scholarly journals Evaluation of the Possible Mechanisms of Antihypertensive Activity ofLoranthus micranthus: An African Mistletoe

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Bamidele A. Iwalokun ◽  
Sedoten A. Hodonu ◽  
Stella Nwoke ◽  
Olabisi Ojo ◽  
Phillip U. Agomo
Keyword(s):  
Nitric Oxide ◽  
Serum Lipid ◽  
Smooth Muscles ◽  
Inhibitory Effect ◽  
Rat Aorta ◽  
Lipid Profiles ◽  
Antihypertensive Activity ◽  
Ring Model ◽  
Aorta Ring ◽  
Hypertensive Activity

Loranthus micranthus (LM), also called African mistletoe is a major NigerianLoranthaceaeplant used traditionally to treat hypertension. The methanolic leaf extract of the plant (LMME) has been shown to elicit anti-hypertensive activity in rats but mechanism remains unclear. This study was undertaken to study the effect of LM on pressor-induced contraction of rat aorta smooth muscles and serum lipid profiles in mice. The LMME was partitioned to produce n-butanol (NBF-LMME), chloroform (CF-LMME), ethyl acetate (EAF-LMME) and water (WF-LMME) fractions. The median effective concentrations and maximum relaxation of the fractions were determined against epinephrine and KCl pre-contracted rat aorta ring model. Serum lipid profiles and nitric oxide (NO) were determined spectrophotometrically in mice administered per orally 250 mg/kg b.w. of each fraction for 21 days. Data were analyzed statistically. NBF-LMME elicited the highest dose-dependent inhibitory effect on rat aorta pre-contracted with norepinephrine and KCl, followed in decreasing order by WF-LMME > CF-LMME > EAF-LMME. Similar order of activity was observed in the ability of these fractions to inhibit elevation in artherogenic lipids, raise serum nitric oxide and reduce cardiac arginase in mice. We conclude the anti-hypertensive activity ofL. micranthusinvolve anti-artherogenic events, vasorelaxation, cardiac arginase reduction and NO elevation.

scholarly journals Magnetic-laser influence on the system of nitric oxide and contractile activity of smooth muscles of rat aorta under hypertension

2012 ◽  
Vol 58 (6) ◽  
pp. 36-47
Author(s):  
SM Fedorov ◽  
◽  
OV Baziliuk ◽  
AV Kotsiuruba ◽  
IuP Korkach ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Rat Aorta

Inhibition of nitrovasodilator- and acetylcholine-induced relaxation and cyclic GMP accumulation by the cytochrome P-450 substrate, 7-ethoxyresorufin

1992 ◽  
Vol 70 (9) ◽  
pp. 1297-1303 ◽  
Author(s):  
Brian M. Bennett ◽  
Bernard J. McDonald ◽  
Rita Nigam ◽  
Patrick G. Long ◽  
W. Craig Simon
Keyword(s):  
Nitric Oxide ◽  
Glyceryl Trinitrate ◽  
Cyclic Gmp ◽  
Guanylyl Cyclase ◽  
Competitive Inhibition ◽  
Direct Interaction ◽  
Inhibitory Effect ◽  
Rat Aorta ◽  
Endothelial Nitric Oxide ◽  
Cytochrome P 450

We examined the effect of the cytochrome P-450 substrate, 7-ethoxyresorufin (7-ER), and its corresponding product, resorufin, on nitrovasodilator- and endothelium-dependent relaxation of isolated rat aorta. The EC50 value for glyceryl trinitrate (GTN) induced relaxation was increased over 100-fold by 7-ER and less than 3-fold by resorufin. The EC50 value for sodium nitroprusside (SNP) induced relaxation was increased approximately 12-fold by 7-ER, acetylcholine (ACh) induced relaxation was abolished, and relaxation induced by isopropylnorepinephrine was not significantly affected. GTN-, SNP-, and ACh-induced increases in cyclic GMP accumulation were inhibited by 7-ER, as were basal cyclic GMP levels in endothelium-intact, but not endothelium-denuded tissues. 7-ER decreased GTN biotransformation in intact aorta and decreased the regioselective formation of glyceryl-1,2-dinitrate. The activation by GTN and SNP of aortic guanylyl cyclase in broken cell preparations was not affected by 7-ER, indicating that the inhibitory effect of 7-ER is probably not due to a direct interaction with guanylyl cyclase. The inhibitory effect of 7-ER on GTN-induced relaxation was not altered by the addition of superoxide dismutase, suggesting that 7-ER does not act by increasing superoxide anion concentration (which would serve to increase the degradation of nitric oxide (NO) formed during vascular GTN biotransformation). Our data provide further evidence for the role of the cytochrome P-450 – cytochrome P-450 reductase system in the biotransformation of GTN to an activator (presumably nitric oxide) of guanylyl cyclase. The data are consistent with a mode of action of 7-ER involving either competitive inhibition of vascular cytochrome P-450 or uncoupling of vascular cytochrome P-450 reductase from cytochrome P-450. The data also suggest that the cytochrome P-450 system facilitates NO release from SNP and that 7-ER has an inhibitory effect on endothelial nitric oxide synthase.Key words: glyceryl trinitrate, nitrovasodilators, cytochrome P-450, vascular smooth muscle, 7-ethoxyresorufin, endothelium, cyclic GMP.

Thiopental inhibits nitric oxide production in rat aorta

1999 ◽  
Vol 77 (12) ◽  
pp. 958-966 ◽  
Author(s):  
Carlos Castillo ◽  
Juan Asbun ◽  
Bruno Escalante ◽  
Carlos M Villalón ◽  
Pedro López ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Inhibitory Effect ◽  
Rat Aorta ◽  
Nitric Oxide Production ◽  
Nitric Oxide Synthesis ◽  
Oxide Production ◽  
Nitrite Production ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
Endothelium Dependent Relaxation

We studied whether thiopental affects endothelial nitric oxide dependent vasodilator responses and nitrite production (an indicator of nitric oxide production) elicited by acetylcholine, histamine, and A23187 in rat aorta (artery in which nitric oxide is the main endothelial relaxant factor). In addition, we evaluated the barbiturate effect on nitric oxide synthase (NOS) activity in both rat aorta and kidney homogenates. Thiopental (10-100 µg/mL) reversibly inhibited the endothelium-dependent relaxation elicited by acetylcholine, histamine, and A23187. On the contrary, this anesthetic did not modify the endothelium-independent but cGMP-dependent relaxation elicited by sodium nitroprusside (1 nM - 1 µM) and nitroglycerin (1 nM - 1 µM), thus excluding an effect of thiopental on guanylate cyclase of vascular smooth muscle. Thiopental (100 µg/mL) inhibited both basal (87.8 ± 14.3%) and acetylcholine- or A23187-stimulated (78.6 ± 3.9 and 39.7 ± 5.6%, respectively) production of nitrites in aortic rings. In addition the barbiturate inhibited (100 µg/mL) the NOS (45 ± 4 and 42.8 ± 9%) in aortic and kidney homogenates, respectively (measured as 14C-labeled citrulline production). In conclusion, thiopental inhibition of endothelium-dependent relaxation and nitrite production in aortic rings strongly suggests an inhibitory effect on NOS. Thiopental inhibition of the NOS provides further support to this contention.Key words: thiopental, rat aorta, endothelium-dependent relaxation, nitric oxide synthesis.

scholarly journals Endothelium-dependent relaxation of rat aorta to a histamine H3agonist is reduced by inhibitors of nitric oxide synthase, guanylate cyclase and Na+,K+-ATPase

1996 ◽  
Vol 5 (1) ◽  
pp. 69-74 ◽  
Author(s):  
D. M. Djuric ◽  
M. T. Nesic ◽  
I. Z. Andjelkovic
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Guanylate Cyclase ◽  
Relaxation Effect ◽  
Inhibitory Effect ◽  
Rat Aorta ◽  
Muscarinic Cholinergic ◽  
Oxide Synthase ◽  
Β Adrenergic Receptors ◽  
Endothelium Dependent Relaxation

The possible involvement of different effector systems (nitric oxide synthase, guanylate cyclase, β-adrenergic and muscarinic cholinergic receptors, cyclooxygenase and lipoxygenase, and Na+,K+-ATPase) was evaluated in a histamine H3receptor agonist-induced ((R)α-methylhistamine, (R)α-MeHA) endothelium-dependent rat aorta relaxation assay. (R)α-MeHA (0.1 nM – 0.01 mM) relaxed endothelium-dependent rat aorta, with a pD2value of 8.22 ± 0.06, compared with a pD2value of 7.98 ± 0.02 caused by histamine (50% and 70% relaxation, respectively). The effect of (R)α-MeHA (0.1 nM – 0.01 mM) was competitively antagonized by thioperamide (1, 10 and 30 nM) (pA2= 9.21 ± 0.40; slope = 1.03 ± 0.35) but it was unaffected by pyrilamine (100 nM), cimetidine (1 μM), atropine (10 μM), propranolol (1 μM), indomethacin (10 μM) or nordthydroguaiaretic acid (0.1 mM). Inhibitors of nitric oxide synthase, L-NG-monomethylarginine (L-NMMA, 10 μM) and NG-nitro-L-arginine methylester (L-NOARG, 10 μM) inhibited the relaxation effect of (R)α-MeHA, by approximately 52% and 70%, respectively). This inhibitory effect of L-NMMA was partially reversed by L-arginine (10 μM). Methylene blue (10 μM) and ouabain (10 μM) inhibited relaxation (R)α-MeHA-induced by approximately 50% and 90%, respectively. The products of cyclooxygenase and lipoxygenase are not involved in (R)α-MeHA-induced endothelium-dependent rat aorta relaxation nor are the muscarinic cholinergic and β-adrenergic receptors. The results also suggest the involvement of NO synthase, guanylate cyclase and Na+,K+-ATPase in (R)α-MeHA-induced endothelium-dependent rat aorta relaxation.

scholarly journals Vasorelaxant-Mediated Antihypertensive Effect of the Leaf Aqueous Extract from Stephania abyssinica (Dillon & A. Rich) Walp (Menispermaceae) in Rat

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Chamberlin Fodem ◽  
Elvine Pami Nguelefack-Mbuyo ◽  
Magloire Kanyou Ndjenda II ◽  
Albert Kamanyi ◽  
Télesphore Benoit Nguelefack
Keyword(s):  
Nitric Oxide ◽  
Heart Rate ◽  
Methylene Blue ◽  
Aqueous Extract ◽  
Calcium Release ◽  
Inhibitory Effect ◽  
Antihypertensive Activity ◽  
Phytochemical Analysis

Stephania abyssinica is a medicinal plant used in Cameroon alternative medicine to treat arterial hypertension (AHT). Previous in vitro studies demonstrated the endothelium nitric oxide-independent vasorelaxant property of the aqueous extract from Stephania abyssinica (AESA). But its effect on AHT is unknown. The present study was undertaken to explore other vasorelaxant mechanisms and to determine the antihypertensive effects of AESA in male Wistar rats. Phytochemical analysis of AESA was carried out using the liquid chromatography-mass spectrometry (LC-MS) method. The vasorelaxant effects of AESA (1-1000 μg/mL) were studied on rat isolated thoracic aorta rings, in the absence or presence of indomethacin (10 μM) or methylene blue (10 μM). The inhibitory effect of AESA on phenylephrine (PE, 10 μM) or KCl- (60 mM) induced contraction as well as the intracellular calcium release was also evaluated. The in vivo antihypertensive activity of AESA (43, 86, or 172 mg/kg/day) or captopril (20 mg/kg/day) administered orally was assessed in L-NAME- (40 mg/kg/day) treated rats. Blood pressure and heart rate (HR) were measured at the end of each week while serum or urinary nitric oxide (NO), creatinine, and glomerular filtration rate (GFR) were determined at the end of the 6 weeks of treatment, as well as histological analysis of the heart and the kidney. The LC-MS profiling of AESA identified 9 compounds including 7 alkaloids. AESA produced a concentration-dependent relaxation on contraction induced either by PE and KCl, which was significantly reduced in endothelium-denuded vessels, as well as in vessels pretreated with indomethacin and methylene blue. Moreover, AESA inhibited the intracellular Ca2+ release-induced contraction. In vivo, AESA reduced the AHT, heart rate (HR), and ventricular hypertrophy and increased serum NO, urine creatinine, and GFR. AESA also ameliorated heart and kidney lesions as compared to the L-NAME group. These findings supported the use of AESA as a potential antihypertensive drug.

Inhibitory effect of melatonin on nitric oxide synthase in rat enteric nervous system

2001 ◽  
Vol 120 (5) ◽  
pp. A176-A176
Author(s):  
P KOPPITZ ◽  
M STORR ◽  
D SAUR ◽  
M KURJAK ◽  
H ALLESCHER
Keyword(s):  
Nitric Oxide ◽  
Nervous System ◽  
Nitric Oxide Synthase ◽  
Enteric Nervous System ◽  
Inhibitory Effect ◽  
Oxide Synthase

Serum lipid profiles in competitive athletes

2007 ◽  
Vol 51 (-1) ◽  
pp. 28-31 ◽  
Author(s):  
Elżbieta Hübner-Woźniak ◽  
Marzena Malara ◽  
Zbigniew Prawecki
Keyword(s):  
Serum Lipid ◽  
Lipid Profiles ◽  
Competitive Athletes

Inhibitory effect of nitric oxide-donating aspirin against prostatic cancer angiogenesis in tumor-bearing mice

2010 ◽  
Vol 30 (5) ◽  
pp. 504-507
Author(s):  
Ji-wen CHENG ◽  
Qing-gui MENG ◽  
Hao-yuan LU ◽  
Zhi-rou WANG ◽  
Xian-zhong BAI
Keyword(s):  
Nitric Oxide ◽  
Prostatic Cancer ◽  
Inhibitory Effect ◽  
Tumor Bearing
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