Transport and Binding of Lidocaine By Lung Slices and Perfused Lung of Rats

Abstract

The accumulation of radioisotopically labelled lidocaine was investigated in lung slices and perfused lungs of rats. Lidocaine was taken up by rat lung slices incubated in an oxygenated physiological solution (pH 7.4) at 37°. ¹⁴C-lidocaine accumulated in lung slices to a much greater extent than did ³H-sucrose, and the lidocaine space was approximately 7 times that of the extracellular space. No metabolism of lidocaine took place during the incubation period. The accumulation of lidocaine was inhibited by low temperature, while anaerobic conditions had no inhibitor effect. The uptake of lidocaine (0.028 mM) was slightly antagonized by high concentrations of Ca²⁺ (10 mM). The isolated perfused lung model was used for studying the pulmonary absorption of lidocaine from the vascular bed. Lidocaine was rapidly extracted from the perfusion solution and the drug appeared to accumulate in at least two compartments. It seems that in the rat lung a portion of the lidocaine taken up had accumulated within the cells, while som of it may be fixed to the cell surfaces.