Adrenergic secretory responses of submandibular tissues from control subjects and cystic fibrosis patients.

Adrenergic secretory responses of submandibular glands from control subjects and cystic fibrosis patients have been studied in vitro. In control tissues, isoproterenol (10 mumol/l) and noradrenaline (10 mumol/l) increased release of mucins and amylase to a similar extent (approximately 3-fold) and their actions were mediated by stimulation of beta-adrenergic receptors. In cystic fibrosis tissues, isoproterenol did not significantly increase release of mucins or amylase above the basal rate during 40 min incubation, whereas secretion in response to noradrenaline was not significantly different from that in control tissues. In the presence of a phosphodiesterase inhibitor, secretion of mucins and amylase in response to isoproterenol (10 mumol/l) in cystic fibrosis tissues was increased to the same level as that of noradrenaline (10 mumol/l); giving the same pattern of adrenergic responses in cystic fibrosis tissues as in control. The results suggest that overactivity of phosphodiesterase in cystic fibrosis cells might be the cause of the observed decreased secretion in response to a beta-adrenergic agonist.