Objective—To characterize the accuracy of an ultrafine
99m-technetium-labeled carbon dry aerosol for
use in assessment of regional ventilation in calves
with pulmonary dysfunction.
Animals—7 Belgian White and Blue calves.
Procedure—The ultrafine aerosol was assessed by
comparing deposition (D) images with ventilation (V)
images obtained by use of 81m-krypton (81mKr) gas via
D-to-V ratio (D:V) image analysis in calves during
spontaneous breathing (SB) and during experimentally
induced pulmonary dysfunction (ePD).
Results—Mismatching index (LrTot) calculated on the
D:V images revealed a good match (LrTot, 0.96 ± 0.01)
between D and V distribution patterns in calves during
SB. Calculation of the ultrafine aerosol penetration
index relative to 81mKr (PIRel) revealed preferential distribution
of the ultrafine aerosol in lung parenchyma
(PIRel, 1.13 ± 0.11). In ePD, heterogeneity in the D:V
distribution was observed (LrTot, 0.78 ± 0.10) as a
result of ultrafine aerosol particles impaction in airways
as indicated by PIRel (0.66 ± 0.16) and a proportion
of pixels more radioactive in D images, compared
with V images, that was located in the central part of
the lung (47.5 ± 7.7% in ePD vs 32.8 ± 5.7% in SB).
However, this central deposition did not prevent visual
examination of the entire ventilated lung.
Conclusions and Clinical Relevance—The ultrafine
aerosol appears suitable for use in examination of
ventilated parts of lungs of cattle, even those with
impaired pulmonary function. However, airway
impaction of ultrafine aerosol particles impedes the
quantification of regional ventilation in cattle with
abnormal lung function. (Am J Vet Res 2001;62:
Objective—To compare sensitivity of the impulse
oscillometry system (IOS) with that of the conventional
reference technique (CRT; ie, esophageal balloon
method) for pulmonary function testing in horses.
Animals—10 horses (4 healthy; 6 with recurrent airway
obstruction [heaves] in remission).
Procedure—Healthy horses (group-A horses) and
heaves-affected horses (group-B horses) were
housed in a controlled environment. At each step of a
methacholine bronchoprovocation test, threshold concentration
(TC2SD; results in a 2-fold increase in SD of
a value) and sensitivity index (SI) were determined for
respiratory tract system resistance (Rrs) and respiratory
tract system reactance (Xrs) at 5 to 20 Hz by use
of IOS and for total pulmonary resistance (RL) and
dynamic lung compliance (Cdyn), by use of CRT.
Results—Bronchoconstriction resulted in an increase
in Rrs at 5 Hz (R5Hz) and a decrease in Xrs at all frequencies.
Most sensitive parameters were Xrs at 5 Hz
(X5Hz), R5Hz, and R5Hz:R10Hz ratio; RL and the provocation
concentration of methacholine resulting in a 35%
decrease in dynamic compliance (PC35Cdyn) were significantly
less sensitive than these IOS parameters.
The TC2SD for Xrs at 5 and 10 Hz was significantly
lower in group-B horses, compared with group-A
horses. The lowest TC2SD was obtained for X5Hz in
group-B horses and R5Hz in group-A horses.
Conclusions and Clinical Relevance—In contrast to
CRT parameters, IOS parameters were significantly
more sensitive for testing pulmonary function. The IOS
provides a practical and noninvasive pulmonary function
test that may be useful in assessing subclinical
changes in horses. (Am J Vet Res 2003;64:1414–1420)
Objective—To culture equine myoblasts from muscle microbiopsy specimens, examine myoblast production of reactive oxygen species (ROS) in conditions of anoxia followed by reoxygenation, and assess the effects of horseradish peroxidase (HRP) and myeloperoxidase (MPO) on ROS production.
Animals—5 healthy horses (5 to 15 years old).
Procedures—Equine skeletal myoblast cultures were derived from 1 or 2 microbiopsy specimens obtained from a triceps brachii muscle of each horse. Cultured myoblasts were exposed to conditions of anoxia followed by reoxygenation or to conditions of normoxia (control cells). Cell production of ROS in the presence or absence of HRP or MPO was assessed by use of a gas chromatography method, after which cells were treated with a 3,3′-diaminobenzidine chromogen solution to detect peroxidase binding.
Results—Equine skeletal myoblasts were successfully cultured from microbiopsy specimens. In response to anoxia and reoxygenation, ROS production of myoblasts increased by 71%, compared with that of control cells. When experiments were performed in the presence of HRP or MPO, ROS production in myoblasts exposed to anoxia and reoxygenation was increased by 228% and 183%, respectively, compared with findings for control cells. Chromogen reaction revealed a close adherence of peroxidases to cells, even after several washes.
Conclusions and Clinical Relevance—Results indicated that equine skeletal myoblast cultures can be generated from muscle microbiopsy specimens. Anoxia-reoxygenationtreated myoblasts produced ROS, and production was enhanced in the presence of peroxidases. This experimental model could be used to study the damaging effect of exercise on muscles in athletic horses.