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

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 al...

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Autores principales:	Vila Petroff, Martín Gerardo, Aiello, Ernesto Alejandro, Palomeque, Julieta, Salas, Margarita Ana, Mattiazzi, Alicia Ramona
Formato:	Articulo
Lenguaje:	Inglés
Publicado:	2000
Materias:	Ciencias Médicas Ryanodine receptor Internal medicine Endocrinology Inotrope Contraction (grammar) Chemistry Myocyte Thapsigargin Angiotensin ii Contractility Calcium
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/127068
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

id	I19-R120-10915-127068
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 Ryanodine receptor Internal medicine Endocrinology Inotrope Contraction (grammar) Chemistry Myocyte Thapsigargin Angiotensin ii Contractility Calcium
spellingShingle	Ciencias Médicas Ryanodine receptor Internal medicine Endocrinology Inotrope Contraction (grammar) Chemistry Myocyte Thapsigargin Angiotensin ii Contractility Calcium Vila Petroff, Martín Gerardo Aiello, Ernesto Alejandro Palomeque, Julieta Salas, Margarita Ana Mattiazzi, Alicia Ramona Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
topic_facet	Ciencias Médicas Ryanodine receptor Internal medicine Endocrinology Inotrope Contraction (grammar) Chemistry Myocyte Thapsigargin Angiotensin ii Contractility Calcium
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.
format	Articulo Articulo
author	Vila Petroff, Martín Gerardo Aiello, Ernesto Alejandro Palomeque, Julieta Salas, Margarita Ana Mattiazzi, Alicia Ramona
author_facet	Vila Petroff, Martín Gerardo Aiello, Ernesto Alejandro Palomeque, Julieta Salas, Margarita Ana Mattiazzi, Alicia Ramona
author_sort	Vila Petroff, Martín Gerardo
title	Subcellular mechanisms of the positive inotropic effect of angiotensin II in cat myocardium
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
publishDate	2000
url	http://sedici.unlp.edu.ar/handle/10915/127068
work_keys_str_mv	AT vilapetroffmartingerardo subcellularmechanismsofthepositiveinotropiceffectofangiotensiniiincatmyocardium AT aielloernestoalejandro subcellularmechanismsofthepositiveinotropiceffectofangiotensiniiincatmyocardium AT palomequejulieta subcellularmechanismsofthepositiveinotropiceffectofangiotensiniiincatmyocardium AT salasmargaritaana subcellularmechanismsofthepositiveinotropiceffectofangiotensiniiincatmyocardium AT mattiazzialiciaramona subcellularmechanismsofthepositiveinotropiceffectofangiotensiniiincatmyocardium
bdutipo_str	Repositorios
_version_	1764820451235725315

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

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