From:
Sukie Crandall
Date: 2008-04-20 23:19:56 UTC
Subject: [ferrethealth] Abstracts
To: fhl <ferrethealth@yahoogroups.com>, ferret-l@LISTSERV.FERRETMAILINGLIST.ORG
Can J Physiol Pharmacol. 2008 January/February;86(1-2):46-54.
Adenosine reduces the reverse mode of the Na+/Ca2+ exchanger in ferret
cardiac fibres.
Hleihel W, Lafoux A, Ouaini N, Huchet-Cadiou C.
Faculte de Medecine, Universite Saint-Esprit de Kaslik, B.P. 446
Jounieh, Liban, Lebanon.
The aim of this study was to investigate the effects of adenosine on
reverse mode Na+/Ca2+ exchange. In intact ferret cardiac trabeculae, Na
+-free contractures were investigated after treating preparations with
ryanodine, a sarcoplasmic reticulum Ca2+-channel inhibitor, and
thapsigargin, a sarcoplasmic reticulum Ca2+-pump inhibitor added to
suppress the sarcoplasmic reticulum function. The effects of adenosine
(50-100 nmol/L), adenosine deaminase (ADA, 0.1-0.5 U/L), the A1 and
A2A receptor agonists CCPA (3-100 nmol/L) and CGS 21680 (25-100 nmol/
L), and the A1 and A2A receptor antagonists DPCPX (25 nmol/L) and ZM
241385 (25 nmol/L) were tested on Na+-free contractures. The
application of adenosine (50-100 nmol/L) had no significant effect on
the characteristics of the Na+-free contractures. However, the results
show that treatment with ADA (0.3 U/L), adenosine (>=50 nmol/L) and
CCPA, a specific A1 receptor agonist (3-100 nmol/L), all reduced the Na
+-free contracture amplitude. In the presence of ADA, the effects of
adenosine and CCPA were also reduced by a specific antagonist of A1
receptors (DPCPX, 25 nmol/L). Furthermore, adenosine, ADA, and CCPA
did not affect the properties of the contractile apparatus in Triton-
skinned fibres. It is therefore proposed that endogenous adenosine
reduced the reverse mode of the Na+/Ca2+ exchanger by acting on A1
receptors present in the sarcolemmal membrane.
full article:
https://article.pubs.nrc-cnrc.gc.ca:443/RPAS/RPViewDoc?issn=0008-4212&volume=86&issue=1-2&startPage=46&secure=true
Masui. 2008 Apr;57(4):408-19
Novel assessment of intracellular calcium transient decay in cardiac
muscle by curve-fitting with half-logistic function
[Article in Japanese]
Mizuno J, Arita H, Hanaoka K, Kusakari Y, Kurihara S.
Department of Anesthesiology, Teikyo University School of Medicine,
Tokyo 173-8605.
A decrease in intracellular calcium (Ca2+) concentration in the
cardiac muscle is one of the important factors to induce myocardial
relaxation. A mono-exponential (m-E) function has been used for
assessing myocardial relaxation curve of isometric tension and
intracellular calcium transient (CaT) decay, and the m-E time
constants for the relaxation curve of isometric tension (F tau E) and
CaT decay (Ca tau E) have been recognised as lusitropic indices.
However, we found that a half-logistic (h-L) function fits the
relaxation curve of isometric tension much more precisely than the
conventional m-E function in the ferret right ventricular (RV)
papillary muscle. Moreover, we demonstrated that the goodness of the h-
L fits for CaT decays was superior to the goodness of the m-E fits in
the rabbit RV and murine left ventricular papillary muscles. The
changes in the h-L time constants for the relaxation curves of
isometric tension (F tau L) and CaT decays (Ca tau L) with the
different onsets were significantly smaller than the changes in F tau
E and Ca tau E, respectively. The differences in the h-L non-zero
asymptotes for the relaxation curves of isometric tension and CaT
decays with the different onsets were smaller than the changes in the
m-E non-zero asymptotes. The h-L function model characterises the
amplitudes and time courses of the relaxation curve of isometric
tension and CaT decay more precisely than the m-E function model, and
thus F tau L and Ca tau L serve as more novel and reliable lusitropic
indices. Simultaneous analysis of myocardial relaxation curve of
isometric tension and CaT decay using h-L functions can become a
useful method for assessment of myocardial calcium handling.
Brain Res. 2008 Mar 10 [Epub ahead of print]
Visual-auditory spatial processing in auditory cortical neurons.
Bizley JK, King AJ.
Department of Physiology, Anatomy and Genetics, University of Oxford,
Parks Road, Oxford, OX1 3PT, UK.
Neurons responsive to visual stimulation have now been described in
the auditory cortex of various species, but their functions are
largely unknown. Here we investigate the auditory and visual spatial
sensitivity of neurons recorded in 5 different primary and non-primary
auditory cortical areas of the ferret. We quantified the spatial
tuning of neurons by measuring the responses to stimuli presented
across a range of azimuthal positions and calculating the mutual
information (MI) between the neural responses and the location of the
stimuli that elicited them. MI estimates of spatial tuning were
calculated for unisensory visual, unisensory auditory and for
spatially and temporally coincident auditory-visual stimulation. The
majority of visually responsive units conveyed significant information
about light-source location, whereas, over a corresponding region of
space, acoustically responsive units generally transmitted less
information about sound-source location. Spatial sensitivity for
visual, auditory and bisensory stimulation was highest in the anterior
dorsal field, the auditory area previously shown to be innervated by a
region of extrastriate visual cortex thought to be concerned primarily
with spatial processing, whereas the posterior pseudosylvian field and
posterior suprasylvian field, whose principal visual input arises from
cortical areas that appear to be part of the 'what' processing stream,
conveyed less information about stimulus location. In some neurons,
pairing visual and auditory stimuli led to an increase in the spatial
information available relative to the most effective unisensory
stimulus, whereas, in a smaller subpopulation, combined stimulation
decreased the spatial MI. These data suggest that visual inputs to
auditory cortex can enhance spatial processing in the presence of
multisensory cues and could therefore potentially underlie visual
influences on auditory localization.
Now, here is another article I am just drooling to get my hands on
since it could save ferrets:
Vet Clin North Am Exot Anim Pract. 2008 May;11(2):301-314.
Toxicology of Ferrets.
Dunayer E.
American Society for the Prevention of Cruelty to Animals (ASPCA)
Animal Poison Control Center (APCC), 1717 S. Philo Road, Suite 36,
Urbana, IL 61802, USA; College of Veterinary Medicine, University of
Illinois, 2001 S. Lincoln Avenue, Urbana, IL 61802, USA.
Because of their curious nature and small size, ferrets are at risk
for various toxicoses. At present, there is not a great deal of
information on specific toxicants in ferrets. This article initially
reviews general consideration in treating poisoning in ferrets, such
as obtaining history and decontamination. It then discusses some
specific agents that appear to be common causes of poisoning in
ferrets based on the experience of the ASPCA Animal Poison Control
Center.
[Non-text portions of this message have been removed]
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