Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System

Myocardial stretch is a well-known stimulus that leads to hypertrophy. Little is known, however, about the intracellular pathways involved in the transmission of myocardial stretch to the cytoplasm and nucleus. Studies in neonatal cardiomyocytes demonstrated stretch-induced release of angiotensin II...

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Detalles Bibliográficos
Autores principales: Cingolani, Horacio Eugenio, Álvarez, Bernardo Víctor, Ennis, Irene Lucía, Camilión de Hurtado, María Cristina
Formato: Articulo
Lenguaje:Inglés
Publicado: 1998
Materias:
Ciencias Médicas
stretch, myocardial
pH, intracellular
Na1/H1 exchange
angiotensin
endothelin
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/123622
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-123622
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Médicas
stretch, myocardial
pH, intracellular
Na1/H1 exchange
angiotensin
endothelin
spellingShingle Ciencias Médicas
stretch, myocardial
pH, intracellular
Na1/H1 exchange
angiotensin
endothelin
Cingolani, Horacio Eugenio
Álvarez, Bernardo Víctor
Ennis, Irene Lucía
Camilión de Hurtado, María Cristina
Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System
topic_facet Ciencias Médicas
stretch, myocardial
pH, intracellular
Na1/H1 exchange
angiotensin
endothelin
description Myocardial stretch is a well-known stimulus that leads to hypertrophy. Little is known, however, about the intracellular pathways involved in the transmission of myocardial stretch to the cytoplasm and nucleus. Studies in neonatal cardiomyocytes demonstrated stretch-induced release of angiotensin II (Ang II). Because intracellular alkalinization is a signal to cell growth and Ang II stimulates the Na + /H + exchanger (NHE), we studied the relationship between myocardial stretch and intracellular pH (pH i ). Experiments were performed in cat papillary muscles fixed by the ventricular end to a force transducer. Muscles were paced at 0.2 Hz and superfused with HEPES-buffered solution. pH i was measured by epifluorescence with the acetoxymethyl ester form of the pH-sensitive dye 2′,7′-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF-AM). Each muscle was progressively stretched to reach maximal developed force (L max ) and maintained in a length that was ≈92% L max (L i ). During the “stretch protocol,” muscles were quickly stretched to L max for 10 minutes and then released to L i ; pH i significantly increased during stretch and came back to the previous value when the muscle was released to L i . The increase in pH i was eliminated by (1) specific inhibition of the NHE (EIPA, 5 μmol/L), (2) AT 1 -receptor blockade (losartan, 10 μmol/L), (3) inhibition of protein kinase C (PKC) (chelerythrine, 5 μmol/L), (4) blockade of endothelin (ET) receptors with a nonselective (PD 142,893, 50 nmol/L) or a selective ET A antagonist (BQ-123, 300 nmol/L). The increase in pH i by exogenous Ang II (500 nmol/L) was also reduced by both ET-receptor antagonists. Our results indicate that after myocardial stretch, pH i increases because of stimulation of NHE activity. This involves an autocrine-paracrine mechanism in which protein kinase C, Ang II, and ET play crucial roles.
format Articulo
Articulo
author Cingolani, Horacio Eugenio
Álvarez, Bernardo Víctor
Ennis, Irene Lucía
Camilión de Hurtado, María Cristina
author_facet Cingolani, Horacio Eugenio
Álvarez, Bernardo Víctor
Ennis, Irene Lucía
Camilión de Hurtado, María Cristina
author_sort Cingolani, Horacio Eugenio
title Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System
title_short Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System
title_full Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System
title_fullStr Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System
title_full_unstemmed Stretch-Induced Alkalinization of Feline Papillary Muscle: An Autocrine-Paracrine System
title_sort stretch-induced alkalinization of feline papillary muscle: an autocrine-paracrine system
publishDate 1998
url http://sedici.unlp.edu.ar/handle/10915/123622
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AT alvarezbernardovictor stretchinducedalkalinizationoffelinepapillarymuscleanautocrineparacrinesystem
AT ennisirenelucia stretchinducedalkalinizationoffelinepapillarymuscleanautocrineparacrinesystem
AT camiliondehurtadomariacristina stretchinducedalkalinizationoffelinepapillarymuscleanautocrineparacrinesystem
bdutipo_str Repositorios
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