Use of the impulse oscillometry system for testing pulmonary function during methacholine bronchoprovocation in horses.

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 (TC(2SD); results in a 2-fold increase in SD of a value) and sensitivity index (SI) were determined for respiratory tract system resistance (R(rs)) and respiratory tract system reactance (X(rs)) at 5 to 20 Hz by use of IOS and for total pulmonary resistance (RL) and dynamic lung compliance (C(dyn)), by use of CRT. RESULTS: Bronchoconstriction resulted in an increase in R(rs) at 5 Hz (R(5Hz)) and a decrease in X(rs) at all frequencies. Most sensitive parameters were X(rs) at 5 Hz (X(5Hz)), R(5Hz), and R(5Hz):R(10Hz) ratio; RL and the provocation concentration of methacholine resulting in a 35% decrease in dynamic compliance (PC(35)C(dyn)) were significantly less sensitive than these IOS parameters. The TC(2SD) for X(rs) at 5 and 10 Hz was significantly lower in group-B horses, compared with group-A horses. The lowest TC(2SD) was obtained for X(5Hz) in group-B horses and R(5Hz) 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

Comparison of deposition images obtained by use of an ultrafine 99m-technetium-labeled carbon dry aerosol with ventilation images obtained by use of 81m-krypton gas for evaluation of pulmonary dysfunction in calves.

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 81 m-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 (475 +/- 77% 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

Condition physique et capacité respiratoire mitochondriale dans le muscle squelettique de cheval

We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0–2.5 mg) permeabilized muscle fibres sampled from triceps brachii of healthy horses. The present investigation on horse skeletal muscle has tested the methodology used to study mitochondrial function in muscle microbiopsies by high-resolution respirometry to define reference protocols for horses (from sampling procedure to data analysis).Nous avons appliqué la respirométrie à haute résolution et mis au point des protocoles de titration pour étudier la physiologie mitochondriale dans des microbiopsies musculaires prélevées au niveau du triceps brachial de chevaux sains. Ces études ont pour objet de valider la méthodologie et de définir des protocoles de référence pour les chevaux

Assessment of reactive oxygen species production in cultured equine skeletal myoblasts in response to conditions of anoxia followed by reoxygenation with or without exposure to peroxidases.

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-reoxygenation– treated 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