QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by SMATRESK, N. J. Articles by CAMERON, J. N. Search for Related Content PubMed Articles by SMATRESK, N. J. Articles by CAMERON, J. N. Social Bookmarking                         What's this?

Journal of Experimental Biology 96,263-280 (1982)
Published by Company of Biologists 1982

Respiration and Acid-Base Physiology of the Spotted Gar, A Bimodal Breather : I. Normal Values, and the Response to Severe Hypoxia

NEAL J. SMATRESK ¹ and J. N. CAMERON ²

¹ Departments of Zoology and Marine Studies, The University of Texas at Austin, Port Aransas Marine Laboratory, Port Aransas, Texas 78373, U.S.A.; University of Pennsylvania, School of Medicine, Department of Physiology Philadelphia, Penna. 19104, U.S.A.
² Departments of Zoology and Marine Studies, The University of Texas at Austin, Port Aransas Marine Laboratory, Port Aransas, Texas 78373, U.S.A.

In normally aerated water, at 20 °C, gar accounted for 42 % of their M_OO2 from their lungs, while in hypoxic water (P_OO2 12 torr) their entire M_OO2 was from the lung, and O₂ was lost through the gills. CO₂ excretion in both normoxia and hypoxia was primarily via the gills.

Lung ventilation increased 1150%, accompanied by an elevation of pulmonary perfusion from 5.9 to 12.1 ml.kg^-1.min^-1 in hypoxia, which accounts for the enhanced pulmonary M_OO2. Cardiac output increased from 31 to 40.5 ml.kg^-1.min^-1 and systemic perfusion was maintained in hypoxia.

The difference in acid-base status between pre- and post-branchial blood (P_COCO2, pH and total CO₂), changed only slightly during hypoxia, but the oxygen difference reversed. Normal dorsal aortic (DA) P_OO2 was 23.8 torr, ventral aortic (VA) 20.3; during aquatic hypoxia the mean values were 21.9 and 22.6, respectively. Blood pressure rose in both the VA and DA in hypoxia but the branchial vascular resistance did not change. The oxygen transfer factor did not change significantly between normoxia and hypoxia.

Anatomical studies of the gill microvasculature revealed a reduced and channelized lamellar circulation. No respiratory shunt pathways were found around the lamellae.

The physiological and anatomical data indicated that the gar did not change lamellar perfusion or use shunt pathways to avoid hypoxic O₂ loss.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				L. A. Alton, C. R. White, and R. S. Seymour Effect of aerial O2 partial pressure on bimodal gas exchange and air-breathing behaviour in Trichogaster leeri J. Exp. Biol., July 1, 2007; 210(13): 2311 - 2319. [Abstract] [Full Text] [PDF]

				A. P. Farrell Tribute to P. L. Lutz: a message from the heart - why hypoxic bradycardia in fishes? J. Exp. Biol., May 15, 2007; 210(10): 1715 - 1725. [Abstract] [Full Text] [PDF]

				S. L. Prassack, B. Bagatto, and R. P. Henry Effects of temperature and aquatic PO2 on the physiology and behaviour of Apalone ferox and Chrysemys picta J. Exp. Biol., March 8, 2002; 204(12): 2185 - 2195. [Abstract] [Full Text] [PDF]

				R. Wilson, M. Harris, J. Remmers, and S. Perry Evolution of air-breathing and central CO(2)/H(+) respiratory chemosensitivity: new insights from an old fish? J. Exp. Biol., January 11, 2000; 203(22): 3505 - 3512. [Abstract] [PDF]

				K. Prabha, D. Bernard, M Gardner, and N. Smatresk Ventilatory mechanics and the effects of water depth on breathing pattern in the aquatic caecilian Typhlonectes natans J. Exp. Biol., January 1, 2000; 203(2): 263 - 272. [Abstract] [PDF]