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
- Institución
- Universidad Nacional de La Plata
- OAI Identificador
- oai:sedici.unlp.edu.ar:10915/127068
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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 Articulo http://purl.org/coar/resource_type/c_6501 info:ar-repo/semantics/articulo |
format |
article |
status_str |
publishedVersion |
dc.identifier.none.fl_str_mv |
http://sedici.unlp.edu.ar/handle/10915/127068 |
url |
http://sedici.unlp.edu.ar/handle/10915/127068 |
dc.language.none.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
info:eu-repo/semantics/altIdentifier/issn/0022-3751 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 http://creativecommons.org/licenses/by-nc-sa/4.0/ 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 189-203 |
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