Noninvasive assessment of alveolar microvascular recruitment in conscious non-sedated rats


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Yilmaz C., DANE D. M., RAVIKUMAR P., UNGER R. H., HSIA C. C. W.

RESPIRATORY PHYSIOLOGY & NEUROBIOLOGY, vol.190, no.1, pp.105-112, 2014 (SCI-Expanded) identifier identifier identifier

Abstract

Recruitment of alveolar microvascular reserves, assessed from the relationship between pulmonary diffusing capacity (DLCO) and perfusion ((Q)over dot(c)), is critical to the maintenance of arterial blood oxygenation. Leptin-resistant ZDF fatty diabetic (fa/fa) rats exhibit restricted cardiopulmonary physiology under anesthesia. To assess alveolar microvascular function in conscious, non-sedated, non-instrumented, and minimally restrained animals, we adapted a rebreathing technique to study fa/fa and control non-diabetic (+/+) rats (4-5 and 7-11 mo old) at rest and during mild spontaneous activity. Measurements included O-2 uptake, lung volume, (Q)over dot(c), DLCO, membrane diffusing capacity (DMCO), capillary blood volume (V-c) and septal tissue-blood volume. In older fa/fa than +/+ animals, DLCO and DMCO at a given (Q)over dot(c) were lower; V-c was reduced in proportion to (Q)over dot(c). Results demonstrate the consequences of alveolar microangiopathy in the metabolic syndrome: lung volume restriction, reduced (Q)over dot(c), and elevated membrane resistance to diffusion. At a given (Q)over dot(c), DLCO is lower in rats and guinea pigs than dogs or humans, consistent with limited alveolar microvascular reserves in small animals. Published by Elsevier B.V.