Alterations in cardiac parasympathetic function in aged rats

A. U. Ferrari, A. Daffonchio, S. Gerosa, G. Mancia

Research output: Contribution to journalArticlepeer-review


Aging impairs sympathetic and parasympathetic cardiac control. Although the reduced sympathetic responses are known to depend on an age-related cardiac β-adrenoceptor dysfunction, the hypothesis of a parallel cardiac muscarcinic receptor dysfunction underlying the reduced parasympathetic responses has never been tested. We therefore measured the bradycardiac responses to graded electrical stimulations of the right efferent vagus and to graded bolus intravenous injections of acetylcholine in anesthetized, vagotomized rats of young (16 wk) and old (103 wk) age. Unexpectedly, the bradycardia was markedly larger (> 2-fold) in old than in young rats with both the electrical and the pharmacological stimulus. This indicates that at variance with its effects on β-adrenergic receptor responsiveness, aging not only fails to impair but actually enhances cardiac muscarcinic receptor responsiveness. It also suggests the more general conclusion that aging has complex and diversified effects rather than simply and uniformly depressing biological functions.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number2 29-2
Publication statusPublished - 1991


  • Acetylcholine
  • Aging
  • Baroreceptor reflexes
  • Cardiac muscarinic receptors
  • Heart rate
  • Neural cardiovascular control

ASJC Scopus subject areas

  • Physiology


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