The left ventricular contractility of the rat heart is modulated by changes in flow and a1-adrenoceptor stimulation

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dc.date.accessioned2011-03-14T14:38:38Z
dc.date.available2011-03-14T14:38:38Z
dc.identifier.citationVASSALLO, P. F. et al. The left ventricular contractility of the rat heart is modulated by changes in flow and a1-adrenoceptor stimulation. Braz J Med Biol Res, Ribeirão Preto, v. 31, n. 10, p. 1353-1359, out. 1998. Disponível em: <http://www.scielo.br/pdf/bjmbr/v31n10/3085c.pdf>. Acesso em: 7 fev. 2011.por
dc.identifier.doi10.1590/S0100-879X1998001000019
dc.identifier.issn1678-4510
dc.identifier.urihttp://repositorio.ufes.br/handle/10/610
dc.rightsopen accessen
dc.titleThe left ventricular contractility of the rat heart is modulated by changes in flow and a1-adrenoceptor stimulationpor
dc.typearticleen
dcterms.abstractMyocardial contractility depends on several mechanisms such as coronary perfusion pressure (CPP) and flow as well as on a1-adrenoceptor stimulation. Both effects occur during the sympathetic stimulation mediated by norepinephrine. Norepinephrine increases force development in the heart and produces vasoconstriction increasing arterial pressure and, in turn, CPP. The contribution of each of these factors to the increase in myocardial performance needs to be clarified. Thus, in the present study we used two protocols: in the first we measured mean arterial pressure, left ventricular pressure and rate of rise of left ventricular pressure development in anesthetized rats (N = 10) submitted to phenylephrine (PE) stimulation before and after propranolol plus atropine treatment. These observations showed that in vivo a1-adrenergic stimulation increases left ventricular-developed pressure (P<0.05) together with arterial blood pressure (P<0.05). In the second protocol, we measured left ventricular isovolumic systolic pressure (ISP) and CPP in Langendorff constant flow-perfused hearts. The hearts (N = 7) were perfused with increasing flow rates under control conditions and PE or PE + nitroprusside (NP). Both CPP and ISP increased (P<0.01) as a function of flow. CPP changes were not affected by drug treatment but ISP increased (P<0.01). The largest ISP increase was obtained with PE + NP treatment (P<0.01). The results suggest that both mechanisms, i.e., direct stimulation of myocardial a1-adrenoceptors and increased flow, increased cardiac performance acting simultaneously and synergistically.eng
dcterms.creatorVassallo, P. F.
dcterms.creatorStefanon, Ivanita
dcterms.creatorRossoni, Luciana Venturini
dcterms.creatorTucci, Paulo José Ferreira
dcterms.creatorVassallo, Dalton Valentim
dcterms.issued1998-10
dcterms.languageengen
dcterms.subjectFunção ventricular esquerdapor
dcterms.subjectPressão ventricularpor
dcterms.subjectFenilefrinapor
dcterms.subjectCirculação coronáriapor
dcterms.subjectRatos Wistarpor
dcterms.subjectPressão Arterialpor
dcterms.subjectVentricular function, leftpor
dcterms.subjectVentricular pressurepor
dcterms.subjectPhenylephrinepor
dcterms.subjectCoronary circulationpor
dcterms.subjectRats, Wistarpor
dcterms.subjectBlood pressurepor
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