MICROPIPET MEASUREMENT OF AIRWAY SUB-MUCOSAL GLAND SECRETION - AUTONOMIC EFFECTS

Abstract

A micropipette method for obtaining secretions from single submucosal gland ducts in vivo in cat tracheas is described. The secretory rate of 65 glands sampled under basal conditions in 16 animals varied from 3 to 30 nl/min (mean .+-. SE, 9.05 .+-. 0.60 nl/min) and varied 2- to 3-fold among glands sampled within an animal. Sequential samples collected from individual ducts during a 10-min period were highly repeatable (correlation coefficient, 0.96) and were remarkably constant for as long as 4 h. Vagal cooling decreased the secretory rate by a mean of 39% (n [number] = 11, P < 0.05). Stimulation of the cervical vagus nerves increased flow from 8.3 .+-. 0.7 to 16.4 .+-. 0.8 nl/min (n = 15, P < 0.01), an effect that was abolished by i.v. injection of 0.5 mg of atropine sulfate/kg of body weight or by cooling of the vagus nerves, but not by 0.08 mg of phentolamine/kg i.v. I.v. injection of 0.3 mg of phenylephrine/kg of body weight increased flow from 8.6 .+-. 0.6 to 18.9 .+-. 1.1 nl/min (n = 20, P < 0.001), an effect that was prevented by phentolamine, but not by atropine. Cholinergic and .alpha.-adrenergic stimulation increases fluid secretion from feline submucosal glands.