|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 198, Issue 8 1783-1789, Copyright © 1995 by Company of Biologists
JOURNAL ARTICLES |
SR Hopkins, JW Hicks, TK Cooper and FL Powell
Department of Medicine, University of California, San Diego, La Jolla 92093-0623, USA.
During exercise, pulmonary gas exchange in reptiles was predicted to differ from that in mammals because of their less complex lung structure, which might reduce ventilation-perfusion heterogeneity (V/QL) at the expense of pulmonary diffusion limitation. To investigate this, the multiple inert gas elimination technique was used in six Varanus exanthematicus at rest and during maximal exercise. Trace amounts of six inert gases were infused into the external jugular vein and blood samples were collected from the pulmonary artery and the left atrium. Mixed expired gas samples and ventilatory and metabolic data were acquired. Indices of V/QL heterogeneity, calculated using a 50-compartment model, were low at rest (log standard deviation of perfusion distribution, logSDQ = 0.39) and increased significantly with exercise (logSDQ = 0.78). Oxygen diffusion limitation was apparent during exercise and was comparable to reported mammalian values. A molecular-mass-dependent limitation, suggesting limited intrapulmonary gas mixing, was evident only at rest. An increase in left atrial PO2 from 82mmHg at rest to 96 mmHg during exercise was associated with a corresponding decrease in PCO2. These data indicate adequacy of pulmonary ventilation and gas exchange for metabolic demands in exercising varanid lizards and suggest that less complex lung structures are not necessarily linked to increased pulmonary diffusion limitation.
This article has been cited by other articles:
|
|
 |
|
  F. L. Powell and S. R. Hopkins Comparative Physiology of Lung Complexity: Implications for Gas Exchange Physiology, April 1, 2004; 19(2): 55 - 60. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. M. Schmitt, F. L. Powell, and S. R. Hopkins Ventilation-perfusion inequality during normoxic and hypoxic exercise in the emu J Appl Physiol, December 1, 2002; 93(6): 1980 - 1986. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Overgaard and T. Wang Increased blood oxygen affinity during digestion in the snake Python molurus J. Exp. Biol., November 1, 2002; 205(21): 3327 - 3334. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Frappell, T. Schultz, and K. Christian Oxygen transfer during aerobic exercise in a varanid lizard Varanus mertensi is limited by the circulation J. Exp. Biol., September 1, 2002; 205(17): 2725 - 2736. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. F. Bennett and J. W. Hicks Postprandial exercise: prioritization or additivity of the metabolic responses? J. Exp. Biol., March 8, 2002; 204(12): 2127 - 2132. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Hicks, T Wang, and A. Bennett Patterns of cardiovascular and ventilatory response to elevated metabolic states in the lizard Varanus exanthematicus J. Exp. Biol., January 8, 2000; 203(16): 2437 - 2445. [Abstract] [PDF]
|
|
|
|
 |
|
 T. Owerkowicz, C. G. Farmer, J. W. Hicks, and E. L. Brainerd Contribution of Gular Pumping to Lung Ventilation in Monitor Lizards Science, June 4, 1999; 284(5420): 1661 - 1663. [Abstract] [Full Text]
|
|
|
|
|
|
S. R. Hopkins, W. M. Bayly, R. F. Slocombe, H. Wagner, and P. D. Wagner Effect of prolonged heavy exercise on pulmonary gas exchange in horses J Appl Physiol, May 1, 1998; 84(5): 1723 - 1730. [Abstract] [Full Text] [PDF]
|
|
