Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium

Autores
Vila Petroff, Martín Gerardo; Aiello, Ernesto Alejandro; Palomeque, Julieta; Salas, Margarita Ana; Mattiazzi, Alicia Ramona
Año de publicación
2000
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
1 Cat ventricular myocytes loaded with [Ca²⁺]i- and pHi-sensitive probes were used to examine the subcellular mechanism(s) of the Ang II-induced positive inotropic effect. Ang II (1 μM) produced parallel increases in contraction and Ca²⁺] transient amplitudes and a slowly developing intracellular alkalisation. Maximal increases in contraction amplitude and Ca²⁺] transient amplitude were 163 ± 22 and 43 ± 8 %, respectively, and occurred between 5 and 7 min after Ang II administration, whereas pHi increase (0·06 ± 0·03 pH units) became significant only 15 min after the addition of Ang II. Furthermore, the inotropic effect of Ang II was preserved in the presence of Na⁺-H+ exchanger blockade. These results indicate that the positive inotropic effect of Ang II is independent of changes in pHi. 2 Similar increases in contractility produced by either elevating extracellular [Ca²⁺]] or by Ang II application produced similar increases in peak systolic Ca²⁺] indicating that an increase in myofilament responsiveness to Ca²⁺] does not participate in the Ang II-induced positive inotropic effect. 3 Ang II significantly increased the L-type Ca²⁺] current, as assessed by using the perforated patch-clamp technique (peak current recorded at 0 mV: -1·88 ± 0·16 pA pF⁻¹ in control vs. -3·03 ± 0·20 pA pF⁻¹ after 6-8 min of administration of Ang II to the bath solution). 4 The positive inotropic effect of Ang II was not modified in the presence of either KB-R7943, a specific blocker of the Na⁺-Ca²⁺] exchanger, or ryanodine plus thapsigargin, used to block the sarcoplasmic reticulum function. 5 The above results allow us to conclude that in the cat ventricle the Ang II-induced positive inotropic effect is due to an increase in the intracellular Ca2+ transient, an enhancement of the L-type Ca²⁺] current being the dominant mechanism underlying this increase.
Centro de Investigaciones Cardiovasculares
Materia
Ciencias Médicas
Ryanodine receptor
Internal medicine
Endocrinology
Inotrope
Contraction (grammar)
Chemistry
Myocyte
Thapsigargin
Angiotensin ii
Contractility
Calcium
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/127068

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oai_identifier_str oai:sedici.unlp.edu.ar:10915/127068
network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardiumVila Petroff, Martín GerardoAiello, Ernesto AlejandroPalomeque, JulietaSalas, Margarita AnaMattiazzi, Alicia RamonaCiencias MédicasRyanodine receptorInternal medicineEndocrinologyInotropeContraction (grammar)ChemistryMyocyteThapsigarginAngiotensin iiContractilityCalcium1 Cat ventricular myocytes loaded with [Ca²⁺]i- and pHi-sensitive probes were used to examine the subcellular mechanism(s) of the Ang II-induced positive inotropic effect. Ang II (1 μM) produced parallel increases in contraction and Ca²⁺] transient amplitudes and a slowly developing intracellular alkalisation. Maximal increases in contraction amplitude and Ca²⁺] transient amplitude were 163 ± 22 and 43 ± 8 %, respectively, and occurred between 5 and 7 min after Ang II administration, whereas pHi increase (0·06 ± 0·03 pH units) became significant only 15 min after the addition of Ang II. Furthermore, the inotropic effect of Ang II was preserved in the presence of Na⁺-H+ exchanger blockade. These results indicate that the positive inotropic effect of Ang II is independent of changes in pHi. 2 Similar increases in contractility produced by either elevating extracellular [Ca²⁺]] or by Ang II application produced similar increases in peak systolic Ca²⁺] indicating that an increase in myofilament responsiveness to Ca²⁺] does not participate in the Ang II-induced positive inotropic effect. 3 Ang II significantly increased the L-type Ca²⁺] current, as assessed by using the perforated patch-clamp technique (peak current recorded at 0 mV: -1·88 ± 0·16 pA pF⁻¹ in control vs. -3·03 ± 0·20 pA pF⁻¹ after 6-8 min of administration of Ang II to the bath solution). 4 The positive inotropic effect of Ang II was not modified in the presence of either KB-R7943, a specific blocker of the Na⁺-Ca²⁺] exchanger, or ryanodine plus thapsigargin, used to block the sarcoplasmic reticulum function. 5 The above results allow us to conclude that in the cat ventricle the Ang II-induced positive inotropic effect is due to an increase in the intracellular Ca2+ transient, an enhancement of the L-type Ca²⁺] current being the dominant mechanism underlying this increase.Centro de Investigaciones Cardiovasculares2000info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf189-203http://sedici.unlp.edu.ar/handle/10915/127068enginfo:eu-repo/semantics/altIdentifier/issn/0022-3751info:eu-repo/semantics/altIdentifier/issn/1469-7793info:eu-repo/semantics/altIdentifier/doi/10.1111/j.1469-7793.2000.00189.xinfo:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:30:38Zoai:sedici.unlp.edu.ar:10915/127068Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:30:39.166SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
title Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
spellingShingle Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
Vila Petroff, Martín Gerardo
Ciencias Médicas
Ryanodine receptor
Internal medicine
Endocrinology
Inotrope
Contraction (grammar)
Chemistry
Myocyte
Thapsigargin
Angiotensin ii
Contractility
Calcium
title_short Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
title_full Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
title_fullStr Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
title_full_unstemmed Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
title_sort Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
dc.creator.none.fl_str_mv Vila Petroff, Martín Gerardo
Aiello, Ernesto Alejandro
Palomeque, Julieta
Salas, Margarita Ana
Mattiazzi, Alicia Ramona
author Vila Petroff, Martín Gerardo
author_facet Vila Petroff, Martín Gerardo
Aiello, Ernesto Alejandro
Palomeque, Julieta
Salas, Margarita Ana
Mattiazzi, Alicia Ramona
author_role author
author2 Aiello, Ernesto Alejandro
Palomeque, Julieta
Salas, Margarita Ana
Mattiazzi, Alicia Ramona
author2_role author
author
author
author
dc.subject.none.fl_str_mv Ciencias Médicas
Ryanodine receptor
Internal medicine
Endocrinology
Inotrope
Contraction (grammar)
Chemistry
Myocyte
Thapsigargin
Angiotensin ii
Contractility
Calcium
topic Ciencias Médicas
Ryanodine receptor
Internal medicine
Endocrinology
Inotrope
Contraction (grammar)
Chemistry
Myocyte
Thapsigargin
Angiotensin ii
Contractility
Calcium
dc.description.none.fl_txt_mv 1 Cat ventricular myocytes loaded with [Ca²⁺]i- and pHi-sensitive probes were used to examine the subcellular mechanism(s) of the Ang II-induced positive inotropic effect. Ang II (1 μM) produced parallel increases in contraction and Ca²⁺] transient amplitudes and a slowly developing intracellular alkalisation. Maximal increases in contraction amplitude and Ca²⁺] transient amplitude were 163 ± 22 and 43 ± 8 %, respectively, and occurred between 5 and 7 min after Ang II administration, whereas pHi increase (0·06 ± 0·03 pH units) became significant only 15 min after the addition of Ang II. Furthermore, the inotropic effect of Ang II was preserved in the presence of Na⁺-H+ exchanger blockade. These results indicate that the positive inotropic effect of Ang II is independent of changes in pHi. 2 Similar increases in contractility produced by either elevating extracellular [Ca²⁺]] or by Ang II application produced similar increases in peak systolic Ca²⁺] indicating that an increase in myofilament responsiveness to Ca²⁺] does not participate in the Ang II-induced positive inotropic effect. 3 Ang II significantly increased the L-type Ca²⁺] current, as assessed by using the perforated patch-clamp technique (peak current recorded at 0 mV: -1·88 ± 0·16 pA pF⁻¹ in control vs. -3·03 ± 0·20 pA pF⁻¹ after 6-8 min of administration of Ang II to the bath solution). 4 The positive inotropic effect of Ang II was not modified in the presence of either KB-R7943, a specific blocker of the Na⁺-Ca²⁺] exchanger, or ryanodine plus thapsigargin, used to block the sarcoplasmic reticulum function. 5 The above results allow us to conclude that in the cat ventricle the Ang II-induced positive inotropic effect is due to an increase in the intracellular Ca2+ transient, an enhancement of the L-type Ca²⁺] current being the dominant mechanism underlying this increase.
Centro de Investigaciones Cardiovasculares
description 1 Cat ventricular myocytes loaded with [Ca²⁺]i- and pHi-sensitive probes were used to examine the subcellular mechanism(s) of the Ang II-induced positive inotropic effect. Ang II (1 μM) produced parallel increases in contraction and Ca²⁺] transient amplitudes and a slowly developing intracellular alkalisation. Maximal increases in contraction amplitude and Ca²⁺] transient amplitude were 163 ± 22 and 43 ± 8 %, respectively, and occurred between 5 and 7 min after Ang II administration, whereas pHi increase (0·06 ± 0·03 pH units) became significant only 15 min after the addition of Ang II. Furthermore, the inotropic effect of Ang II was preserved in the presence of Na⁺-H+ exchanger blockade. These results indicate that the positive inotropic effect of Ang II is independent of changes in pHi. 2 Similar increases in contractility produced by either elevating extracellular [Ca²⁺]] or by Ang II application produced similar increases in peak systolic Ca²⁺] indicating that an increase in myofilament responsiveness to Ca²⁺] does not participate in the Ang II-induced positive inotropic effect. 3 Ang II significantly increased the L-type Ca²⁺] current, as assessed by using the perforated patch-clamp technique (peak current recorded at 0 mV: -1·88 ± 0·16 pA pF⁻¹ in control vs. -3·03 ± 0·20 pA pF⁻¹ after 6-8 min of administration of Ang II to the bath solution). 4 The positive inotropic effect of Ang II was not modified in the presence of either KB-R7943, a specific blocker of the Na⁺-Ca²⁺] exchanger, or ryanodine plus thapsigargin, used to block the sarcoplasmic reticulum function. 5 The above results allow us to conclude that in the cat ventricle the Ang II-induced positive inotropic effect is due to an increase in the intracellular Ca2+ transient, an enhancement of the L-type Ca²⁺] current being the dominant mechanism underlying this increase.
publishDate 2000
dc.date.none.fl_str_mv 2000
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
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status_str publishedVersion
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url http://sedici.unlp.edu.ar/handle/10915/127068
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info:eu-repo/semantics/altIdentifier/issn/1469-7793
info:eu-repo/semantics/altIdentifier/doi/10.1111/j.1469-7793.2000.00189.x
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
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Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
dc.format.none.fl_str_mv application/pdf
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