Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect

Myocardial stretch produces an increase in developed force (DF) that occurs in two phases: the first (rapidly occurring) is generally attributed to an increase in myofilament calcium responsiveness and the second (gradually developing) to an increase in [Ca<sup>2+</sup>]<sub>i</...

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Autores principales: Álvarez, Bernardo Víctor, Pérez, Néstor Gustavo, Ennis, Irene Lucía, Camilión de Hurtado, María Cristina, Cingolani, Horacio Eugenio
Formato: Articulo
Lenguaje:Inglés
Publicado: 1999
Materias:
Medicina
myocardial stretch
Ca2+
transient
Anrep effect
pHi
Na+/Ca2+ exchanger
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/122777
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-122777
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Medicina
myocardial stretch
Ca2+
transient
Anrep effect
pHi
Na+/Ca2+ exchanger
spellingShingle Medicina
myocardial stretch
Ca2+
transient
Anrep effect
pHi
Na+/Ca2+ exchanger
Álvarez, Bernardo Víctor
Pérez, Néstor Gustavo
Ennis, Irene Lucía
Camilión de Hurtado, María Cristina
Cingolani, Horacio Eugenio
Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect
topic_facet Medicina
myocardial stretch
Ca2+
transient
Anrep effect
pHi
Na+/Ca2+ exchanger
description Myocardial stretch produces an increase in developed force (DF) that occurs in two phases: the first (rapidly occurring) is generally attributed to an increase in myofilament calcium responsiveness and the second (gradually developing) to an increase in [Ca<sup>2+</sup>]<sub>i</sub>. Rat ventricular trabeculae were stretched from ≈88% to ≈98% of L<sub>max</sub>, and the second force phase was analyzed. Intracellular pH, [Na⁺]<sub>i</sub>, and Ca<sup>2+</sup> transients were measured by epifluorescence with BCECF-AM, SBFI-AM, and fura-2, respectively. After stretch, DF increased by 1.94±0.2 g/mm² (P<0.01, n=4), with the second phase accounting for 28±2% of the total increase (P<0.001, n=4). During this phase, SBFI<sub>340/380</sub> ratio increased from 0.73±0.01 to 0.76±0.01 (P<0.05, n=5) with an estimated [Na⁺]<sub>i</sub> rise of ≈6 mmol/L. [Ca<sup>2+</sup>]<sub>i</sub> transient, expressed as fura-2<sub>340/380</sub> ratio, increased by 9.2±3.6% (P<0.05, n=5). The increase in [Na⁺]<sub>i</sub> was blocked by 5-(N-ethyl-N-isopropyl)-amiloride (EIPA). The second phase in force and the increases in [Na⁺]<sub>i</sub> and [Ca<sup>2+</sup>]<sub>i</sub> transient were blunted by AT₁ or ET<sub>A</sub> blockade. Our data indicate that the second force phase and the increase in [Ca<sup>2+</sup>]<sub>i</sub> transient after stretch result from activation of the Na⁺/H⁺ exchanger (NHE) increasing [Na⁺]<sub>i</sub> and leading to a secondary increase in [Ca<sup>2+</sup>]<sub>i</sub> transient. This reflects an autocrine-paracrine mechanism whereby stretch triggers the release of angiotensin II, which in turn releases endothelin and activates the NHE through ET<sub>A</sub> receptors.
format Articulo
Articulo
author Álvarez, Bernardo Víctor
Pérez, Néstor Gustavo
Ennis, Irene Lucía
Camilión de Hurtado, María Cristina
Cingolani, Horacio Eugenio
author_facet Álvarez, Bernardo Víctor
Pérez, Néstor Gustavo
Ennis, Irene Lucía
Camilión de Hurtado, María Cristina
Cingolani, Horacio Eugenio
author_sort Álvarez, Bernardo Víctor
title Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect
title_short Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect
title_full Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect
title_fullStr Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect
title_full_unstemmed Mechanisms Underlying the Increase in Force and Ca<sup>2+</sup> Transient That Follow Stretch of Cardiac Muscle : A Possible Explanation of the Anrep Effect
title_sort mechanisms underlying the increase in force and ca<sup>2+</sup> transient that follow stretch of cardiac muscle : a possible explanation of the anrep effect
publishDate 1999
url http://sedici.unlp.edu.ar/handle/10915/122777
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