Substance P as a factor enhancing resistance of the surfactant lung system to chronic immobilization stress

In chronic experiments on non-line white rats the influence of system (intraperitoneal) and central (into the lateral brain ventricle) administration of substance P on lung surfactant system was studied in stressed and non-stressed animals. A single injection of substance P limited pulmonary surfactant activity disorders in immobilisation stress. Stress-induced increase of phospholipids level in broncho-alveolar lavage fluid remained the same in intracerebroventricular administration and was partly reduced in intraperitoneal one. In intact rats, a single injection of peptide was accompanied by alveolar phospholipids accumulation. In rabbits, multiple intracerebroventricular injections of substance P enhanced the opposite effect.