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 BURGGREN, W. Articles by JOHANSEN, K. Search for Related Content PubMed Articles by BURGGREN, W. Articles by JOHANSEN, K.

Journal of Experimental Biology 96,343-354 (1982)
Published by Company of Biologists 1982

Ventricular Haemodynamics in the Monitor Lizard Varanus Exanthematicus: Pulmonary and Systemic Pressure Separation

WARREN BURGGREN ¹ and KJELL JOHANSEN ²

¹ Department of Zoloogy, University of Massachusetts, Amherst, MA 01003-0027
² Department of Zoophysiology, University of Aarhus, DK-8000, Aarhus C., Denmark

The haemodynamics of the anatomically undivided ventricle of the monitor lizard Varanus exanthematicus have been examined by measurements of blood pressure and flow. Central blood P_OO2, P_COCO2 and pH were also measured.

Intracardiac pressure measurements show the ventricle to be functionally divided throughout systole into a high pressure pump (cavum arteriosum: ‘mean’ pressure 89 cm H₂O) perfusing the systemic circulation, and a low pressure pump (cavum pulmonale: ‘mean’ pressure 40 cm H₂O) perfusing the pulmonary circulation. Hypoxia produced by asphyxia or N₂ breathing changed systolic pressures in the ventricular cava, but never resulted in superimposable pressure waveforms which would have indicated a breakdown from ventricular division into two pressure pumps. Diastolic pressures were superimposable in the ventricular cava under all conditions.

Analysis of blood P_OO2 and O₂ content revealed the potential for nearly complete separation of left and right atrial blood in the ventricle, but both left-to-right and right-to-left shunts of considerable magnitude could also develop.

The varanid heart with its systolic pressure separation allows the development of high blood pressure gradients capable of driving a large cardiac output through the high impedance systemic vascular beds. Concurrently, the low impedance pulmonary circuit is perfused at a much reduced blood pressure, circumventing filtration of plasma into the lungs and impairment of gas exchange. Haemodynamically this situation resembles that present in crocodilians and the homeothermic vertebrates.

This article has been cited by other articles:

				J. S. Torday, V. K. Rehan, J. W. Hicks, T. Wang, J. Maina, E. R. Weibel, C. C.W. Hsia, R. J. Sommer, and S. F. Perry Deconvoluting lung evolution: from phenotypes to gene regulatory networks Integr. Comp. Biol., October 1, 2007; 47(4): 601 - 609. [Abstract] [Full Text] [PDF]

				G. L. J. Galli, H. Gesser, E. W. Taylor, H. A. Shiels, and T. Wang The role of the sarcoplasmic reticulum in the generation of high heart rates and blood pressures in reptiles J. Exp. Biol., May 15, 2006; 209(10): 1956 - 1963. [Abstract] [Full Text] [PDF]

				N. Skovgaard, A. S. Abe, D. V. Andrade, and T. Wang Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2005; 289(5): R1280 - R1288. [Abstract] [Full Text] [PDF]

				T. Wang, J. Altimiras, W. Klein, and M. Axelsson Ventricular haemodynamics in Python molurus: separation of pulmonary and systemic pressures J. Exp. Biol., December 1, 2003; 206(23): 4241 - 4245. [Abstract] [Full Text] [PDF]

				J. B. West Thoughts on the pulmonary blood-gas barrier Am J Physiol Lung Cell Mol Physiol, September 1, 2003; 285(3): L501 - L513. [Abstract] [Full Text] [PDF]

				T. Wang, J. Altimiras, and M. Axelsson Intracardiac flow separation in an in situ perfused heart from Burmese python Python molurus J. Exp. Biol., September 1, 2002; 205(17): 2715 - 2723. [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]