Comparison of mucus flow rate, radiolabelled glycoprotein output and smooth muscle contraction in the ferret trachea in vitro

1 The concentration‐response curves for rate of mucus output, labelled‐glycoprotein output and smooth muscle contraction in response to methacholine, phenylephrine and salbutamol were determined in the ferret trachea in vitro. 2 The potencies of methacholine and phenylephrine are both in order: smooth muscle contraction, glycoprotein output, rate of mucus output. 3 At lower concentrations methacholine is more potent than is phenylephrine on smooth muscle contraction, glycoprotein output and rate of mucus output. 4 Concentration‐response curves for salbutamol show very little change in rate of mucus output but a large increase in glycoprotein output. 5 It is concluded that the glycoprotein output induced by salbutamol may come from a source different from those induced by methacholine and phenylephrine.