We compared the ability of 2 alpha2-adrenergic receptor antagonists, atipamezole and yohimbine, to reverse medetomidine-induced CNS depression and cardiorespiratory changes in lambs. Twenty lambs (7.8 +/- 2.6 kg) were randomly allotted to 4 treatment groups (n = 5). Each lamb was given medetomidine (30 micrograms/kg of body weight, IV), followed in 15 minutes by IV administration of atipamezole (30 or 60 micrograms/kg), yohimbine (1 mg/kg), or 0.9% NaCl (saline) solution. Medetomidine caused lateral recumbency in 1 to 2 minutes in all treated lambs. Medetomidine significantly (P < 0.05) decreased heart rate at 5 and 10 minutes after its administration. Heart rate remained above 120 beats/min, and severe bradycardia (< 70 beats/min) and other arrhythmias did not occur throughout the study. Medetomidine also induced tachypnea in all treated lambs. The tachypnea was abolished by atipamezole and yohimbine, but not by saline solution administration. The medetomidine-induced tachypnea did not significantly affect arterial pH and PaCO2. Arterial oxygen tension was within acceptable range (PaO2 = 71 to 62 mm of Hg), but was lower than expected. Administration of atipamezole, yohimbine, or saline solution did not change PaO2 significantly. Lambs treated with 30 or 60 micrograms of atipamezole/kg were able to walk unassisted in 2.4 +/- 0.4 and 2.3 +/- 0.7 minutes, respectively, whereas yohimbine-and saline-treated lambs did not walk unassisted until 15.6 +/- 2.7 and 73.0 +/- 6.8 minutes later, respectively. Results of this study indicated that medetomidine is a potent CNS depressant in lambs. Atipamezole at dosage of 30 or 60 micrograms/kg was equally effective, and was more effective in antagonizing medetomidine-induced CNS depression than was yohimbine.

The function of several intrinsic muscles of the fore-and hind limbs of 5 ponies walking normally was evaluated via surface electromyography. Electromyographic signals were band-pass filtered, rectified, linear enveloped, and standardized to the stride duration. Mean data from the muscles of the left and right limbs that were obtained from at least 30 strides in 2 recording sessions were recorded as electromyographic signals-time curves. The timing of muscle activity was determined from these graphs. On the basis of the major peaks in the electromyographic signal, muscle functions were identified. In the forelimb, the extensor carpi radialis muscle was involved in extension of the carpus at the end of the swing phase of the stride, and it provided support to flexion of the cubital joint at the beginning of the swing phase. The common digital extensor muscle extended the distal joints of the forelimb at the end of the swing phase. The ulnaris lateralis muscle provided support to extension of the cubital joint at the beginning of the stance phase, and the flexor carpi radialis muscle flexed the carpus at the beginning of the swing phase. The flexor carpi ulnaris muscle extended the cubital joint at the end of the swing phase. In the hind limb, the long digital extensor muscle flexed the tarsus at the beginning of the swing phase and extended the digital joints preceding the stance phase. The deep digital flexor muscle prevented overextension of the distal interphalangeal joint during the stance phase and flexion of the digital joints during the swing phase. The gastrocnemius muscle prevented flexion of the tarsus on impact and supported flexion of the femorotibial the beginning of the swing phase.

Strain gauge rosettes were bonded to the dorsal, lateral, medial, and plantar aspects of the third metatarsal bone in the hind limbs of 6 ponies. The maximal compressive principal strain was approximately -600 X 10(-6) m/m, and exceeded the amplitudes of the tensile strains at all aspects of the bone. After transformation, the shear strain and the principal strains parallel and perpendicular to the bone were obtained. The first peak in the bending strain was higher in the dorsal and lateral aspects, and the second peak was higher in the medial and plantar aspects. Young modulus of elasticity was determined in a 4-point bending test at the dorsal and plantar sides; it averaged 19.5 GPa in tension and compression. Applying linear bending theory, the eccentricity of an axial force parallel or a bending force perpendicular to the bone were calculated. The position where the total force penetrated the tarsometatarsal joint surface was largely within the joint surface, indicating that the joint is merely loaded in (eccentric) compression.

This study has been carried out to investigate the augmenting or inhibiting effects of histamine, 5-hydroxytryptamine and their antagonists on the uterine motility. The uterine motility was represented by the magnitude of impulse and the frequency of uterine contraction which was counted by the number of waves on the recording paper. The inhibitory effect of phenoxybenzamine on the response to 5-hydroxytryptamine is the result of drug antagonism. Histamine stimlates or inhibits the motility of smooth muscle through H1 or H2-receptor. The uterine motility was increased through H1-receptor. Histamine induced relaxation by acting through H2-receptor.

To elucidate the action of the cholinergic and adrenergic nerve on isolated gastric fundus smooth muscle of rabbit, the effects of electrical transmural stimulation were investigated in the presence of atropine, cholinergic receptor blocker; phentolamine, nonselective alpha-adrenergic receptor blocker; propranolol, nonselective beta-adrenergic receptor blocker and L-arginine from the isometric contraction of physiological recording system. 1. The contractile response induced by electrical transmural stimulation was increased as the frequency(1~32Hz)-dependent manner on the isolated gastric fundus smooth muscle. 2. The contractile response induced by electrical transmural stimulation was markedly inhibited by the pretreatment of atropine(1 microM). 3. The contractile response induced by electrical transmural stimulation was inhibited by the pretreatment of phentolamine(1 microM). 4. The relaxative response induced by electrical transmural stimulation on presence of atropine (1 microM) was inhibited by the pretreatment of propranolol(1 microM). 5. The relaxative responses on precontraction induced by histamine(10 microM) with guanethidine (50 microM) and atropine(1 microM) by electrical transmural stimulation were incresed by L-arginine(1mM). These fingings suggest that it was the exciatory action of cholinergic and alpha-adrenergic nerve, and the inhibitory action of beta-adrenergic nerve and nonadrenergic noncholinergic nerve on the isolated gastric fundus smooth muscle of rabbit.

Communications between the femoropatellar, medial femorotibial, and lateral femorotibial joints were studied, using fresh equine cadaver specimens. A total of 90 specimens from 45 horses were used. Horses were randomly assigned to 3 groups with 15 horses/group. Each group was assigned an injection site (femoropatellar joint, medial femorotibial joint, or lateral femorotibial joint), and red latex was injected into the respective location of each joint in each group. Immediately after injection, the joints were flexed and extended 100 times. The stifles were frozen in slight flexion, then cut into 1-cm sagittal sections. The communications between the femoropatellar and medial and lateral femorotibial joints were determined. None of the specimens in this study had communication between afl 3 joint compartments. When the femoropatellar joint was injected, 18 of 30 joints (60%) communicated with the medial femorotibial joint, and 1 of 30 (3%) communicated with the lateral femorotibial joint. Injection of the medial femorotibial joint revealed 24 of 30 (80%) joints that communicated with the femoropatellar joint, and 1 of 30 (3%) that communicated with the lateral femorotibial joint. Injection of the lateral femorotibial joint resulted in communication with the femoropatellar joint in 1 of 30 (3%) joints. Communication did not exist between the medial and lateral femorotibial joints.

Loads on the suspensory ligament, deep digital flexor tendon, superficial digital flexor tendon, and long digital extensor tendon of the equine hind limb were determined in ponies by use of implanted strain gauges consisting of silicone rubber tubes filled with mercury. Recordings were made simultaneously with force plate measurements and high-speed film recordings while the ponies were walking. The relationship between strain gauge signals and tendon loads was obtained from tension-strain tests performed after death of the ponies. The suspensory ligament and the 2 digital flexor tendons were loaded during the stance phase, and the extensor tendon was loaded mainly during the swing phase. The loading pattern of the suspensory ligament, with peak loads of 4.6 N/kg of body weight, correlated well with the vertical component of the ground reaction force. Maximal loading of the deep digital flexor tendon was observed during the second half of the stance phase, with peak values of 6.7 N/kg. The superficial digital flexor tendon was loaded maximally at the beginning of the stance phase, with a peak load of 4.1 N/kg, and the long digital extensor tendon was loaded maximally during the swing phase, with a peak load of 0.3 N/kg. Recordings made from this procedure for calibration of the strain gauge signals to tendon load and tendon strain, in combination with the force plate measurements, enabled verification of the results by torque analysis of the lower portion of the hind limb, using the vector of the ground reaction force, limb conformation, and limb geometric configuration. Torque analysis of the lower extremity indicated that the determined tendon loads were in agreement with the recorded ground reaction forces.

Suaeda (S.) asparagoides M∧IQ, one of the halophyte groups, has been used as a folk remedy for digestive disturbances in Korea. However, its pharmacological activity on gastrointestinal motility has not been reported yet. In this study, the effects of this halophyte extracts with various solvent fractions (ethanol, hexane, chloroform, ethyl acetate, butanol, and water) on mice ileal spontaneous motility was examined. All solvent fractions at the concentration of 100 ㎍/ml showed inhibitory actions on spontaneous motility of ileum with the potency order of water greater-than 70% ethanol greater-than hexane much greater-than chloroform greater-than or equal to butanol greater-than or equal to ethyl acetate, respectively.

Neutrophils are present in milk of cows as a means of suppressing invading pathogens during mastitis. However, the manner by which neutrophils traverse the secretory epithelia is still not clear: do they diapedese between epithelial cells or do they kill epithelial cells to gain entry into milk? We investigated the process of bovine neutrophil diapedesis across bovine mammary gland epithelium in vitro. The bovine mammary epithelial cell line MAC-T, grown on collagen-coated filters, formed a confluent monolayer with characteristic tight junctions, basal-apical polarity, and functional barriers to the dye trypan blue. Neutrophils added on the apical surface of the monolayer were stimulated to diapedese across the epithelium by the addition of Staphylococcus aureus (10(7) colony-forming units/ml) to the basal compartment. Light and transmission electron microscopy revealed the series of events for neutrophil transmigration: accumulation of neutrophils on the surface of epithelial monolayer; projection of pseudopods into intercellular junctions and movement of neutrophils between adjacent epithelial cells; and reapproximation of the lateral epithelial cell membranes and reformation of the apical tight junctions after neutrophils crossed the epithelium. Morphologically, epithelial cell damage caused by neutrophil diapedesis was not evident. This in vitro model provides a two-dimensional epithelial sheet by which neutrophil diapedesis can be qualitatively studied under defined conditions. Results of the study suggest a major mode by which bovine neutrophils diapedese across the alveolar epithelia into milk during mastitis.