5-Hydroxytryptamine extraction by the lung.

Both 5-hydroxytryptamine and norepinephrine are removed from blood during a single passage through the pulmonary vasculature of the dog; 5-hydroxytryptamine is removed to a greater degree than is norepinephrine. The magnitude of extraction of both 5-hydroxytryptamine and norepinephrine is similar to that previously determined in man. In the intact dog, imipramine inhibits the uptake of 5-hydroxytryptamine by the lung in a dose-dependent manner.