivalingam S
    Interact Cardiovasc Thorac Surg, 2020 10 01;31(4):576-577.
    PMID: 32772077 DOI: 10.1093/icvts/ivaa126
    Berry syndrome is a rare congenital cardiac lesion consisting of a distal aortopulmonary window, the aortic origin of the right pulmonary artery (PA), intact ventricular septum and an interrupted or hypoplastic aortic arch. Different repair techniques have been described in the literature. We report a case of Berry syndrome, in whom myocardial ischaemia developed following direct implantation of the right PA to the main PA, which was resolved using an interposition tube graft.
    Matched MeSH terms: Aorta, Thoracic/surgery*
  11. Characterizing the mechanisms of insulin vasodilatation of normal and streptozotocin-induced diabetic rat aorta
    Subramaniam G, Achike FI, Mustafa MR
    J Cardiovasc Pharmacol, 2009 Apr;53(4):333-40.
    PMID: 19295443 DOI: 10.1097/FJC.0b013e31819fd4a7
    The mechanism by which insulin causes vasodilatation remains unclear, so we explored this in aortic rings from normal Wistar Kyoto and streptozotocin-induced diabetic rats. Insulin-induced relaxation of phenylephrine-contracted [endothelium (ED) intact or denuded] aortic rings was recorded in the presence or absence of various drug probes. Insulin relaxant effect was more in ED-intact than in-denuded tissues from normal or diabetic rats. l-NAME or methylene blue partially inhibited insulin effect in ED-intact but not the ED-denuded tissues, whereas indomethacin (cyclooxygenase inhibitor) had no effect on any of the tissues, indicating that insulin induces relaxation by ED-dependent and -independent mechanisms, the former via the NOS-cyclic guanosine monophosphate but not the cyclooxygenase pathway. The voltage-dependent K channel (KV) blocker (4-aminopyridine) inhibited insulin action in all the tissues (normal or diabetic, with or without ED), whereas the selective BKCa blocker, tetraethylammonium, inhibited it in normal (ED intact or denuded) but not in diabetic tissues, indicating that KV mediates insulin action in normal and diabetic tissues, whereas the BKCa mediates it only in normal tissues, with possible pathophysiologic absence in diabetic tissues. The inward rectifier K channel (Kir) blocker (barium chloride) significantly inhibited insulin effect only in ED-intact or -denuded diabetic tissues, whereas the KATP channel blocker, glibenclamide, inhibited it only in the ED-denuded diabetic tissues, suggesting that Kir channels mediate insulin-induced relaxation in ED-intact or -denuded diabetic tissues, whereas the KATP channel mediates it in ED-denuded diabetic tissues. All the agents combined did not abolish insulin action, suggestive of a direct vasodilatory effect. In conclusion, insulin causes vasodilatation in normal and diabetic tissues via ED-dependent and -independent mechanisms differentially modulated by K channels, some of which functions are altered in diabetes and thus are potential therapeutic targets.
    Matched MeSH terms: Aorta, Thoracic/drug effects*
  12. Right aortic arch with isolation of the left subclavian artery: a rare association with airway obstruction
    Yubbu P, Latiff HA, Adam Abbaker AM
    Cardiol Young, 2017 Apr;27(3):613-616.
    PMID: 27817752 DOI: 10.1017/S1047951116001840
    We present two interesting cases of isolated left subclavian artery from the pulmonary artery with symptoms of upper airway obstruction. The first patient had tetralogy of Fallot, pulmonary artery sling, bilateral superior caval veins, and left bronchial isomerism, suggesting heterotaxy syndrome. The second patient had a right aortic arch, isolated left subclavian artery, and bilateral arterial ducts. These two cases are interesting because of their rarity and uncommon presentation.
    Matched MeSH terms: Aorta, Thoracic/abnormalities*
  13. Effect of alpha lipoic acid on oxidative stress and vascular wall of diabetic rats
    Balkis Budin S, Othman F, Louis SR, Abu Bakar M, Radzi M, Osman K, et al.
    Rom J Morphol Embryol, 2009;50(1):23-30.
    PMID: 19221642
    PREMISES AND OBJECTIVES: Antioxidant plays an important role in preventing the progression of diabetes mellitus (DM) complications. The aim of the present study was to investigate the effect of alpha lipoic acid (ALA) supplementation on plasma lipid, oxidative stress and vascular changes in diabetic rats.
    Matched MeSH terms: Aorta, Thoracic/drug effects; Aorta, Thoracic/pathology; Aorta, Thoracic/physiopathology*; Aorta, Thoracic/ultrastructure
  14. Fulltext A detailed microscopic study of the changes in the aorta of experimental model of postmenopausal rats fed with repeatedly heated palm oil
    Adam SK, Das S, Jaarin K
    Int J Exp Pathol, 2009 Jun;90(3):321-7.
    PMID: 19563614 DOI: 10.1111/j.1365-2613.2009.00658.x
    Hypercholesterolaemia, increase in lipid peroxidation and hyperhomocysteinaemia may contribute to the pathogenesis of atherosclerosis. This study was performed to examine the effects of repeatedly heated palm oil mixed with 2% cholesterol diet on atherosclerosis in oestrogen-deficient postmenopausal rats. Ovariectomy causes disruption of tunica intima layer of the rat aorta simulating a postmenopausal condition in females. Twenty-four ovariectomized female Sprague-Dawley rats were divided into four groups. The control group received 2% cholesterol diet without palm oil. A diet with 2% cholesterol content fortified with fresh, once-heated and five-times-heated palm oil was given to the other treatment groups. The rats were sacrificed at the end of 4 months of study and the aortic arch tissue was processed for histomorphometry and electron microscopy. On observation, there was disruption of the intimal layer of the ovariectomized rat aorta. There was no obvious ultrastructural change in the aorta of the rats fed with fresh palm oil. The ultrastructural changes were minimal with once-heated palm oil, in which there was a focal disruption of the endothelial layer. The focal disruption was more pronounced with five-times-heated palm oil. The results of this study show that the ingestion of fresh palm oil may have a protective effect on the aorta but such a protective action may be lost when the palm oil is repeatedly heated. The study may be clinically important for all postmenopausal women who are susceptible to atherosclerosis.
    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/ultrastructure
  15. Mechanisms of the anti-hypertensive effect of Hibiscus sabdariffa L. calyces
    Ajay M, Chai HJ, Mustafa AM, Gilani AH, Mustafa MR
    J Ethnopharmacol, 2007 Feb 12;109(3):388-93.
    PMID: 16973321
    Previous studies have demonstrated the anti-hypertensive effects of Hibiscus sabdariffa L. (HS) in both humans and experimental animals. To explore the mechanisms of the anti-hypertensive effect of the HS, we examined the effects of a crude methanolic extract of the calyces of HS (HSE) on vascular reactivity in isolated aortas from spontaneously hypertensive rats. HSE relaxed, concentration-dependently, KCl (high K(+), 80 mM)- and phenylephrine (PE, 1 microM)-pre-contracted aortic rings, with a greater potency against the alpha(1)-adrenergic receptor agonist. The relaxant effect of HSE was partly dependent on the presence of a functional endothelium as the action was significantly reduced in endothelium-denuded aortic rings. Pretreatment with atropine (1 microM), L-NAME (10 microM) or methylene blue (10 microM), but not indomethacin (10 microM), significantly blocked the relaxant effects of HSE. Endothelium-dependent and -independent relaxations induced by acetylcholine and sodium nitroprusside, respectively, were significantly enhanced in aortic rings pretreated with HSE when compared to those observed in control aortic rings. The present results demonstrated that HSE has a vasodilator effect in the isolated aortic rings of hypertensive rats. These effects are probably mediated through the endothelium-derived nitric oxide-cGMP-relaxant pathway and inhibition of calcium (Ca(2+))-influx into vascular smooth muscle cells. The present data further supports previous in vivo findings and the traditional use of HS as an anti-hypertensive agent.
    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/physiopathology
  16. Vasorelaxant and chemical fingerprint studies of Citrus reticulatae pericarpium extracts
    Tan CS, Loh YC, Ch'ng YS, Ng CH, Yeap ZQ, Ahmad M, et al.
    J Ethnopharmacol, 2019 Mar 25;232:135-144.
    PMID: 30543913 DOI: 10.1016/j.jep.2018.12.014
    ETHNOPHARMACOLOGICAL RELEVANCE: Citrus reticulatae Pericarpium (Chen pi) was widely used as an important ingredient in the prescription of TCM to treat phlegm fluid retention type hypertension. Since Chen pi is involved in treatment as antihypertensive TCM formula, we have reasonable expectation in believing that it might possess vasorelaxant activity.

    AIM OF THE STUDY: This study is designed to investigate the vasorelaxant effect of Chen pi and to study its pharmacology effects.

    MATERIALS AND METHODS: The vasorelaxant effect of water extract of Chen pi (CRW) were evaluated on thoracic aortic rings isolated from Sprague Dawley rats. The fingerprint of Chen pi and the extracts were developed with quantification of hesperidin content by HPTLC.

    RESULTS: CRW exhibited the strongest vasorelaxant activity. CRW caused the relaxation of the phenylephrine pre-contracted aortic rings in the presence and absence of endothelium as well as in potassium chloride pre-contracted endothelium-intact aortic ring. The incubation of propranolol (β-adrenergic receptor blocker), atropine (muscarinic receptor blocker), Nω-nitro-L-arginine methyl ester (NO synthase inhibitor), ODQ (sGC inhibitor), indomethacin (COX inhibitor), 4-aminopyridine (KV blocker), barium chloride (Kir blocker), and glibenclamide (KATP blocker) significantly reduced the vasorelaxant effects of CRW. CRW was also found to be active in reducing Ca2+ releases from the sarcoplasmic reticulum and suppressing the voltage-operated calcium channels.

    CONCLUSION: The vasorelaxant effect of CRW on rat aorta involves NO/sGC, calcium and potassium channels, muscarinic and β-adrenergic receptors.

    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/physiology
  17. Underlying mechanism of vasorelaxant effect exerted by 3,5,7,2',4'-pentahydroxyflavone in rats aortic ring
    Tew WY, Tan CS, Asmawi MZ, Yam MF
    Eur J Pharmacol, 2020 Aug 05;880:173123.
    PMID: 32335091 DOI: 10.1016/j.ejphar.2020.173123
    Morin (3,5,7,2',4'-pentahydroxyflavone) is a yellow coloured natural flavonoid found in plants of the Moraceae family. This favonoid is easily sources from readily available fruits, vegetables and eve certain beverages. Among the sources that was identified, it is clear that morin is most abundantly found in almond, old fustic, Indian guava, and Osage orange. Multiple studies have suggested that morin has multiple therapeutic actions and possess potential to be a functional potent drug. Previous studies demonstrated that morin is capable of resolving deoxycorticosterone acetate-salt-induced hypertension and possess strong vasorelaxant properties. However, the exact mechanisms remains unknown. Therefore, this study is designed to investigate the in vitro mechanism of morin-induced vasorelaxant effects. The underlying mechanisms of morin's vasorelaxant activities were evaluated on thoracic aortic rings isolated from Sprague-Dawley rats. Results from the study demonstrated morin causing vasodilatory reaction in phenylephrine and potassium chloride pre-contracted endothelium-intact aortic rings with the effect being significantly affected in endothelium-denuded aortic rings. Pre-incubation of the aortic rings with ODQ (selective cGMP-independent sGC inhibitor), indomethacin (nonselective COX inhibitor), L-NAME (endothelial nitric oxide inhibitor), propranolol (β2-adrenegic receptors blocker), and atropine (muscarinic receptors blocker) significantly reduced the vasorelaxant effect of morin. It was also found to be able to reduce the intracellular calcium level by blocking VOCC and calcium intake from the extracellular environment and the intracellular release of calcium from the sarcoplasmic reticulum. The present study showed that the vasorelaxant effect of morin potentially involves the NO/sGC, muscarinic receptors, β2-adrenegic receptors, and calcium channels.
    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/physiology
  18. Chronic treatment with flavonoids prevents endothelial dysfunction in spontaneously hypertensive rat aorta
    Machha A, Mustafa MR
    J Cardiovasc Pharmacol, 2005 Jul;46(1):36-40.
    PMID: 15965352
    Flavonoids are known to possess cardioprotective properties. Vascular endothelial function is a surrogate marker for cardiovascular diseases, including hypertension. We have studied the effects of chronic flavonoid treatment on vascular endothelial functions in spontaneously hypertensive rats (SHR). Starting from 6-7 weeks old, SHR were given flavonoids (baicalein, flavone, or quercetin) orally (10 mg/kg, once daily) to the SHRs for 4 weeks. Aortas from all the flavonoid-treated animals showed remarkably higher endothelium-dependent relaxations to acetylcholine, to a similar extent as those pretreated with the angiotensin-converting enzyme inhibitor, captopril. However, in contrast to other experimental groups, flavone pretreatment also enhanced the endothelium-independent relaxations to sodium nitroprusside. In addition, treatment with either flavone or quercetin induced a significant attenuation in systolic blood pressure of the hypertensive animals. The present results suggest that chronic treatment with the flavonoids (baicalein, flavone, and quercetin) preserves vascular endothelial functions in hypertensive animals through several possible actions, including increasing endothelial nitric oxide production and bioavailability and reduction in blood pressure.
    Matched MeSH terms: Aorta, Thoracic/drug effects*; Aorta, Thoracic/physiopathology
  19. Vasodilator effect of Phlomis bracteosa constituents is mediated through dual endothelium-dependent and endothelium-independent pathways
    Khan AU, Ullah R, Khan A, Mustafa MR, Hussain J, Murugan DD, et al.
    Clin Exp Hypertens, 2012;34(2):132-9.
    PMID: 21967029 DOI: 10.3109/10641963.2011.601383
    This study describes the vasorelaxant potential of some pure compounds isolated from Phlomis bracteosa L. marrubiin, phlomeoic acid, and two new constituents labeled as RA and RB. In rat thoracic aortic rings denuded of endothelium, marrubiin, phlomeoic acid, RA, and RB caused relaxation of high K(+) (80 mM) and phenylephrine (1 μM)-induced contractions at the concentration range of 1.0-1000 μg/mL. Marrubiin, phlomeoic acid, RA, and RB concentration dependently (3.0-10 μg/mL) shifted the Ca(++) curves to the right obtained in Ca(++)-free medium. The vasodilator effect of marrubiin, phlomeoic acid, RA, and RB was partially blocked by N(ω)-nitro-L-arginine methyl ester in endothelium-intact aorta preparations. These results reveal that P. bracteosa constituents: marrubiin, phlomeoic acid, RA, and RB exhibit vasodilator action occurred via a combination of endothelium-independent Ca(++) antagonism and endothelium-dependent N(ω)-nitro-L-arginine methyl ester-sensitive nitric oxide-modulating mechanism.
    Matched MeSH terms: Aorta, Thoracic/drug effects; Aorta, Thoracic/physiology
  20. Fulltext A Pharmacological Examination of the Cardiovascular Effects of Malayan Krait (Bungarus candidus) Venoms
    Chaisakul J, Rusmili MR, Hodgson WC, Hatthachote P, Suwan K, Inchan A, et al.
    Toxins (Basel), 2017 03 29;9(4).
    PMID: 28353659 DOI: 10.3390/toxins9040122
    Cardiovascular effects (e.g., tachycardia, hypo- and/or hypertension) are often clinical outcomes of snake envenoming. Malayan krait (Bungarus candidus) envenoming has been reported to cause cardiovascular effects that may be related to abnormalities in parasympathetic activity. However, the exact mechanism for this effect has yet to be determined. In the present study, we investigated thein vivoandin vitrocardiovascular effects ofB. candidusvenoms from Southern (BC-S) and Northeastern (BC-NE) Thailand. SDS-PAGE analysis of venoms showed some differences in the protein profile of the venoms.B. candidusvenoms (50 µg/kg-100 µg/kg, i.v.) caused dose-dependent hypotension in anaesthetised rats. The highest dose caused sudden hypotension (phase I) followed by a return of mean arterial pressure to baseline levels and a decrease in heart rate with transient hypertension (phase II) prior to a small decrease in blood pressure (phase III). Prior administration of monovalent antivenom significantly attenuated the hypotension induced by venoms (100 µg/kg, i.v.). The sudden hypotensive effect of BC-NE venom was abolished by prior administration of hexamethonium (10 mg/kg, i.v.) or atropine (5 mg/kg, i.v.). BC-S and BC-NE venoms (0.1 µg/kg-100 µg/ml) induced concentration-dependent relaxation (EC50= 8 ± 1 and 13 ± 3 µg/mL, respectively) in endothelium-intact aorta. The concentration-response curves were markedly shifted to the right by pre-incubation with L-NAME (0.2 mM), or removal of the endothelium, suggesting that endothelium-derived nitric oxide (NO) is likely to be responsible for venom-induced aortic relaxation. Our data indicate that the cardiovascular effects caused byB. candidusvenoms may be due to a combination of vascular mediators (i.e., NO) and autonomic adaptation via nicotinic and muscarinic acetylcholine receptors.
    Matched MeSH terms: Aorta, Thoracic/drug effects; Aorta, Thoracic/physiology
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