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1.
Lett Appl Microbiol ; 63(3): 202-9, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27248357

RESUMO

UNLABELLED: Fusarium oxysporum f. sp. lycopersici (Fol) causes tomato wilt. Based on the difference in pathogenicity towards tomato cultivars, Fol is classified into three races. In this study, a rapid method is developed for the detection and discrimination of Fol race 1 using a loop-mediated isothermal amplification (LAMP) assay with two primer sets targeting a region of the nucleotide sequence of the SIX4 gene specific for race 1 and a primer set targeting the SIX5 gene, conserved in all known Fol isolates. Upon LAMP reaction, amplification using all three primer sets was observed only when DNA of Fol race 1 was used as a template, and not when DNA of other Fol races or other fungal species was used. This method could detect 300 fg of Fol race 1 DNA, a 100-fold higher sensitivity than that obtained by conventional PCR. The method can also detect DNA extracted from soil artificially infested with Fol race 1. It is now possible to detect Fol race 1 in colonies and infected tomato stems without DNA isolation. This method is a rapid and simple tool for discrimination of Fol race 1. SIGNIFICANCE AND IMPACT OF THE STUDY: This study developed a loop-mediated isothermal amplification (LAMP) assay for detection and differentiation of Fusarium oxysporum f. sp. lycopersici (Fol) race 1 by using three primer sets targeting for the SIX4 and SIX5 genes. These genes are present together only in Fol race 1. This method can detect Fol race 1 in infected tomato stems without DNA extraction, affording an efficient diagnosis of Fusarium wilt on tomatoes in the field.


Assuntos
Fusarium/genética , Fusarium/isolamento & purificação , Doenças das Plantas/microbiologia , Solanum lycopersicum/microbiologia , Sequência de Bases , Primers do DNA/genética , Fusarium/classificação , Técnicas de Amplificação de Ácido Nucleico , Microbiologia do Solo
2.
Nature ; 452(7185): 332-5, 2008 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-18354478

RESUMO

Equal amounts of matter and antimatter are predicted to have been produced in the Big Bang, but our observable Universe is clearly matter-dominated. One of the prerequisites for understanding this elimination of antimatter is the nonconservation of charge-parity (CP) symmetry. So far, two types of CP violation have been observed in the neutral K meson (K(0)) and B meson (B(0)) systems: CP violation involving the mixing between K(0) and its antiparticle (and likewise for B(0) and ), and direct CP violation in the decay of each meson. The observed effects for both types of CP violation are substantially larger for the B(0) meson system. However, they are still consistent with the standard model of particle physics, which has a unique source of CP violation that is known to be too small to account for the matter-dominated Universe. Here we report that the direct CP violation in charged B(+/-)-->K(+/-)pi(0) decay is different from that in the neutral B(0) counterpart. The direct CP-violating decay rate asymmetry, (that is, the difference between the number of observed B(-)-->K(-)pi(0) event versus B(+)-->K(+) pi(0) events, normalized to the sum of these events) is measured to be about +7%, with an uncertainty that is reduced by a factor of 1.7 from a previous measurement. However, the asymmetry for versus B(0)-->K(+)pi(-) is at the -10% level. Although it is susceptible to strong interaction effects that need further clarification, this large deviation in direct CP violation between charged and neutral B meson decays could be an indication of new sources of CP violation-which would help to explain the dominance of matter in the Universe.

3.
Phys Rev Lett ; 97(25): 251802, 2006 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-17280341

RESUMO

We present the first evidence of the decay B- --> tau- nu(tau), using 414 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics and measure the branching fraction to be B(B- --> tau- nu(tau)) = (1.79(-0.49) +0.56(stat)(-0.51) +0.46(syst)) x 10(-4). This implies that fB = 0.229(-0.031) +0.036(stat)(-0.037) +0.034(syst) GeV and is the first direct measurement of this quantity.

4.
Phys Rev Lett ; 94(18): 181803, 2005 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-15904360

RESUMO

We report the observation of the decay B0-->pi(0)pi(0), using a 253 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) collider. The measured branching fraction is B(B0-->pi(0)pi(0))=(2.3(+0.4+0.2)(-0.5-0.3))x10(-6), with a significance of 5.8 standard deviations including systematic uncertainties. We also make a measurement of the direct CP violating asymmetry in this mode.

5.
Phys Rev Lett ; 93(19): 191802, 2004 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-15600826

RESUMO

We report evidence for direct CP violation in the decay B0-->K+pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) BB pairs we observe a B-->K+/-pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K+pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+-->K+pi(0) and B+-->pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K+pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05

6.
Phys Rev Lett ; 93(2): 021601, 2004 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-15323897

RESUMO

We report the first observation of CP violation in B0-->pi(+)pi(-) decays based on 152x10(6) gamma (4S)-->BB decays collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We reconstruct a B0-->pi(+)pi(-) CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two B meson decay points, we obtain A(pipi)=+0.58+/-0.15(stat)+/-0.07(syst) and S(pipi)=-1.00+/-0.21(stat)+/-0.07(syst). We rule out the CP-conserving case, A(pipi)=S(pipi)=0, at a level of 5.2 standard deviations. We also find evidence for direct CP violation with a significance at or greater than 3.2 standard deviations for any S(pipi) value.

7.
Phys Rev Lett ; 92(17): 171802, 2004 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-15169139

RESUMO

We have performed a search for the lepton-flavor-violating decay tau-->microgamma using a data sample of 86.3 fb(-1) accumulated by the Belle detector at KEK. No evidence for a signal is seen, and we set an upper limit for the branching fraction of B(tau-->microgamma)<3.1 x 10(-7) at the 90% confidence level.

8.
Phys Rev Lett ; 91(26 Pt 1): 261601, 2003 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-14754037

RESUMO

We report the observation of the flavor-changing neutral current decay B-->K(*)l(+)l(-) and an im-proved measurement of the decay B-->Kl(+)l(-), where l represents an electron or a muon, with a data sample of 140 fb(-1) accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. The results for the branching fractions are B(B-->K(*)l(+)l(-))=(11.5(+2.6)(-2.4)+/-0.8+/-0.2)x10(-7) and B(B-->Kl(+)l(-))=(4.8(+1.0)(-0.9)+/-0.3+/-0.1)x10(-7), where the first error is statistical, the second is systematic and the third is from model dependence.

9.
Phys Rev Lett ; 91(26 Pt 1): 261801, 2003 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-14754039

RESUMO

We report evidence for the decay B0-->pi(0)pi(0). The analysis is based on a data sample of 152x10(6) BBmacr; pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We detect a signal for B0-->pi(0)pi(0) with a significance of 3.4 standard deviations, and measure the branching fraction to be [1.7+/-0.6(stat)+/-0.2(syst)]x10(-6).

10.
Phys Rev Lett ; 91(26 Pt 1): 261602, 2003 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-14754038

RESUMO

We present an improved measurement of CP-violation parameters in B0-->phiK(0)(S), K(+)K(-)K(0)(S), and eta(')K(0)(S) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the three modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. We find that the observed CP asymmetry in the B-->phiK(0)(S) decay differs from the standard model (SM) expectation by 3.5 standard deviations, while the other cases are consistent with the SM.

11.
Phys Rev Lett ; 91(26 Pt 1): 262002, 2003 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-14754042

RESUMO

We report the first observation of the B-->Dmacr;D(sJ)(2317) and B-->Dmacr;D(sJ)(2457) decays based on 123.8x10(6) BBmacr; events collected with the Belle detector at KEKB. We observe the D(sJ)(2317) decay to D(s)pi(0) and the D(sJ)(2457) decay to the D(*)(s)pi(0) and D(s)gamma final states. We also set 90% C.L. upper limits for the decays D(sJ)(2317)-->D(*)(s)gamma, D(sJ)(2457)-->D(*)(s)gamma, D(sJ)(2457)-->D(s)pi(0), and D(sJ)(2457)-->D(s)pi(+)pi(-).

12.
Phys Rev Lett ; 91(26 Pt 1): 262001, 2003 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-14754041

RESUMO

We report the observation of a narrow charmoniumlike state produced in the exclusive decay process B+/--->K+/-pi(+)pi(-)J/psi. This state, which decays into pi(+)pi(-)J/psi, has a mass of 3872.0+/-0.6(stat)+/-0.5(syst) MeV, a value that is very near the M(D0)+M(D(*0)) mass threshold. The results are based on an analysis of 152M B-Bmacr; events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The signal has a statistical significance that is in excess of 10sigma.

13.
Jpn Circ J ; 63(8): 617-23, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10478812

RESUMO

The plasma level of endothelin-1 (ET-1) increases in several cardiovascular disorders. The present study examined whether threshold doses of ET-1 affect vascular tone and autoregulatory vasodilation during a reduction in perfusion pressure in the coronary microcirculation in vivo. In anesthetized open-chest dogs, arterial microvessels in the epimyocardium were observed through a microscope equipped with a floating objective. In 6 dogs, ET-1 (10(-13) to 10(-8)mol/L) was superfused onto the epimyocardium in a cumulative fashion. In another set of dogs (n= 16), the perfusion pressure of the observed vascular bed was reduced to 60 mmHg (mild stenosis) and to 40 mmHg (severe stenosis) by a hydraulic occluder, and the microvascular responses were observed in the presence (n=9) or absence (n=7) of ET-1 (10(-12) or 10(-11) mol/L). ET-1 > or =10(-11) mol/L constricted coronary arterioles (< or =100 microm in diameter) and small arteries (>100 microm in diameter) in a dose-dependent fashion. ET-1 of 10(-12) mol/L affected neither the basal diameters nor the dilation of vessels during the pressure reduction. ET-1 of 10(-11) mol/L decreased the diameters of arterioles and small arteries before and during the mild and severe stenosis. However, ET-1 did not attenuate the percentage dilation of arterioles from the baseline in response to the mild and severe stenosis. The data indicates the following: (1) ET-1 at doses > or =10(-11) mol/L similarly constricts coronary arterioles and small arteries; (2) ET-1 at 10(-11) mol/L, which is slightly higher than the pathophysiological plasma level, increases the basal vascular tone, but does not attenuate the autoregulatory vasodilation of the coronary microcirculation.


Assuntos
Veias Cerebrais/fisiologia , Circulação Coronária/efeitos dos fármacos , Endotelina-1/farmacologia , Vasodilatação/efeitos dos fármacos , Animais , Artérias , Arteríolas/efeitos dos fármacos , Arteríolas/fisiologia , Gasometria , Capilares/efeitos dos fármacos , Capilares/fisiologia , Doença das Coronárias , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/fisiologia , Cães , Relação Dose-Resposta a Droga , Endotelina-1/administração & dosagem , Feminino , Hemodinâmica , Homeostase/fisiologia , Concentração de Íons de Hidrogênio , Masculino , Microcirculação/efeitos dos fármacos , Vasoconstrição , Vasodilatação/fisiologia
14.
Heart Vessels ; 12(2): 60-6, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9403309

RESUMO

To test the hypothesis that anti-atherogenicity in women exerts beneficial effects to prevent restenosis formation after coronary angioplasty, we studied 493 men (988 lesions) and 81 women (159 lesions), aged 40-60 years, who had undergone successful balloon angioplasty and had follow-up angiography, 4.9 +/- 4.1 months later. We compared the extent of restenosis between men and women, and between pre- and post-menopausal women, which was assessed by a categorical definition of restenosis (more than 50% diameter stenosis at follow-up) and by percent diameter measured immediately after angioplasty and at follow-up. Hypertension was more frequent in women and a significantly lower percentage of women smoked. In women, the levels of total cholesterol and low-density lipoprotein cholesterol were higher. The location of dilated lesions, frequency of angioplasty for lesions with chronic total occlusion, and frequency of emergency angioplasty in patients with unstable angina or acute myocardial infarction were similar in men and women. Restenosis formation, estimated by the categorical definition or percent diameter, did not differ between men and women, or between pre- and post-menopausal women. Menopausal status or sex was not an independent predictor of restenosis by multivariate analysis. Thus, the benefit of anti-atherogenicity in women does not play an important role in preventing restenosis after coronary angioplasty.


Assuntos
Angioplastia Coronária com Balão , Doença das Coronárias/terapia , Adulto , Fatores Etários , Constrição Patológica , Doença das Coronárias/sangue , Vasos Coronários/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva , Estudos Retrospectivos
15.
J Am Coll Cardiol ; 27(1): 30-7, 1996 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8522707

RESUMO

OBJECTIVES: This study sought to investigate the effect of coronary angioplasty on chronic hypoperfusion-induced endothelial dysfunction in patients with coronary heart disease. BACKGROUND: The endothelium is an important component for organ flow regulation. Ischemia with or without reperfusion is known to cause endothelial dysfunction. We tested the hypothesis that chronic hypoperfusion impairs endothelial function in the angiographically normal coronary artery segment distal to stenosis and that the impairment by chronic hypoperfusion is reduced by coronary angioplasty. METHODS: In 13 patients with stable angina pectoris, substance P (10, 30 and 100 pmol) and nitroglycerin (200 micrograms) were sequentially infused into the coronary artery in a cumulative manner on the day after coronary angioplasty. In 10 of these patients, vascular responses to these agents were again investigated 3 months after angioplasty. Changes in vascular diameter were evaluated in vessels located proximal and distal to the target lesion, both of which were angiographically normal, by performing computer-assisted quantitative coronary angiography. In five patients, the transstenotic pressure gradient was also measured with a pressure sensor-mounted guide wire before angioplasty. RESULTS: On the day after angioplasty, the magnitude of dilation by substance P in distal segments was significantly less than that in proximal segments and inversely correlated with the transstenotic pressure gradient (p < 0.05) and lesion stenosis (p < 0.05). There was no difference in nitroglycerin-induced vasodilation between the two vessel segment groups. Three months later, the impaired response to substance P in the distal segment was restored to normal. CONCLUSIONS: We conclude that chronic hypoperfusion impairs endothelium-dependent dilation of coronary artery distal to critical stenosis in patients with ischemic heart disease and that coronary angioplasty ameliorates the endothelial dysfunction within 3 months.


Assuntos
Angina Pectoris/fisiopatologia , Angina Pectoris/terapia , Angioplastia Coronária com Balão , Endotélio Vascular/fisiopatologia , Idoso , Angina Pectoris/diagnóstico por imagem , Angiografia Coronária , Vasos Coronários/efeitos dos fármacos , Relação Dose-Resposta a Droga , Seguimentos , Humanos , Injeções Intra-Arteriais , Masculino , Pessoa de Meia-Idade , Nitroglicerina/administração & dosagem , Variações Dependentes do Observador , Estudos Prospectivos , Análise de Regressão , Fatores de Risco , Volume Sistólico/fisiologia , Substância P/administração & dosagem , Vasodilatadores/administração & dosagem
16.
J Cardiovasc Pharmacol ; 26(4): 541-7, 1995 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8569213

RESUMO

We aimed to clarify the size dependency of nicorandil-induced dilation in coronary microcirculation and the involvement of adenosine triphosphate (ATP)-sensitive potassium channels. Coronary arterial microvessels were observed through a microscope equipped with a floating objective in anesthetized open-chest dogs (n = 29). Heart rate and mean aortic pressure were maintained at control level. In 16 dogs, nicorandil was infused into the coronary in a cumulative fashion (0.1, 1.0, 10, and 100 micrograms/kg/min, for 5 min for each dose). In 13 dogs, glibenclamide (10 microM) was topically applied onto the observed area, and nicorandil was similarly infused. Nicorandil dilated vessels < 100 microns in diameter at all applied doses in a dose-dependent manner. Glibenclamide abolished the dilation of these vessels at the lower two doses. Vessels > 100 microns in diameter dilated only at the two higher doses and the dilation was not affected by glibenclamide. These data suggest that the vessels < 100 microns are more sensitive to this agent than other size vessels, and that ATP-sensitive potassium channels are involved in the nicorandil-induced dilation of vessels smaller than 100 microns, whereas the dilation of other size vessels occurs independently of this channel.


Assuntos
Vasos Coronários/efeitos dos fármacos , Niacinamida/análogos & derivados , Canais de Potássio/efeitos dos fármacos , Vasodilatadores/farmacologia , Trifosfato de Adenosina , Análise de Variância , Animais , Glicemia/metabolismo , Circulação Coronária/efeitos dos fármacos , Vasos Coronários/ultraestrutura , Cães , Relação Dose-Resposta a Droga , Feminino , Glibureto/administração & dosagem , Glibureto/farmacologia , Hemodinâmica/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Hipoglicemiantes/farmacologia , Infusões Intra-Arteriais , Masculino , Niacinamida/farmacologia , Nicorandil
17.
Cardiovasc Res ; 28(12): 1780-6, 1994 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-7867030

RESUMO

OBJECTIVE: The aim was to clarify the site in the coronary microcirculation that is dilated by an ATP sensitive potassium channel opener, levcromakalim, and to examine whether the magnitude of dilatation is size dependent. METHODS: Coronary arterial microvessels were observed through an intravital microscope equipped with a floating objective in beating canine left ventricles in situ. Flow velocity of the left anterior descending coronary artery was measured with a suction-type Doppler probe. Heart rate and aortic pressure were maintained at control levels throughout the experiments. Three doses of levcromakalim (0.01-1.0 microgram.kg-1.min-1) or a single dose (1.0 microgram.kg-1.min-1) were infused into the coronary artery in groups, with or without intracoronary glibenclamide pretreatment (200 or 400 micrograms.kg-1). The effect of levcromakalim on different sized vessels was assessed by dividing them into three groups according to control diameter (small, internal diameter < 100 microns; medium, > or = 100, < 200 microns; large, > or = 200 microns). RESULTS: The lowest dose of levcromakalim dilated only the small vessels. The two higher doses dilated vessels of all sizes, but the magnitude of dilatation was greater in the small vessel group than in the other two groups. Coronary resistance significantly decreased dose dependently during the infusion of 0.1 and 1.0 microgram.kg-1.min-1 of levcromakalim. Pretreatment with glibenclamide markedly attenuated the levcromakalim induced dilatation of all vessel groups and the reduction in coronary vascular resistance. CONCLUSIONS: Levcromakalim heterogeneously dilates coronary arterial microvessels via the opening of ATP sensitive potassium channels, and small vessels are more sensitive to levcromakalim.


Assuntos
Benzopiranos/farmacologia , Vasos Coronários/efeitos dos fármacos , Canais de Potássio/efeitos dos fármacos , Pirróis/farmacologia , Vasodilatadores/farmacologia , Animais , Capilares/efeitos dos fármacos , Cromakalim , Cães , Relação Dose-Resposta a Droga , Glibureto/farmacologia , Hemodinâmica/efeitos dos fármacos , Microscopia de Fluorescência , Nitroprussiato/farmacologia , Resistência Vascular/efeitos dos fármacos
18.
Circ Res ; 75(3): 556-66, 1994 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7914838

RESUMO

GTP-binding regulatory proteins (G proteins) regulate various biological functions, but their participation in controlling coronary microvascular tone has not been established yet. The goal of the present study was to elucidate the role of pertussis toxin (PTX)-sensitive G protein in regulating coronary microvascular tone during autoregulation and ischemia. In 42 open-chest dogs, coronary arterial microvessels on the surface of the left ventricle were directly observed by epi-illuminated fluorescence microangiography using a floating objective system. PTX (300 ng/mL) was superfused onto the surface of the left ventricle for 2 hours to block Gi and G(o) protein in epimyocardial coronary microvessels in vivo. PTX superfusion caused no change in the resting diameters of microvessels and significantly blocked the vasoconstriction induced by BHT 920 (a selective alpha 2-agonist). After pretreatment with PTX or its vehicle, the left anterior descending coronary artery (LAD) was occluded by a hydraulic occluder to reduce coronary perfusion pressure (CPP) in a stepwise fashion. A mild stenosis (CPP, 60 mm Hg), a severe stenosis (CPP, 40 mm Hg), and complete occlusion were sequentially produced. Coronary flow velocity in the LAD distal to the stenotic site was continuously monitored. In both PTX and vehicle groups, flow velocity did not significantly decrease during mild stenosis, proving that transmural coronary autoregulatory function was well preserved in the preparation. During severe stenosis and complete occlusion, the coronary flow velocity significantly decreased. In the vehicle group, microvessels < 100 microns in inner diameter significantly dilated in response to the reduction in perfusion pressure (mild stenosis, 6.2 +/- 1.9%; severe stenosis, 21.1 +/- 4.4%; and complete occlusion, 16.8 +/- 5.9%; P < .05 versus baseline diameters). In the PTX group, microvessels did not dilate during each occlusion level (mild stenosis, -2.0 +/- 0.9%; severe stenosis, -3.9 +/- 1.9%; and complete occlusion, -13.4 +/- 2.9%; P < .05 versus vehicle group). PTX did not affect the microvascular dilation caused by nitroprusside. The present data indicate that PTX-sensitive G protein is crucially involved in microvascular control during autoregulation and ischemia.


Assuntos
Circulação Coronária/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Coração/fisiologia , Microcirculação/fisiologia , Isquemia Miocárdica/fisiopatologia , Toxina Pertussis , Fatores de Virulência de Bordetella/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Azepinas/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Dióxido de Carbono/sangue , Circulação Coronária/efeitos dos fármacos , Diástole , Cães , Feminino , Angiofluoresceinografia , Coração/efeitos dos fármacos , Coração/fisiopatologia , Ventrículos do Coração , Homeostase , Concentração de Íons de Hidrogênio , Masculino , Microcirculação/efeitos dos fármacos , Microcirculação/fisiopatologia , Nitroprussiato/farmacologia , Oxigênio/sangue , Pressão Parcial , Sístole , Fatores de Tempo
19.
Phys Rev B Condens Matter ; 49(21): 15429, 1994 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-10010673
20.
Circulation ; 89(1): 366-74, 1994 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8281672

RESUMO

BACKGROUND: Calcitonin gene-related peptide (CGRP) is a potent dilator of epicardial conduit vessels and is released during myocardial ischemia in humans. However, the effect of CGRP on coronary arterial microvessels is still unclear, and it is unknown if CGRP modulates the tone of coronary arterial microvessels during acute myocardial ischemia. METHODS AND RESULTS: Epimyocardial microvessels were observed through a microscope equipped with a floating objective system in anesthetized open-chest dogs. Heart rate and aortic pressure were maintained at control levels. Flow velocity of the left anterior descending coronary artery (LAD) was measured with a suction-cup Doppler probe. When CGRP was cumulatively infused into the LAD (0.05, 0.5, 5.0, and 50 pmol/kg per minute) or superfused (0.03, 0.3, 3.0, and 30 nmol/L) over the left ventricular surface, arterial control microvessels > 100 microns in diameter dilated dose dependently at dosages of 0.5 to 50 pmol/kg per minute (infused) or 0.3 to 30 nmol/L (superfused), but those < 100 microns dilated only at the highest dose, and those > 100 microns had greater dilation in both groups. Only the highest dose of CGRP (infused) significantly increased coronary flow. The superfusion of CGRP(8-37) (CGRP receptor antagonist, 300 nmol/L) did not affect the control diameters of coronary arterial microvessels but completely abolished CGRP-induced vasodilation at the same doses (infused and superfused). However, 300 nmol/L of CGRP(8-37) did not affect the response of coronary arterial microvessels to the LAD occlusion in any size. CONCLUSIONS: CGRP preferentially dilates the coronary arterial microvessels > 100 microns in diameter but has only a small effect on those < 100 microns. Endogenous CGRP does not modulate the tone of coronary arterial microvessels during acute myocardial ischemia in beating canine hearts.


Assuntos
Peptídeo Relacionado com Gene de Calcitonina/fisiologia , Circulação Coronária/fisiologia , Vasos Coronários/fisiologia , Isquemia Miocárdica/fisiopatologia , Vasodilatação/fisiologia , Animais , Calcitonina/farmacologia , Peptídeo Relacionado com Gene de Calcitonina/administração & dosagem , Peptídeo Relacionado com Gene de Calcitonina/farmacologia , Antagonistas do Receptor do Peptídeo Relacionado ao Gene de Calcitonina , Circulação Coronária/efeitos dos fármacos , Vasos Coronários/efeitos dos fármacos , Cães , Relação Dose-Resposta a Droga , Feminino , Masculino , Microcirculação/efeitos dos fármacos , Microcirculação/fisiologia , Fragmentos de Peptídeos/farmacologia , Vasodilatação/efeitos dos fármacos
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