Effect of Substance P on Pulmonary Resistance and Dynamic Pulmonary Compliance in the Anaesthetized Cat and Guinea‐pig

Abstract

The effect of substance P, acetylcholine, and histamine on pulmonary resistance (R_L) and on pulmonary dynamic compliance (C_DYN) was studied in the anaesthetized cat and guinea-pig. In the anaesthetized guinea-pig, substance P (0.1-1.0 üg/kg), acetylcholine (1.0-10 μg/kg), and histamine (1.0-10.0 μg/kg) produced a dose-dependent increase in R_L and decrease in C_DYN. In the anaesthetized cat, the effect of substance P was weak on both R_L and C_DYN, whereas histamine (5-50 μg/kg) produced a dose-dependent increase in C_DYN, but the effect on R_L was weak. The effect of acetylcholine was qualitatively the same as in the anaesthetized guina-pig but about 10 times less effective.