Previous work indicates that one consequence of the accumulation of several xenobiotics in the lung is compromised pulmonary disposition of 5-hydroxytryptamine (5-HT). In the present studies, we examined whether pulmonary accumulation of chlorpromazine (CPZ), propranolol (P), imipramine (IMP), and clomipramine (Cl-IMP) affected 5-HT disposition in rabbit lungs. Pulmonary ecxtraction and metabolism of [14C]-5-HT during single pulmonary passage were examined using the reference indicator radioisotope dilution technique in male New Zealand albino rabbits. After control experiment, animals received CPZ or P (2.5, 5, or 10 mg/kg), IMP or Cl-IMP (0.25, 0.5 or 1.0 mg/kg) via the jugular vein. Pulmonary clearance was 83% of administered 5-HT. A significant proportion (28%) of total radioactivity in the bloodstream after single passage was recovered as 5-HIAA in control experiments. These values were reduced significantly to 70 and 20%, respectively upon prior administration of IMP (0.25 mg/kg). Cl-IMP was more effective in reducing these values further. CPZ and P were marginally effective at the highest dose. While prior administration of IMP and Cl-IMP resulted in pulmonary accumulation of both drugs, the latter accumulated to a significantly greater extent. These results suggest that Cl-IMP has higher affinity to the rabbit lung than IMP and may inhibit pulmonary uptake of 5-HT by competition for uptake and binding sites more than IMP.

Keywords:
Chlorphentermine, Chlorpromazine, Clomipramine, Imipramine, Propranolol, Pulmonary clearance of 5-HT, Pneumophilic drugs
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© 1983 S. Karger AG, Basel
1983
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