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This Article Full Text Full Text (PDF) All Versions of this Article: 291/6/H2735    most recent 00522.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Koba, S. Articles by Li, J. Search for Related Content PubMed PubMed Citation Articles by Koba, S. Articles by Li, J.

Sympathetic responses to exercise in myocardial infarction rats: a role of central command

Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania

Submitted 22 May 2006 ; accepted in final form 9 July 2006

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.

congestive heart failure; mesencephalic locomotor region; renal sympathetic nerve activity; lumbar sympathetic nerve activity

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