| The left ventricular contractility of the rat heart is modulated by changes in flow and alpha 1-adrenoceptor stimulation. | |
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MedLine Citation:
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PMID: 9876310 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Myocardial contractility depends on several mechanisms such as coronary perfusion pressure (CPP) and flow as well as on alpha 1-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 alpha 1-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 alpha 1-adrenoceptors and increased flow, increased cardiac performance acting simultaneously and synergistically. |
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Authors:
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P F Vassallo; I Stefanon; L V Rossoni; P J Tucci; D V Vassallo |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Brazilian journal of medical and biological research = Revista brasileira de pesquisas médicas e biológicas / Sociedade Brasileira de Biofísica ... [et al.] Volume: 31 ISSN: 0100-879X ISO Abbreviation: Braz. J. Med. Biol. Res. Publication Date: 1998 Oct |
Date Detail:
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Created Date: 1999-02-18 Completed Date: 1999-02-18 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8112917 Medline TA: Braz J Med Biol Res Country: BRAZIL |
Other Details:
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Languages: eng Pagination: 1353-9 Citation Subset: IM |
Affiliation:
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Departamento de Ciências Fisiológicas, Centro Biomédico, Universidade Federal do Espírito Santo, Vitória, Brasil. daltonv2@interlink.com.br |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic alpha-Agonists
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pharmacology Animals Blood Pressure Coronary Circulation / drug effects, physiology* Male Myocardial Contraction / drug effects, physiology* Phenylephrine / pharmacology Rats Rats, Wistar Receptors, Adrenergic, alpha-1 / physiology* Ventricular Function, Left / drug effects, physiology* Ventricular Pressure |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-Agonists; 0/Receptors, Adrenergic, alpha-1; 59-42-7/Phenylephrine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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