Paradoxical effect of hypercapnia on toad heart muscle

Autores
Mattiazzi, Alicia Ramona; Cingolani, Horacio Eugenio
Año de publicación
1977
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Experiments were performed on strips dissected from toad ventricles driven at a constant frequency of 12 beats/min. After equilibration, the Pco2 of the medium was altered from 25 to 95 mm Hg or from 95 to 25 mm Hg. Developed tension (DT) and maximal rate of tension development (dT/dtmax) were recorded during a 30-minute period after the change in Pco2. In the first experimental series at 30°C, increasing Pco2, resulted in a decrease in DT and dT/dtmax, followed by a recovery of contractility that reached levels higher than controls. In the second and third series, performed after the addition to the bath of practolol (1 x 10-6M) or after reserpinization, high Pco2, depressed contractility but the recovery did not surpass control values after 30 minutes of hypercapnia. In this series, when high PcO2 was replaced by low Pco2 there was an increase in DT and dT/dtmax followed by a decrease that reached control levels within a 30-minute period. In the fourth series, at 22°C the significant decreases in DT and dT/dtmax observed after increasing Pco2 were followed by a recovery that surpassed control values. These results define the existence in toad cardiac muscle of a mechanism that tends to return contractility to control levels after a change in Pco2. Within 30 minutes this mechanism, present even after inhibition of catecholamine action, completely counteracts the primary negative inotropic effect of high Pco2 and the positive inotropic action of hypocapnia.
Facultad de Ciencias Médicas
Materia
Medicina
Ciencias Médicas
toad
hypocapnia
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:10915/131090

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network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Paradoxical effect of hypercapnia on toad heart muscleMattiazzi, Alicia RamonaCingolani, Horacio EugenioMedicinaCiencias MédicastoadhypocapniaExperiments were performed on strips dissected from toad ventricles driven at a constant frequency of 12 beats/min. After equilibration, the Pco2 of the medium was altered from 25 to 95 mm Hg or from 95 to 25 mm Hg. Developed tension (DT) and maximal rate of tension development (dT/dtmax) were recorded during a 30-minute period after the change in Pco2. In the first experimental series at 30°C, increasing Pco2, resulted in a decrease in DT and dT/dtmax, followed by a recovery of contractility that reached levels higher than controls. In the second and third series, performed after the addition to the bath of practolol (1 x 10-6M) or after reserpinization, high Pco2, depressed contractility but the recovery did not surpass control values after 30 minutes of hypercapnia. In this series, when high PcO2 was replaced by low Pco2 there was an increase in DT and dT/dtmax followed by a decrease that reached control levels within a 30-minute period. In the fourth series, at 22°C the significant decreases in DT and dT/dtmax observed after increasing Pco2 were followed by a recovery that surpassed control values. These results define the existence in toad cardiac muscle of a mechanism that tends to return contractility to control levels after a change in Pco2. Within 30 minutes this mechanism, present even after inhibition of catecholamine action, completely counteracts the primary negative inotropic effect of high Pco2 and the positive inotropic action of hypocapnia.Facultad de Ciencias Médicas1977info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf117-122http://sedici.unlp.edu.ar/handle/10915/131090enginfo:eu-repo/semantics/altIdentifier/issn/0009-7330info:eu-repo/semantics/altIdentifier/issn/1524-4571info:eu-repo/semantics/altIdentifier/doi/10.1161/01.res.41.1.117info:eu-repo/semantics/altIdentifier/pmid/405161info: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:UNLP2025-09-29T11:31:42Zoai:sedici.unlp.edu.ar:10915/131090Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:31:42.589SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Paradoxical effect of hypercapnia on toad heart muscle
title Paradoxical effect of hypercapnia on toad heart muscle
spellingShingle Paradoxical effect of hypercapnia on toad heart muscle
Mattiazzi, Alicia Ramona
Medicina
Ciencias Médicas
toad
hypocapnia
title_short Paradoxical effect of hypercapnia on toad heart muscle
title_full Paradoxical effect of hypercapnia on toad heart muscle
title_fullStr Paradoxical effect of hypercapnia on toad heart muscle
title_full_unstemmed Paradoxical effect of hypercapnia on toad heart muscle
title_sort Paradoxical effect of hypercapnia on toad heart muscle
dc.creator.none.fl_str_mv Mattiazzi, Alicia Ramona
Cingolani, Horacio Eugenio
author Mattiazzi, Alicia Ramona
author_facet Mattiazzi, Alicia Ramona
Cingolani, Horacio Eugenio
author_role author
author2 Cingolani, Horacio Eugenio
author2_role author
dc.subject.none.fl_str_mv Medicina
Ciencias Médicas
toad
hypocapnia
topic Medicina
Ciencias Médicas
toad
hypocapnia
dc.description.none.fl_txt_mv Experiments were performed on strips dissected from toad ventricles driven at a constant frequency of 12 beats/min. After equilibration, the Pco2 of the medium was altered from 25 to 95 mm Hg or from 95 to 25 mm Hg. Developed tension (DT) and maximal rate of tension development (dT/dtmax) were recorded during a 30-minute period after the change in Pco2. In the first experimental series at 30°C, increasing Pco2, resulted in a decrease in DT and dT/dtmax, followed by a recovery of contractility that reached levels higher than controls. In the second and third series, performed after the addition to the bath of practolol (1 x 10-6M) or after reserpinization, high Pco2, depressed contractility but the recovery did not surpass control values after 30 minutes of hypercapnia. In this series, when high PcO2 was replaced by low Pco2 there was an increase in DT and dT/dtmax followed by a decrease that reached control levels within a 30-minute period. In the fourth series, at 22°C the significant decreases in DT and dT/dtmax observed after increasing Pco2 were followed by a recovery that surpassed control values. These results define the existence in toad cardiac muscle of a mechanism that tends to return contractility to control levels after a change in Pco2. Within 30 minutes this mechanism, present even after inhibition of catecholamine action, completely counteracts the primary negative inotropic effect of high Pco2 and the positive inotropic action of hypocapnia.
Facultad de Ciencias Médicas
description Experiments were performed on strips dissected from toad ventricles driven at a constant frequency of 12 beats/min. After equilibration, the Pco2 of the medium was altered from 25 to 95 mm Hg or from 95 to 25 mm Hg. Developed tension (DT) and maximal rate of tension development (dT/dtmax) were recorded during a 30-minute period after the change in Pco2. In the first experimental series at 30°C, increasing Pco2, resulted in a decrease in DT and dT/dtmax, followed by a recovery of contractility that reached levels higher than controls. In the second and third series, performed after the addition to the bath of practolol (1 x 10-6M) or after reserpinization, high Pco2, depressed contractility but the recovery did not surpass control values after 30 minutes of hypercapnia. In this series, when high PcO2 was replaced by low Pco2 there was an increase in DT and dT/dtmax followed by a decrease that reached control levels within a 30-minute period. In the fourth series, at 22°C the significant decreases in DT and dT/dtmax observed after increasing Pco2 were followed by a recovery that surpassed control values. These results define the existence in toad cardiac muscle of a mechanism that tends to return contractility to control levels after a change in Pco2. Within 30 minutes this mechanism, present even after inhibition of catecholamine action, completely counteracts the primary negative inotropic effect of high Pco2 and the positive inotropic action of hypocapnia.
publishDate 1977
dc.date.none.fl_str_mv 1977
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
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info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/131090
url http://sedici.unlp.edu.ar/handle/10915/131090
dc.language.none.fl_str_mv eng
language eng
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info:eu-repo/semantics/altIdentifier/issn/1524-4571
info:eu-repo/semantics/altIdentifier/doi/10.1161/01.res.41.1.117
info:eu-repo/semantics/altIdentifier/pmid/405161
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)
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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
117-122
dc.source.none.fl_str_mv reponame:SEDICI (UNLP)
instname:Universidad Nacional de La Plata
instacron:UNLP
reponame_str SEDICI (UNLP)
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repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
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