Cardiac activity during airway resistance alterations with intravenous and inhaled methacholine

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Measurement of airway contractile responses to methacholine (MCh) is an important investigational tool in humans and mice. However, i.v. administration of MCh in murine models may suffer from potential cardiac sequelae produced by stimulation of cholinergic receptors within cardiac muscle. Therefore, we studied the i.v. (0-10,000 μg/kg) and aerosolized (inhaled; 0-25 mg/ml) administration of MCh, to determine their effects on pulmonary resistance (RL) and cardiac muscle activity (as heart rate; HR) in anesthetized, mechanically-ventilated C57Bl6 mice. MCh, i.v., increased RL but produced: (1) prolonged asystole (29-47 sec); (2) subsequent overshoot of baseline HR; and (3) prolonged HR recovery times (7-25 min), suggestive of sympathetic modulation after cholinergic stimulation. In contrast, inhaled MCh aerosol produced no change in HR, while increasing RL similar to i.v. MCh. These results suggest that, for specific instances utilizing the plethysmographic technique, inhaled MCh aerosol may be superior to i.v. administration, due to the avoidance of potential bouts of asystole that can confound experimental results and lead to premature death of mice.

Original languageEnglish (US)
Pages (from-to)281-292
Number of pages12
JournalRespiratory Physiology and Neurobiology
Issue number3
StatePublished - Feb 25 2004
Externally publishedYes


  • Airway, resistance
  • Mammals, mouse
  • Mechanics of breathing, airway resistance
  • Muscle, cardiac
  • Pharmacological agents, methacholine
  • Techniques, plethysmography

ASJC Scopus subject areas

  • General Neuroscience
  • Physiology
  • Pulmonary and Respiratory Medicine


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