Neuropeptide Y and norepinephrine cooperatively inhibit human tracheal gland cell secretion

The effects of neuropeptide Y (NPY) and norepinephrine (NE) on the secretion of human tracheal gland (HTG) cells in culture were examined using the bronchial inhibitor (BrI) as a secretory marker. NPY by itself provoked no change in secretion, neither in intracellular Ca2+ nor in adenosine 3',5'-cyclic monophosphate (cAMP) levels. NE induced transient intracellular Ca2+ mobilization and an increase of intracellular cAMP and also, as previously described, a short-time concentration-dependent decrease of BrI secreted by HTG cells. When applied together on HTG cells, NPY and NE induced an increase of intracellular cAMP, a discrete sustained increase of basal intracellular Ca2+, and a long-lasting inhibition of secretion. Our data suggest that NPY acts for human tracheal gland cells as a NE neuromodulator rather than as a neurotransmitter. Thus culture of HTG cells appears to be an interesting pharmacological support for studying inhibition of bronchial secretion and could be applied in the study of pathologies where hypersecretion is observed, such as cystic fibrosis.