Labial glands from patients with cystic fibrosis (CF) were tested for a disease-related decrease in cholinergically-induced K release. Labial gland slices from normal controls and patients with cystic fibrosis were incubated in vitro in the presence or absence of cholinergic and adrenergic agonists and with or without a phosphodiesterase inhibitor. Both control and CF glands released K in response to cholinergic stimulation only; no K release response was detected to alpha- or beta- adrenergic stimulation. In contrast to previous results reported for parotid glands, no CF-related decrease in cholinergically-induced K release was detected. Both normal and CF glands released significantly less K with carbachol stimulation in the presence of the phosphodiesterase inhibitor. Overall, the results suggest considerable interglandular differences in disease sensitivity and functional regulation of K release.