Development of heart rate irregularities in chick embryos

Joachim Höchel, Ryuichi Akiyama, Takuya Masuko, James T. Pearson, Martin Nichelmann, Hiroshi Tazawa

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Heart rate (HR) irregularities in chick embryos were defined as large fluctuations (> 10 beats/min) comprising irregular, brief deceleration and/or acceleration of instantaneous HR (IHR). IHR was determined directly from the arterial blood pressure while adequate gas exchange was maintained through an eggshell and chorioallantoic membrane. Five embryos were examined on each day from day 11 to day 19 of incubation. Baseline HR was stable until day 12-13, and on around day 13-14 transient, rapid deceleration of HR (termed V pattern) began to appear, with a subsequent increase in its frequency and magnitude. The acceleration patterns (lambda, avian omega, and periodic patterns) appeared later, and the IHR became increasingly irregular, with additional, spontaneous deceleration and acceleration patterns toward hatching. Additional experiments with intravenous administration of autonomic drugs clearly showed that rapid deceleration of HR was mediated by parasympathetic nervous function but did not always show clear relations of sympathomimetic and sympathetic blocking agents to the acceleration patterns.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number2 44-2
Publication statusPublished - 5 Sep 1998
Externally publishedYes


  • Autonomic drugs
  • Blood pressure of allantoic artery
  • Deceleration and acceleration patterns
  • Heart rate fluctuations and variability
  • Instantaneous heart rate

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