<原著>局在性アノキシアに対する肺血管反応の研究

Abstract

Since Euler and Liljestrand reported their studies on pulmonary vascular response to hypoxia, extensive research has been done on this problem for the purpose of elucidating both the regulatory mechanism of pulmonary circulation and the pathogenesis of cor pulmonale. Nevertheless complete agreement has not yet been reached on the pulmonary vascular response to hypoxia. In Chapter 1, we report patho-physiologic studies on the pulmonary vascular response to regional hypoxia and morphological observations of this response with the use of a rapid freezing method with liquid nitrogen in guinea pigs and rabbits. In Chapter 2, we describe the mechanism of pulmonary vascular response. The following conclusions were drawn from these experiments : 1) No significant change in P. A. pressure was observed in unilateral regional hypoxia which did not result in general hypoxemia. 2) Marked vasoconstriction and perivascular edema were seen in peripheral muscular arteries in guinea pig bronchioles with diameters of 150-300μ. No morphological changes were observed in pulmonary capillaries or veins. The muscular arterial response observed in guinea pigs was not demonstrated in rabbits. 3) Although the pattern of response of pulmonary arteries to regional hypoxia differs from species to species, it is most likely that morphological changes in peripheral muscular arteries are responsible for the increase of pulmonary vascular resistance induced by hypoxia. 4) Although pulmonary vascular constriction induced by hypoxia is considered to be due to the direct action of hypoxia itself on the vascular wall, a reflex mediated through an Axon reflex or autonomic nerve cannot be completely excluded.