Diffusion of Gases from Alveolus to Precapillary Arteries

Abstract

A cardiac catheter with a platinum electrode just proximal to its tip, "wedged" in a branch of the pulmonary artery, was used to demonstrate the appearance of hydrogen or oxygen at the tip of the catheter after inhalation of these gases.

The Influence of Hydrogen Ion Concentration and Hypoxia on the Pulmonary Circulation*

“…The site of action remains unknown; it may be directly on the muscle cell or mediated by local receptors. Recent demonstrations that alveolar gas may diffuse through the walls of pulmonary precapillary vessels (40)(41)(42) emphasize the accessibility of these vessels to conditions in the surrounding pulmonary tissue. In patients where ventilation and perfusion are unevenly distributed, with consequent wide variations in the vascular environment, attention must henceforth be focused on the local blood and gas phases with which the vessel wall is in intimate contact in considering vasomotor reactivity.…”

Lung Circulation

“…It should be noted, however, that oxygen uptake has been proposed to also occur across the walls of larger arteries (118,297,586), a notion recently confirmed by elegant in vivo imaging techniques (611). While each small arteriole supplies a specific unit of respiratory tissue, the venules drain several portions of the lung.…”

The Influence of Hydrogen Ion in the Control of Pulmonary Artery Pressures in Patients with Obstructive Disease of the Lungs

“…It would appear, however, that the demon stration by Staub [1961] subsequently confirmed by Jameson [1963] and by Enson and Cournand [1963], that changing gas tensions in the alveoli are immediately discernible in pre-capillary vessels lends strong support to the notion that pre-capillary vessels of at least one mm in diameter may be responsible for the pressor response to hyp oxia [13][14][15]. Under these circumstances one need not invoke " re flexes" to explain the pressor response to alveolar hypoxia.…”