OBJECTIVETo evaluate the possible vascular effects of an environment carcinogen benzo(a)pyrene (BaP).

METHODSThe cytotoxicit of BaP and rat liver S9 (0.25 mg/mL)-activated BaP were examined by MTT assay. Thoracic aortic rings were dissected from Sprague-Dawley rats. Contraction of aortic rings was induced by 60 mmol/L KCl or 10(-6) mol/L phenylephrine (PE) in an ex-vivo perfusion system after BaP (100 μmol/L) incubation for 6 h. [Ca(2+)](i) was measured using Fluo-4/AM. For in-vivo treatment, rats were injected with BaP for 4 weeks (10 mg/kg, weekly, i.p.).

RESULTSBaP (1-500 μm) did not significantly affect cell viability; S9-activated BaP stimulated cell proliferation. BaP did not affect the contractile function of endothelium-intact or -denuded aortic rings. BaP did not affect ATP-induced ([Ca(2+)](i)) increases in human umbilical vein endothelial cells. In BaP-treated rats, heart rate and the number of circulating inflammatory cells were not affected. Body weight decreased while blood pressure increased significantly. The maximum aortic contractile responses to PE and KCl and the maximum aortic relaxation response to acetylcholine were significantly decreased by 25.0%, 34.2%, and 10.4%, respectively.

CONCLUSIONThese results suggest, in accordance with its DNA-damaging properties, that metabolic activation is a prerequisite for BaP-induced cardiovascular toxicity.

Animals ; Aorta ; drug effects ; Benzo(a)pyrene ; pharmacology ; Calcium ; metabolism ; Endothelial Cells ; drug effects ; metabolism ; Humans ; Male ; Rats ; Vasoconstriction ; drug effects

The aim of this study was to elucidate the effects of anti-hypertensive drugs, nifedipine, furosemide, hydrochlorothiazide, captopril, and atenolol on DNA synthesis and proliferation of cultured rat aortic smooth muscle cells induced by fetal calf serum. Aortic smooth muscle cells from Sprague-Dawley rats were isolated, cultured, and seeded in multi-well plates. When confluent, cells were cultured in a conditioned medium without fetal calf serum. After 72 hours, cells were cultured in the medium retaining 10% fetal calf serum with or without anti-hypertensive drugs by increasing the concentration between 10(-8) and 10(-4) M. DNA synthesis was assessed by [3H]-thymidine uptake and proliferation by cell numbers using a hemocytometer. Nifedipine at a concentration of 10(-5) M and 5 x 10(-5) M inhibited serum-induced DNA synthesis significantly by 50.8% and 86.6%, respectively (p < 0.05). The results of cell numbers paralleled those of 3H-thymidine incorporation. Serum-induced DNA synthesis was also reduced by 32.6% at the highest dose of furosemide (10(-4) M), but there was no statistical significance. Hydrochlorothiazide, captopril, and atenolol did not show anti-proliferative effect throughout any of the doses. In conclusion, among the various anti-hypertensive drugs, nifedipine seems to be most beneficial in view of its direct inhibitory effect on DNA synthesis and proliferation of smooth muscle cells, as well as for its anti-hypertensive effect.
Animal ; Antihypertensive Agents/pharmacology* ; Aorta/metabolism* ; Aorta/drug effects* ; Cell Division/drug effects ; Cells, Cultured ; DNA/biosynthesis* ; Male ; Muscle, Smooth, Vascular/metabolism* ; Muscle, Smooth, Vascular/drug effects* ; Muscle, Smooth, Vascular/cytology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo examine the effect of cinobufacini on rat thoracic aorta and its mechanism.

METHODSIsolated rat thoracic aorta was perfused and isometric tension was recorded by organ bath technique before and after cinobufacini treatment.

RESULTCinobufacini induced contraction of isolated thoracic aorta with or without endothelium in a concentration-dependent manner (at concentration of 2.5,5.0,7.5,10.0 g/L). The vasoconstriction effect of cinobufacini was more potent in endothelium-denuded aorta ring [(16.3+/-3.39)%, (52.5+/-7.70)%, (60.9+/-8.84)%, (69.2+/-11.34)%] than in endothelium-intact aorta ring [(6.2+/-2.07)%, (14.7+/-4.91), (17.6+/-5.86)%, (20.3+/-6.78)% (P<0.01)]. Its contractile effect was attenuated in Ca(2+)-free solution (about 1/10 of that in buffer with 1.25 mmol/L CaCl(2)) or by the treatment with verapamil (10(-7)mol/L), an L-type calcium channel antagonist. Cinobufacini induced contraction on the endothelium-intact rat aorta was augmented by pretreatment with L-NAME (10(-4)mol/L), a nitric oxide synthase inhibitor.

CONCLUSIONCinobufacini contracts rat thoracic aorta by opening the voltage-dependent Ca(2+) channel and increasing Ca(2+) influx into vascular smooth muscle. Cinobufacini can also stimulate the release of vascular relaxant factor, nitric oxide, from the endothelium and thus antagonize cinobufacini-induced contraction.

Animals ; Aorta, Thoracic ; drug effects ; Bufanolides ; pharmacology ; Endothelium, Vascular ; drug effects ; metabolism ; In Vitro Techniques ; Male ; Nitric Oxide ; biosynthesis ; Rats ; Rats, Sprague-Dawley ; Vasoconstriction ; drug effects ; Vasoconstrictor Agents ; pharmacology

AIMTo investigate the mechanisms of vasodilatation of plant-derived estrogen biochanin A.

METHODSIsolated aortic ring preparations from Sprague-Dawley rats were suspended in individual organ baths. The tension was measured isometrically.

RESULTSBiochanin A at the range of 10(-9)-10(-4) mol/L provoked concentration-dependent and endothelium-independent relaxation of the rings constricted by phenylephrine (10(-5) mol/L). Biochanin A caused concentration-dependent relaxation of denuded rings precontracted with KCl (6 x 10(-2) mol/L). Glibenclamide (3 x 10(-6) mol/L), a selective inhibitor of ATP-sensitive potassium channels, and tetraethylammonium (5 x 10(-3) mol/L), a Ca2+ -activated K+ channel inhibitor, significantly attenuated the relaxation induced by biochanin A. The vasoconstriction induced by phenylephrine was decreased by biochanin A in Ca2+ -free medium.

CONCLUSIONThe endothelium-independent relaxation of thoracic aorta induced by biochanin A might be mediated by ATP-sensitive K+ channels, Ca2+ -activated K+ channels and intracellular Ca2+ release from sarcoplasmic reticulum.

Animals ; Aorta, Thoracic ; drug effects ; physiology ; Genistein ; pharmacology ; In Vitro Techniques ; KATP Channels ; metabolism ; Male ; Muscle, Smooth, Vascular ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley ; Vasodilation ; drug effects

AIMTo explore the effects of heme- heme oxygenase-1 (HO-1)-carbon monoxide(CO)-cyclic GMP (cGMP)on aortic vascular reactivity in endotoxemic rats and its molecular mechanism.

METHODSBy using isolated vascular ring tension detecting technique, cumulative responses of thoracic aortic rings (TARs)to phenylephrine (PE) were measured at 6 h after lipopolysaccharide administration. Effects on contractile responses to PE were measured under which the TARs were incubated with hemin (He, donor of CO), zinc-protoporphyrin-IX(ZnPP-IX, selective inhibitor of HO-1), or methylene blue (MB, inhibitor of guanylyl cyclase), respectively. The content of CO and the activity of HO-1 were measured. The protein and the gene expression of HO-1 were examined by Western blot and RT-PCR.

RESULTSContractile responses of TARs to cumulative doses of PE were depressed by pretreated with LPS. The hyporesponsiveness was partly reversed by incubation with ZnPP-IX and was restored to normal by incubation with MB in endotoxemic rats. Incubation with He could contribute to the vascular hyporeactivity. The content of CO, the activity and the protein and the gene expression of HO-1 were significantly increased in aorta of endotoxemic rats.

CONCLUSIONLPS could induce the HO-1 mRNA and the protein expression, the activity of HO-1 increase in aorta, lead to active the pathway of heme-HO-1-CO-cGMP, which is one of the important mechanisms of the vascular hyporeactivity in endotoxemic rats.

Animals ; Aorta ; drug effects ; metabolism ; Carbon Monoxide ; metabolism ; Cyclic GMP ; metabolism ; Heme Oxygenase (Decyclizing) ; metabolism ; Lipopolysaccharides ; adverse effects ; Male ; Phenylephrine ; pharmacology ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the role of dietary capsaicin in activating transient receptor potential vanilloid 1 (TRPV1) and thus influencing the vascular dysfunction mediated by high-fat diet and the potential mechanisms.

METHODSA total of 80 male C57BL/6J mice aged 10 weeks were equally divided into four groups, in which the mice were fed with normal diet (ND), normal diet plus capsaicin (NC), high-fat diet (HD), or high-fat diet plus capsaicin (HC) for 20 weeks. Tail-cuff blood pressure (BP), vascular function of mice aortic rings, expressions of voltage-gated potassium-channel Kv1.4, RhoA and Rho kinase in aorta were examined.

RESULTSCompared with ND group, both nitroglycerin [(18.9 +/- 13)% vs. 100%, P < 0.01] and acetylcholine [(26 +/- 12)% vs. 100%, P < 0.01] induced vasorelaxation of aortic rings were significantly reduced in HD group. Both endothelium dependent and independent aortic rings vasorelaxation in HC group were significantly improved compared with that in HD group [acetylcholine: (69 +/- 15)%; nitroglycerin: (46.5 +/- 6)%, P < 0.05], but still reduced compared with that in ND group (P < 0.05, P < 0.01). High fat diet induced the expression of RhoA and Rho kinase. Dietary capsaicin down-regulated the expression of RhoA and Rho kinase but up-regulated the expression of Kv1.4 in aorta in mice fed with normal or high fat diet (all P < 0.05).

CONCLUSIONDietary capsaicin can ameliorate vasorelaxation dysfunction mediated by high-fat diet. The potential mechanisms may be related with TRPV1 activation, which in turn stimulates potassium channel and inhibits RhoA and Rho kinase in the vasculature.

Animals ; Aorta ; drug effects ; metabolism ; physiology ; Capsaicin ; pharmacology ; Diet, High-Fat ; adverse effects ; Endothelium, Vascular ; metabolism ; physiology ; Male ; Mice ; Mice, Inbred C57BL ; TRPV Cation Channels ; drug effects ; Vasodilation ; drug effects ; physiology ; rho-Associated Kinases ; metabolism ; rhoA GTP-Binding Protein ; metabolism

OBJECTIVETo investigate the effect of betulinic acid (BA) on relaxation in isolated rat aortic rings and its antioxidant property on oxidative stress of blood vessels.

METHODSAortic rings were isolated and BA was cumulatively added into organ bath. Isometric tension of endothelium intact or endothelium denuded thoracic aortic rings previously contracted by phenylephrine (PE) was recorded. Then aortic rings were randomly divided into normal control group, BA control group, H(2)O(2) group and BA+H(2)O(2) group, after being previously contracted by PE, isometric tension of endothelium-dependent relaxation induced by Ach was recorded.

RESULTExposure of intact endothelium rings previously contracted by PE to BA at the concentrations of 10(-7) mol/L-10(-4) mol/L evoked a significant concentration dependent relaxation, which was inhibited by pretreatment with N omega-nitro-L-arginine methyl ester (L-NAME, 10(-4)mol/L), but not by indometacin (10(-5)mol/L). The pD2 value of BA was 5.24 ± 0.04, and the EC(50)value was 2.45 x 10(-6)mol/L. Exposure of endothelium denuded rings previously contracted by PE to BA did not affect the relaxation in isolated aortic rings. ACh induced a dose-dependent relaxation that was weakened by pretreatment with H(2)O(2) (5 10(-4) mol/L) for 15 min. The EC(50) of BA markedly attenuated the inhibition of relaxation induced by H(2)O(2).

CONCLUSIONBA can evoke a concentration-dependent relaxation in aortic rings previously contracted by PE, which may be mediated by NO. And the decrease of endothelium-dependent relaxation in rat aortic rings exposed to H(2)O(2) can be markedly attenuated by BA, which may be mediated by reducing oxidative stress and maintaining the activity of NO in aortic rings.

Animals ; Aorta ; drug effects ; metabolism ; physiology ; Endothelium, Vascular ; drug effects ; metabolism ; physiology ; Hydrogen Peroxide ; pharmacology ; In Vitro Techniques ; Nitric Oxide ; metabolism ; Oxidative Stress ; drug effects ; Rats ; Rats, Sprague-Dawley ; Triterpenes ; pharmacology ; Vasodilation ; drug effects ; Vasodilator Agents ; pharmacology

AIM: To investigate the effects of pinocembrin on angiotensin II (Ang II)-induced vascular contraction, and to explore its molecular mechanism of actions. METHODS: The isometric vascular tone was measured in rat thoracic aortic rings with denuded endothelium. Phosphorylation level of myosin phosphatase target unit 1 (MYPT1), and protein levels of Rho kinase 1 (ROCK1, ROKβ or p160ROCK) and angiotensin II type-1 receptor (AT1R) were determined by Western blot analysis. RESULTS: Pinocembrin produced a relaxant effect on endothelium-denuded aortic rings contracted by Ang II (100 nmol·L(-1)) in a dose-dependent manner. In endothelium-denuded aortic rings stimulated by Ang II, pretreatment with pinocembrin (25 and 100 μmol·L(-1)) for 20 min significantly attenuated MYPT1 phosphorylation and ROCK1 protein levels. Meanwhile, the protein level of AT1R in response to Ang II was not affected by pinocembrin in rat aortic rings. CONCLUSION These findings indicate that pinocembrin inhibits vasoconstriction induced by Ang II in rat endothelium-denuded aortic rings, and the mechanism at least in part, is due to the blockade of the RhoA/ROCK pathway.
Angiotensin II ; metabolism ; Animals ; Aorta ; drug effects ; enzymology ; metabolism ; physiopathology ; Flavanones ; pharmacology ; In Vitro Techniques ; Male ; Myocardial Contraction ; drug effects ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; drug effects ; Vasoconstriction ; drug effects ; rho-Associated Kinases ; antagonists & inhibitors ; genetics ; metabolism

OBJECTIVETo investigate the vasorelaxation effect of crocetin (CCT) and its mechanism.

METHODSIsolated aortic rings from Sprague-Dawley rats were mounted in the organ bath system. The tension of the aorta was recorded.

RESULTCCT significantly provoked concentration-dependent relaxation in both endothelium-intact and-denuded aortic rings pre-constricted by phenylephrine (10⁻⁵ mol/L), and the vasorelaxation in endothelium-intact aortic rings was stronger than that in endothelium-denuded ones. CCT had no significant effects on aortic rings pre-constricted with KCl (6 × 10⁻² mol/L). Pretreatment with eith L-NAME (10⁻⁴ mol/L), an inhibitor of nitric oxide synthase (NOS), or indomethacin (10⁻⁵ mol/L), an inhibitor of cyclooxygenase, for 30 min significantly attenuated the relaxation of endothelium-intact aortic rings induced by CCT. Besides, both tetraethylammonium (a Ca²(+)-activated K(+) channel inhibitor, 5 × 10⁻³ mol/L) and 4-aminopyridine (a voltage-sensitive K(+) channel inhibitor, 10⁻³ mol/L), but not the ATP-sensitive K(+) channel inhibitor glibenclamide (3 × 10⁻⁶ mol/L), significantly attenuated CCT-induced relaxation in endothelium-denuded aortic rings.

CONCLUSIONCCT had partial endothelium-dependent relaxation in rat aortas, which may be mediated by activating the endothelial NOS-NO and cyclooxygenase-prostacyclin pathways. The endothelium-independent relaxation in rat aortas induced by CCT may be mediated by Ca²(+)-activated K(+) channels and voltage-sensitive K(+) channels.

Animals ; Aorta, Thoracic ; drug effects ; metabolism ; physiology ; Carotenoids ; pharmacology ; Endothelium, Vascular ; drug effects ; metabolism ; In Vitro Techniques ; Male ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; metabolism ; Phenylephrine ; pharmacology ; Potassium Channel Blockers ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasodilation ; drug effects ; Vasodilator Agents ; pharmacology

OBJECTIVETo study the modulatory effect of sulfur dioxide (SO(2)) on the accumulation of collagen type I and type III in the wall of aorta during spontaneously hypertensive rat (SHR) vascular remodeling.

METHODSEight male Wistar Kyoto rats at the age of 4 weeks with normal blood pressure were used as a control group. And sixteen male SHRs at the age of 4 weeks were randomly divided into an SHR control group and SHR + Na(2)SO(3)/NaHSO(3) (SO(2) donor) group. Na(2)SO(3)/NaHSO(3) solution was injected intraperitoneally everyday to the rats in the SHR + Na(2)SO(3)/NaHSO(3) group. After 5 weeks, the systemic blood pressure was measured. The weight ratio of left ventricle to the whole heart was also measured. The rat aorta was dyed with Hart's method. The morphometric parameters including outer radius, lumen radius and the wall thickness were calculated by Leica workstation. The plasma level of SO(2) was determined by HPLC method. The expressions of collagen type I and type III in aorta were detected by immunohistochemistry.

RESULTS(1) Compared with the WKY rat control group, the systolic blood pressure increased by 53%, the weight ratio of left ventricle to the whole heart increased by 6% but the plasma level of SO(2) decreased by 44% for rats in the SHR group (P < 0.01 or P < 0.05). Compared with the SHR control group, the systolic blood pressure decreased by 26%, but the plasma level of SO(2) increased by 28% (all P < 0.01) for rats in the SHR + Na(2)SO(3)/NaHSO(3) group. (2) Compared with the WKY rats, the ratio of media to lumen radius increased by 28% for SHR. Compared with the SHR group, the ratio of media to lumen radius decreased by 10% (P < 0.01) in rats of the SHR + Na(2)SO(3)/NaHSO(3) group. (3) Compared with rats in the WKY control group, collagen type I expression increased by 10% for rats in the SHR group (P < 0.01). Compared with the SHR group, however, the expression decreased by 58% for rats in the SHR + Na(2)SO(3)/NaHSO(3) group (P < 0.01). (4) Compared with rats in the WKY control group, the expression increased by 13% for rats in the hypoxia SHR group (P < 0.01); however, compared with rats in the SHR group, the expression decreased by 8% in the rats of the SHR +Na(2)SO(3)/NaHSO(3) group (P < 0.01).

CONCLUSIONSIn the process of SHR vascular collagen remodeling in the rats, SO(2) could inhibit the abnormal accumulation of collagen type I and type III in the wall of aorta. This effect may be one of the mechanisms by which SO(2) ameliorates SHR vascular remodeling.

Animals ; Aorta, Thoracic ; drug effects ; metabolism ; physiopathology ; Blood Pressure ; drug effects ; Collagen ; metabolism ; Male ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Sulfur Dioxide ; pharmacology