The pharmacological modulation of [3H]-disaturated phosphatidylcholine overflow from perifused lung slices of adult rats: a new method for the study of lung surfactant secretion.

Lung slices from adult rats incubated in [methyl-3H]-choline chloride formed [3H]-disaturated phosphatidylcholine ( [3H]-DSPC) which was used as an index of lung surfactant. The slices were perifused after 3 h incubation in [methyl-3H]-choline chloride and the overflow of [3H]-DSPC, as a rate coefficient, was used as a measure of surfactant secretion. The basal overflow of [3H]-DSPC rapidly declined over the first 30 min of perifusion and then declined slowly. Salbutamol induced a prolonged, and sometimes delayed, increase in [3H]-DSPC overflow, which was reduced by (+/-)-propranolol. Potassium chloride produced an immediate, and usually transient, increase in [3H]-DSPC overflow which was not modified by atropine or (+/-)-propranolol. Adenosine 5'-triphosphate, but not phenylephrine, also increased [3H]-DSPC overflow. This method can measure the magnitude and time-course of lung surfactant secretion induced by drugs.