Avian and Poultry Biology Reviews 16 (3), 2005
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Cardiac
Rhythms in Avian Embryos and Hatchlings
Hiroshi Tazawa
Department of Electrical and Electronic
Engineering, Muroran Institute of Technology, Muroran 050-8585,
ABSTRACT
Avian embryos develop within the confines of an eggshell independent
of maternal physiological functions. The eggshell provides not only an airway
for diffusive gas exchange of the embryo, but also a protective barrier between
the embryo and the surroundings. The wide space outside the eggshell is
available for measurements of embryonic physiological functions. Taking
advantage of the hard eggshell, severalmethods have been developed tomeasure
cardiogenic signalswhilemaintaining an adequate gas exchange through the
eggshell and cardiac rhythms of developing embryos have been determined.This
reviewintroduces the measuring methods for cardiogenic signals of embryos and
shows daily changes (developmental pattern) of some cardiovascular variables.
Daily determinations of heart rate (HR) from the cardiogenic signals exhibit
developmental patterns of mean HR (MHR) in embryos of various species of birds.
An allometric relationship is found between the fresh egg mass and
embryonicMHRin 34 species of birds investigated so far.The developmental
patterns ofMHR are also determined by continuous measurements of HR to
investigate a presence or absence of infradian, circadian and ultradian rhythms
in developing embryos and also hatchlings. For investigation into beat-to-beat
rhythms, instantaneous heart rate (IHR) is determined in prepipped and pipped
embryos and hatchlings. In chickens, IHR baseline begins to fluctuatewith
appearance of transient decelerations with subsequent accelerations during the
middle of incubation and distinctive patterns of IHR fluctuations develop in embryos
and hatchlings. The patterns and baseline of IHR respond to exposure to altered
environments and measurements of their responses have a possibility to
elucidate development of some physiological functions.
Keywords:
embryos, hatchlings, cardiogenic signals, mean heart rate, instantaneous heart
rate, developmental pattern, heart rate fluctuation
Use
of the Chicken as an Experimental Animal Model in Atherosclerosis
I. Ayalaa, B. Garcıa Perezb, G. Dome´necha, M.T. Castellsc and M. Valdesb
aDepartment
of Veterinary Medicine, College of Veterinary Medicine, University of Murcia,
Campus de Espinardo syn, Murcia 30100, SPAIN
bUniversitary
cDepartment of Cell Biology,
ABSTRACT
The
first evidence of experimental atherosclerosis was reported almost100 years
ago. In this review, research into spontaneous and induced atherosclerosis as
well as drug intervention studies in the experimental chicken model is discussed
together with trends for the future.The chicken is a good animal model for the
study of atherosclerosis research, since it presents lipoprotein levels similar
to those in humans. It is a biped, and develops spontaneous and induced
atherosclerosis mainly in response to high cholesterol diets (being stimulated
by hormones and vitamin D), vascular injury or infections (mainlyMarek’s
disease) in a similar way to how humans develop atherosclerosis. The chicken
atherosclerosis model proved itself useful and very suitable for in
vivo drug intervention studies. Emerging risk factors of this
potentially fatal disease (such as oxidative stress, inflammation or infection)
could be assessed with this model.
Keywords:
atherosclerosis, chicken, experimental animal model
Book
Reviews
Ducks,
Geese and Swans (Bird Families of the World)
The
Bowerbirds – Ptilonorhynchidae (Bird Families of the World)
The
Domestic Duck
The
New Encyclopedia of Birds