In plasma membranes of intact cells an enzymatic pump actively transports sodium ions inward and potassium outward. preparations broken it appears as adenosine triphosphatase dependent on magnesium, sodium, together. this a phosphorylated intermediate is formed from triphosphate in the presence hydrolyzed with addition ions. The normal was not split by diphosphate. However, selective poisoning N-ethylmaleimide or partial inhibition low magnesium ion concentration yielded diphosphate...

Abstract Physiological ligands of (sodium-potassium)-dependent adenosine triphosphatase influenced the sensitivity enzyme to inhibitor, ouabain. Phosphorylation native is accelerated by sodium ions, while potassium ions accelerate dephosphorylation. Exposure phosphoenzyme ouabain slowed its turnover and rendered it insensitive ion. This action did not require free magnesium ion was high concentrations The ouabain-treated gradually yielded a dephosphoenzyme which could be rephosphorylated...

Calcium ion inhibits (Na + K )-ATPase (EC 3.6.1.3) primarily by reducing the rate of phosphorylation step. Inhibition this step is competitive with respect to Na and noncompetitive Mg ++ . Although Ca acts reduce step, high concentrations are required steady-state levels phospho-enzyme, alone stimulates a slow enzyme. In presence phospho-enzyme formed sensitive ouabain, its low when present. If concentration low, phosphoenzyme in insensitive reacts readily ADP. The reactivity -dependent ADP...

After intravenous (i.v.) injection, acepromazine was distributed widely in the horse (Vd = 6.6 litres/kg) and bound extensively (greater than 99%) plasma proteins. Plasma levels of drug declined with an alpha half-life 4.2 min, while beta phase or elimination 184.8 min. At a dosage level 0.3 mg/kg detectable for 8 h post dosing. The whole blood partitioning 46% 54% erythrocyte phase. Penile prolapse clearly evident at doses from 0.01 to 0.4 i.v., duration extent protrusion were dose related....

SUMMARY The locomotor responses of horses given morphine and fentanyl were blocked or lessened by administration naloxone acepromazine. Naloxone at the dosage 0.015 mg/kg completely activity induced in (0.020 body weight). stimulation produced 2.4 was reduced 75% mg/kg). Acepromazine partially to morphine. This blockade reached its peak about 30 minutes after acepromazine ( iv ) lasted more than 6 hours. Simultaneous associated with substantial respiratory depression for 4 hours both drugs....

beta-Glucuronidase from Patella vulgata, Helix aspersa, pomatia, and bovine liver were evaluated for usefulness in routine hydrolysis of drug-glucuronic acid conjugates equine urine samples. Factors affecting the reaction rate (enzyme concentration, ligand temperature, pH) optimized. A 3-h incubation at 65 degrees C with 5000 U beta-glucuronidase P. vulgata per milliliter resulted complete all morphine glucuronide Not only was enzyme preparation most cost-effective source studied, but also...

ABSTRACT Bupivacaine is a local anesthetic widely used in equine and human medicine. Use of bupivacaine performance horses regulated because its ability to block pain means that it can be misused for advantage horses. In racing regulation, classified by the Association Racing Commissioners International (ARCI) as Class 2 Penalty A Foreign substance, detection which lead significant penalties. horses, metabolized Phase‐I hydroxylation yield 3‐hydroxybupivacaine, then glucuronidated Phase‐II...

Although lithium ion substitutes poorly for potassium in the reaction cycle of (Na+ + K+)-ATPase (ATP phosphohydrolase, EC [3.6.1.3][1]), it consistently activated this enzyme presence sodium and potassium. In contrast, rubidium ion, a much more effective substitute than lithium, was generally inhibitory Li+ did not appear to activate by stimulating its phosphorylation from ATP. Rather, Na+ required stimulate ATPase activity, directly (though weakly) stimulated dephosphorylation. Under...

Cocaine-induced hepatotoxicity has been reported in human beings and is well documented mice. One interesting feature of this toxicity that appears to be common both species an apparent shift the intraacinar site necrosis under circumstances known alter cocaine metabolism. However, evidence subjects limited, studies elucidating mechanism phenomenon cannot performed beings. Although future mice may define basis mechanism, current a somewhat fragmented composite using different mouse strains...

Abstract Tall fescue toxicosis and other maladies in livestock result from the ingestion of vasoconstrictive ergot alkaloids produced by fungal endophytes associated symbiotically with grass. In order to facilitate future analyses grass extracts considered responsible for outbreak related diseases, we examined electrospray ionization mass spectra specific under conditions that permit protonation. Our purposes were both record interpretation mechanisms fragmentation derive commonalities would...

The characteristics of complexes [ 3 H]ouabain with (Na + K )-ATPase [Mg 2+ -dependent, , )-activated ATP phosphohydrolase, EC 3.6.1.3.] formed in vitro the presence various ligands were compared using partially purified rat brain and dog heart enzyme preparations homogenates. differences ouabain-enzyme detected by monitoring dissociation rates media low ionic strength. It appeared that there are at least three different forms complex prepared enzyme. Mg P i was stable unaffected added to...

Summary The highest no effect doses (HNEDs) for the local anaesthetic (LA) effects of procaine, cocaine, bupivacaine and benzocaine were determined using heat lamp/hoof withdrawal model Kamerling et al . (1985b) abaxial sesamoid block anaesthesia. lamp rapidly (4 or 5 s) increased temperature superficial skin layers pastern to about 90°C, at which point animal sharply withdrew its hoof. Effective LA blockade precluded this response temperatures exceeded 120°C. Thermal stimulus experiments...

Clenbuterol is a β 2 agonist/antagonist bronchodilator marketed as Ventipulmin ® and the only member of this group drugs approved by US Food Drug Administration (FDA) for use in horses. class 3 drug Association Racing Commissioners International (ARCI) classification system; therefore, its identification postrace samples may lead to sanctions. Recently, sensitivity testing clenbuterol has been substantially increased. The objective study was determine ‘detection times’ after administration...

This report describes the development of a behaviour chamber and validation to measure locomotor activity horse. Locomotor was detected by four Mini‐beam sensors recorded on data logger every 5 min for 22 h. Horses were more active during daytime than in evening, which at least partially related human their surroundings. To validate ability chambers detect changes activity, fentanyl citrate xylazine HCl, agents well‐characterized as stimulant depressant, respectively, administered five...