Sympathetic responses to exercise in myocardial infarction rats

A role of central command

Satoshi Koba, Zhaohui Gao, Jihong Xing, Lawrence Sinoway, Jianhua Li

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

In congestive heart failure (CHF), exaggerated sympathetic activation is observed during exercise, which elicits excess peripheral vasoconstriction. The mechanisms causing this abnormality are not fully understood. Central command is a central neural process that induces parallel activation of motor and cardiovascular systems. This study was undertaken to determine whether central command serves as a mechanism that contributes to the exaggerated sympathetic response to exercise in CHF. In decerebrated rats, renal and lumbar sympathetic nerve responses (RSNA and LSNA, respectively) to 30 s of fictive locomotion were examined. The fictive locomotion was induced by electrical stimulation of the mesencephalic locomotor region (MLR). The study was performed in control animals (fractional shortening > 40%) and animals with myocardial infarctions (MI; fractional shortening < 30%). With low stimulation of the MLR (current intensity = 20 μA), the sympathetic responses were not significantly different in the control (RSNA: +18 ± 4%; LSNA: +3 ± 2%) and MI rats (RSNA: +16 ± 5%; LSNA: +8 ± 3%). With intense stimulation of the MLR (50 μA), the responses were significantly greater in MI rats (RSNA: +127 ± 15%; LSNA: +57 ± 10%) than in the control rats (RSNA: +62 ± 5%; LSNA: +21 ± 6%). In this study, the data demonstrate that RSNA and LSNA responses to intense stimulation of the MLR are exaggerated in MI rats. We suggest that intense activation of central command may play a role in evoking exaggerated sympathetic activation and inducing excessive peripheral vasoconstriction during exercise in CHF.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume291
Issue number6
DOIs
StatePublished - Dec 18 2006

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Myocardial Infarction
Heart Failure
Locomotion
Vasoconstriction
Cardiovascular System
Electric Stimulation
Kidney

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

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title = "Sympathetic responses to exercise in myocardial infarction rats: A role of central command",
abstract = "In congestive heart failure (CHF), exaggerated sympathetic activation is observed during exercise, which elicits excess peripheral vasoconstriction. The mechanisms causing this abnormality are not fully understood. Central command is a central neural process that induces parallel activation of motor and cardiovascular systems. This study was undertaken to determine whether central command serves as a mechanism that contributes to the exaggerated sympathetic response to exercise in CHF. In decerebrated rats, renal and lumbar sympathetic nerve responses (RSNA and LSNA, respectively) to 30 s of fictive locomotion were examined. The fictive locomotion was induced by electrical stimulation of the mesencephalic locomotor region (MLR). The study was performed in control animals (fractional shortening > 40{\%}) and animals with myocardial infarctions (MI; fractional shortening < 30{\%}). With low stimulation of the MLR (current intensity = 20 μA), the sympathetic responses were not significantly different in the control (RSNA: +18 ± 4{\%}; LSNA: +3 ± 2{\%}) and MI rats (RSNA: +16 ± 5{\%}; LSNA: +8 ± 3{\%}). With intense stimulation of the MLR (50 μA), the responses were significantly greater in MI rats (RSNA: +127 ± 15{\%}; LSNA: +57 ± 10{\%}) than in the control rats (RSNA: +62 ± 5{\%}; LSNA: +21 ± 6{\%}). In this study, the data demonstrate that RSNA and LSNA responses to intense stimulation of the MLR are exaggerated in MI rats. We suggest that intense activation of central command may play a role in evoking exaggerated sympathetic activation and inducing excessive peripheral vasoconstriction during exercise in CHF.",
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T2 - A role of central command

AU - Koba, Satoshi

AU - Gao, Zhaohui

AU - Xing, Jihong

AU - Sinoway, Lawrence

AU - Li, Jianhua

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N2 - In congestive heart failure (CHF), exaggerated sympathetic activation is observed during exercise, which elicits excess peripheral vasoconstriction. The mechanisms causing this abnormality are not fully understood. Central command is a central neural process that induces parallel activation of motor and cardiovascular systems. This study was undertaken to determine whether central command serves as a mechanism that contributes to the exaggerated sympathetic response to exercise in CHF. In decerebrated rats, renal and lumbar sympathetic nerve responses (RSNA and LSNA, respectively) to 30 s of fictive locomotion were examined. The fictive locomotion was induced by electrical stimulation of the mesencephalic locomotor region (MLR). The study was performed in control animals (fractional shortening > 40%) and animals with myocardial infarctions (MI; fractional shortening < 30%). With low stimulation of the MLR (current intensity = 20 μA), the sympathetic responses were not significantly different in the control (RSNA: +18 ± 4%; LSNA: +3 ± 2%) and MI rats (RSNA: +16 ± 5%; LSNA: +8 ± 3%). With intense stimulation of the MLR (50 μA), the responses were significantly greater in MI rats (RSNA: +127 ± 15%; LSNA: +57 ± 10%) than in the control rats (RSNA: +62 ± 5%; LSNA: +21 ± 6%). In this study, the data demonstrate that RSNA and LSNA responses to intense stimulation of the MLR are exaggerated in MI rats. We suggest that intense activation of central command may play a role in evoking exaggerated sympathetic activation and inducing excessive peripheral vasoconstriction during exercise in CHF.

AB - In congestive heart failure (CHF), exaggerated sympathetic activation is observed during exercise, which elicits excess peripheral vasoconstriction. The mechanisms causing this abnormality are not fully understood. Central command is a central neural process that induces parallel activation of motor and cardiovascular systems. This study was undertaken to determine whether central command serves as a mechanism that contributes to the exaggerated sympathetic response to exercise in CHF. In decerebrated rats, renal and lumbar sympathetic nerve responses (RSNA and LSNA, respectively) to 30 s of fictive locomotion were examined. The fictive locomotion was induced by electrical stimulation of the mesencephalic locomotor region (MLR). The study was performed in control animals (fractional shortening > 40%) and animals with myocardial infarctions (MI; fractional shortening < 30%). With low stimulation of the MLR (current intensity = 20 μA), the sympathetic responses were not significantly different in the control (RSNA: +18 ± 4%; LSNA: +3 ± 2%) and MI rats (RSNA: +16 ± 5%; LSNA: +8 ± 3%). With intense stimulation of the MLR (50 μA), the responses were significantly greater in MI rats (RSNA: +127 ± 15%; LSNA: +57 ± 10%) than in the control rats (RSNA: +62 ± 5%; LSNA: +21 ± 6%). In this study, the data demonstrate that RSNA and LSNA responses to intense stimulation of the MLR are exaggerated in MI rats. We suggest that intense activation of central command may play a role in evoking exaggerated sympathetic activation and inducing excessive peripheral vasoconstriction during exercise in CHF.

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