|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Maturation of cardiovascular control mechanisms in the embryonic emu (Dromiceius novaehollandiae)
1 Department of Ecology and Evolutionary Biology, University of California,
Irvine, CA 92697, USA
2 Department of Biology, University of Akron, OH 44325, USA
3 Department of Biological Sciences, University of North Texas, Denton, TX
76203, USA
* Author for correspondence (e-mail: dcrossle{at}uci.edu)
Accepted 1 May 2003
Our understanding of avian embryonic cardiovascular regulation has been
based on studies in chickens. The present study was undertaken to determine if
the patterns established in chickens are generally applicable to the emu, a
ratite bird species. We studied cardiovascular physiology over the interval
from 60% to 90% of the emu's 50-day incubation period. During this period,
embryonic emus exhibit a slight fall in resting heart rate (from 171 beats
min-1 to 154 beats min-1) and a doubling of mean
arterial pressure (from 1.2 kPa to 2.6 kPa). Exposures to 15% or 10%
O2 initially decreased heart rate during the first period of emu
incubation studied [60% of incubation (60%I)] but increased heart rate in the
90%I group. Arterial pressure responded to hypoxia with an initial depression
(-1.6 kPa) at 60%I and 70%I but showed no response during the later periods of
incubation (80%I and 90%I). In addition, tonic stimulation of both cholinergic
and adrenergic (
and ß) receptors was present on heart rate at
70%I, with the cholinergic and ß-adrenergic tone increasing in strength
by 90%I. Arterial pressure was dependent on a constant ß-adrenergic and
constant -adrenergic tone from 60%I to 90%I. A comparison with
embryonic white leghorn chickens over a similar window of incubation revealed
that emus and white leghorn chickens both possess an adrenergic tone on heart
rate and pressure but that only emus possess a cholinergic tone on heart rate.
Collectively, these data indicate that the maturation of cardiovascular
control systems differs between white leghorn chickens and emus, inviting
investigation of additional avian species to determine other patterns.
Key words: cardiovascular regulation, embryogenesis, physiology, incubation period, cholinergic tone, adrenergic tone, emu, Dromiceius novaehollandiae
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  T. Owerkowicz, R. M. Elsey, and J. W. Hicks Atmospheric oxygen level affects growth trajectory, cardiopulmonary allometry and metabolic rate in the American alligator (Alligator mississippiensis) J. Exp. Biol., May 1, 2009; 212(9): 1237 - 1247. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Khorrami, H. Tazawa, and W. Burggren `Blood-doping' effects on hematocrit regulation and oxygen consumption in late-stage chicken embryos (Gallus gallus) J. Exp. Biol., March 15, 2008; 211(6): 883 - 889. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Burggren, S. Khorrami, A. Pinder, and T. Sun Body, eye, and chorioallantoic vessel growth are not dependent on cardiac output level in day 3-4 chicken embryos Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2004; 287(6): R1399 - R1406. [Abstract] [Full Text] [PDF]
|
|
