Which of the following was previously used to diagnose bronchial asthma
Methacholine normally acts on M2 receptor present on heart. "Methacholine challenge test" was used to diagnose bronchial asthma, where it can cause bronchoconstriction because of increased sensitivity of M3 receptors due to airway hyperreactivity.
Oxtremorine
Methacoline
Carbachol
Oxybutynin