Effect of inhaled steroids on cholinergic transmission in human isolated bronchi.

Steroids have been found to facilitate cholinergic transmission in skeletal muscle, but possible effects in airways smooth muscles have not been studied. Therefore, choline acetyltransferase (CAT) activity, tissue content of stored acetylcholine and release of newly-synthesized [3H]acetylcholine were were measured in freshly-dissected human bronchi. All lung tissue was obtained from patients with lung cancer at thoracotomy. Group I bronchi were obtained from patients who also suffered from chronic obstructive bronchitis and had been treated for at least 6 weeks before surgery with daily doses of four puffs of flusinolid. Group II bronchi were obtained from patients who did not suffer from chronic obstructive airways disease and had not been treated with steroids. Neither CAT activity (3.1 nmol.h-1.mg protein-1) nor acetylcholine tissue content (260 pmol.100 mg-1), or electrically evoked [3H]acetylcholine release (about 2,000 dpm.100 mg-1) differed in the two groups. This cross sectional study indicates that inhaled steroids do not change cholinergic transmission beyond the level observed in the airways obtained from patients with lung cancer who do not suffer from chronic airways disease and have not been treated with inhaled steroids. This suggests that inhaled steroids can be given chronically without the induction of a facilitatory side-effect on cholinergic transmission within the airways.