|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 202, Issue 24 3647-3658, Copyright © 1999 by Company of Biologists
JOURNAL ARTICLES |
AK Gamperl, WK Milsom, AP Farrell and T Wang
Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada. t.wang.1@bham.ac.uk
Central vascular blood flows and ventilation were measured in conscious toads (Bufo marinus) at 15 and 25 degrees C. The animals were exposed to hypoxia (Fi(O)(sum)=0.10 and 0.05, where Fi(O)(sum) is the fractional oxygen concentration of inspired air) at both temperatures. In addition, the cardiorespiratory responses to hypercapnia (Fi(CO)(sum)=0.05) and atropine injection (5 mg kg(-)(1); 7.4 &mgr;mol kg(-)(1)) were studied at 25 degrees C. At 25 degrees C, systemic blood flow ( q_dot (sys)) exceeded pulmocutaneous blood flow ( q_dot (pc)), indicating a large net right-to-left shunt ( q_dot (pc)/ q_dot (sys) was 0.39). q_dot (pc)/ q_dot (sys) was reduced significantly to 0.22 at 15 degrees C. At both temperatures, q_dot (pc) increased significantly during hypoxia (from 26.2 to 50.8 ml min(-)(1 )kg(-)(1) at 25 degrees C and from 11. 2 to 18.9 ml min(-)(1 )kg(-)(1) at 15 degrees C), whereas q_dot (sys) changed little (from 77.2 to 66.2 ml min(-)(1 )kg(-)(1) at 25 degrees C and from 54.3 to 50.1 ml min(-)(1 )kg(-)(1) at 15 degrees C). As a result, the net right-to-left shunt was greatly reduced, while total cardiac output remained almost unaffected. The ventilatory response was more pronounced during hypercapnia but, since q_dot (pc) and q_dot (sys) were affected similarly, there was no change in the shunt pattern. In undisturbed toads at 25 degrees C, atropine injection increased q_dot (pc) and eliminated the net right-to-left shunt. This is consistent with the known vagal innervation of the pulmonary artery.The present study shows that the cardiac right-to-left shunt that prevails in undisturbed and resting toads is reduced with increased temperature and during hypoxia. These findings are consistent with the general view that the cardiac right-to-left shunt is regulated and reduced whenever oxygen delivery is compromised or metabolic rate is increased.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  E. W. Taylor, D. V. Andrade, A. S. Abe, C. A. C. Leite, and T. Wang The unequal influences of the left and right vagi on the control of the heart and pulmonary artery in the rattlesnake, Crotalus durissus J. Exp. Biol., January 1, 2009; 212(1): 145 - 151. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. L. Jennings and J. A. Donald Neurally-derived nitric oxide regulates vascular tone in pulmonary and cutaneous arteries of the toad, Bufo marinus Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2008; 295(5): R1640 - R1646. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 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]
|
|
|
|
|
|
W. W. Burggren and T. Z. Vitalis The interplay of cutaneous water loss, gas exchange and blood flow in the toad, Bufo woodhousei: adaptations in a terrestrially adapted amphibian J. Exp. Biol., January 1, 2005; 208(1): 105 - 112. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Galli, E. W. Taylor, and T. Wang The cardiovascular responses of the freshwater turtle Trachemys scripta to warming and cooling J. Exp. Biol., April 1, 2004; 207(9): 1471 - 1478. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. B. Andersen, M. S. Hedrick, and T. Wang Cardiovascular responses to hypoxia and anaemia in the toad Bufo marinus J. Exp. Biol., March 1, 2003; 206(5): 857 - 865. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. McKean, G. Li, and K. Wei Cardiac effects of hypoxia in the neotenous tiger salamander Ambystoma tigrinum J. Exp. Biol., June 15, 2002; 205(12): 1725 - 1734. [Abstract] [Full Text] [PDF]
|
|
