In:
Journal of Applied Physiology, American Physiological Society, Vol. 101, No. 1 ( 2006-07), p. 289-297
Abstract:
The spleen acts as an erythrocyte reservoir in highly aerobic species such as the dog and horse. Sympathetic-mediated splenic contraction during exercise reversibly enhances convective O 2 transport by increasing hematocrit, blood volume, and O 2 -carrying capacity. Based on theoretical interactions between erythrocytes and capillary membrane (Hsia CCW, Johnson RL Jr, and Shah D. J Appl Physiol 86: 1460–1467, 1999) and experimental findings in horses of a postsplenectomy reduction in peripheral O 2 -diffusing capacity (Wagner PD, Erickson BK, Kubo K, Hiraga A, Kai M, Yamaya Y, Richardson R, and Seaman J. Equine Vet J 18, Suppl: 82–89, 1995), we hypothesized that splenic contraction also augments diffusive O 2 transport in the lung. Therefore, we have measured lung diffusing capacity (Dl CO ) and its components during exercise by a rebreathing technique in six adult foxhounds before and after splenectomy. Splenectomy eliminated exercise-induced polycythemia, associated with a 30% reduction in maximal O 2 uptake. At any given pulmonary blood flow, Dl CO was significantly lower after splenectomy owing to a lower membrane diffusing capacity, whereas pulmonary capillary blood volume changed variably; microvascular recruitment, indicated by the slope of the increase in Dl CO with respect to pulmonary blood flow, was also reduced. We conclude that splenic contraction enhances both convective and diffusive O 2 transport and provides another compensatory mechanism for maintaining alveolar O 2 transport in the presence of restrictive lung disease or ambient hypoxia.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/japplphysiol.01600.2005
Language:
English
Publisher:
American Physiological Society
Publication Date:
2006
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
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