Nervous influence on the pulmonary capacitance vessels in the rat.

Abstract

AbstractIt has previously been shown in experiments on rats that the pulmonary capacitance vessels play an important role as a blood depot in this species. In the present experiments one has attempted to evaluate the vasomotor nervous influence on this depot. Pulmonary blood volume was estimated from measurements of 128I‐tagged albumin and 51Cr‐tagged erythrocytes in the excised lungs of rats which had been rapidly frozen in liquid nitrogen. Partial pulmonary denervation was achieved beforehand in two groups of animals by cutting the left thoracic vago‐sympathetic nerve trunk. Animals from one of these groups were frozen without further treatment, whereas those from the other group were exposed to a standardized blood loss immediately before being immersed in liquid nitrogen. When compared to the situation in control animals the left lung from animals of both the above groups contained relatively more blood than did their right lung. Furthermore the total pulmonary blood volume was found to be increased in animals with such partly denervated lungs. The reduction in pulmonary blood volume observed subsequent to a blood loss, was less marked in animals where the left vago‐sympathetic nerve trunk had been cut than in animals with intact pulmonary innervation. It is concluded that the pulmonary blood volume in the rat is influenced through vasomotor nerves both when a blood loss has taken place and during normal circulatory conditions.