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Topic:Biochemistry
The study of biochemistry in horses encompasses the chemical processes and substances that occur within equine organisms. This field investigates the molecular interactions and pathways that are fundamental to horse physiology, including metabolism, enzyme activity, and genetic expression. Key areas of interest include the examination of metabolic disorders, nutrient absorption, and the biochemical basis of muscle function and energy production. Researchers utilize biochemical analysis to understand health and disease mechanisms in horses, contributing to the development of diagnostic tools and therapeutic strategies. This page gathers peer-reviewed studies and scholarly articles that explore various biochemical processes and their implications for equine health and performance.
Metabolic response of equine muscle to intermittent maximal exercise. Four thoroughbred horses performed 4 gallops (G1-G4) with intervals of 5 min. With one exception, gallops were sustained at maximal speed over 620 m. Muscle biopsy samples of the middle gluteal and brachiocephalicus were taken before, during, and after exercise and assayed for ATP and intermediary metabolites. The results showed a major involvement of the brachiocephalicus, in addition to the middle gluteal, during galloping. In three horses, who were clearly fatigued, muscle ATP decreased by up to 50% by the end of G4. This was matched by an equal rise in inosine 5'-monophosphate. Pronounced ...
Breed and species comparison of amino acid transport variation in equine erythrocytes. The amino acid permeability of red blood cells from Equus caballus (thoroughbred, Arab, shire and pony), E przewalskii (Przewalski's horse), E asinus (donkey and mule) and E burchelli (common or plains zebra) was measured. Individual animals exhibited stable but widely differing rates of L-[U-14C]alanine uptake in the range 5 to 1554 mumol (litre cells)-1 h-1 (0.2 mM extracellular L-alanine, 37 degrees C). Of the thoroughbreds tested, 30 per cent had red blood cells which were essentially impermeable to L-alanine (5 to 10 mumol (litre cells)-1 h-1, giving transport rates similar to those found...
Failure of superoxide dismutase to alter equine arachidonic acid-induced platelet aggregation, in vitro or ex vivo. Superoxide dismutase (SOD), a free radical scavenger with anti-inflammatory activity, was administered IM to horses. Ex vivo platelet aggregation in response to arachidonic acid was monitored to determine whether exogenous SOD altered equine platelet prostaglandin metabolism. Preparations of platelet-rich plasma obtained before SOD administration were incubated with different concentrations of SOD and were aggregated with arachidonic acid. Superoxide dismutase did not exert a demonstrable effect, either ex vivo or in vitro. Aspirin abolished arachidonic acid-induced platelet aggregation in vit...
Glycogen depletion patterns in horses competing in day 2 of a three day event. Muscle biopsy samples were collected from the left middle gluteal muscle of the horses participating in day 2 (speed and endurance test) of a three day event. Six Thoroughbred horses were biopsied the day before and within 30 minutes of completion of the speed and endurance test. Serial muscle sections were reacted histochemically for myosin adenosine triphosphatase activity after acid pre-incubation to demonstrate Type I, IIA and IIB fibers and the glycogen content in the individual fibers was assessed using the periodic acid Schiff (PAS) reaction. Total glycogen in muscle was measured fluoro...
Effects of intrauterine infusion of Escherichia coli endotoxin in anestrous and steroid treated pony mares. This study was conducted to determine if Escherichia coli endotoxin was absorbed from the equine uterus and if exogenous progesterone and estrogen affected the absorption of intrauterine endotoxin. Six mature anestrous pony mares were used in three consecutive crossover experiments (Periods) with a 14 day recovery between each period. Mares were randomly assigned to one of two treatment groups (three mares per group) and received an intrauterine infusion of either saline or endotoxin. Treatment groups were reversed and readministered after 14 days completing a crossover design (Period 1). Duri...
Characterization of a novel Na+-independent amino acid transporter in horse erythrocytes. Horse erythrocytes are polymorphic with respect to L-alanine permeability. The present investigation compared the specificity, kinetics and cation-dependence of erythrocyte amino acid transport in two groups of thoroughbred horses, those with erythrocyte L-alanine permeabilities in the range 5-15 mumol/h per litre of cells (0.2 mM extracellular L-alanine, 37 degrees C) (transport-negative type) and those with L-alanine permeabilities in the range 450-700 mumol/h per litre of cells (transport-positive type). Transport-positive cells are shown to possess a novel high-affinity, stereospecific, Na...
Trials of serotonin, substance P and alpha 2-adrenergic receptor effects on the equine large colon. Some support for both serotonin and substance P as biotransmitters in the equine large colon is presented. Close arterial injections of small quantities of each of these were effective, respectively, in stimulating marked increases in coordinated pressure peaks in the vicinity of the pelvic flexure, with modest (serotonin) or marked (substance P) increase in colon artery blood flow. Both the acaricide, amitraz, and the tranquilizer xylazine appeared to act on the equine large colon via yohimbine-sensitive alpha 2-adrenergic receptors.
Changes in blood constituents accompanying exercise in polo horses. There have been several studies of biochemical changes in horses doing intense exercise such as Thoroughbred and Standardbred racehorses and in horses performing exercise over a long period of time such as endurance horses and three-day eventing horses, but we are not aware of studies with polo horses. Blood samples were taken from 18 polo horses at rest, immediately after playing 2 chukkers of indoor polo, and after a 15 minute rest period. Each horse was studied at 2 different games. The blood samples were analyzed for lactic acid, protein, sodium, potassium, chloride, calcium, phosphorus, H...
Antigenic determinants of acylphosphatase from porcine skeletal muscle. Analysis of the quantitative precipitin reaction of acylphosphatase from porcine skeletal muscle with rabbit antiserum indicated the presence of at least two antigenic determinants on the porcine enzyme molecule. Immunological cross-reactivities of acylphosphatases from equine and rabbit skeletal muscles were examined. In double immunodiffusion with the antiserum, the precipitin lines of the porcine and equine enzymes completely fused, while the rabbit enzyme gave no precipitin line. The reaction between the 125I-labeled porcine enzyme and its antibody was inhibited to the same extent by the p...
Hybrids from equine LH: alpha enhances, beta diminishes activity. LH hybrids were prepared by combining eLH alpha and eLH beta with the corresponding subunits of oLH, pLH and hCG. Recombinants were isolated by gel filtration and assessed by SDS-polyacrylamide gel electrophoresis under both dissociating and non-dissociating conditions. All combinations of subunits produced hybrid LH molecules. Hybrids prepared by combining eLH beta with oLH alpha, pLH alpha or hCG alpha were very inactive in rat radioligand and Leydig cell in vitro bioassays. Hybrids prepared with eLH alpha were very active in both assays. The greatest potentiating activity was observed when ...
[Hyalurodinase activity of beta-hemolytic streptococci of the Lancefield group C]. A total of 110 strains of beta-hemolytic streptococci, belonging to serogroup C (Lancefield), isolated from horses (71 S. zooepidemicus, 27 S. equisimilis and 12 S. equi) as well as 5 reference strains were tested for their ability to produce hyaluronidase. The determinations were carried out in a culture test on agarose gel and in a liquid test system (turbidity test according to DiFerrante). The results of both methods used showed that the three Streptococcus species could be differentiated by the relative quantitative determination of hyaluronidase activity. S. equisimilis strains produce 5...
Plasma and serum concentrations of phenylbutazone and oxyphenbutazone in racing Thoroughbreds 24 hours after treatment with various dosage regimens. The plasma and serum concentrations of phenylbutazone (PBZ) and oxyphenbutazone were measured in 158 Thoroughbred horses after various doses of PBZ wer given. All horses were competing or training at racetracks in various parts of the country. All horses used in the study had not been given PBZ 24 hours before they were placed on a specific dosage schedule. Samples were collected 24 hours after the last PBZ administration. Four grams of PBZ were given daily by stomach tube, paste, or tablet for 3 days. On day 4, 24 hours before sample collection, an IV dose of 2 g of PBZ was given, regardless ...
Estrogen metabolites in equine ovarian follicles: gas chromatographic-mass spectrometric determinations in relation to follicular ultrastructure and progestin content. Equine follicular fluid was aspirated at various developmental stages (viable, preovulatory and atretic) determined by ultrastructural study. Estrogens and progestins were analyzed by gas chromatography-mass spectrometry associated with stable isotope dilution. Progesterone and 17-hydroxyprogesterone were the principal progestins of the preovulatory and viable follicles. Among the catechol estrogens, 2-hydroxy-estradiol was particularly abundant in the preovulatory follicle and its definitive identification was made by the scan of a full mass spectrum.
The biosynthesis of 3 beta-hydroxy-5,7-androstadien-17-one by the horse fetal gonad. Horse fetal gonadal tissue was incubated with 3 beta-hydroxy-5,7-pregnadien-20-one and 5,7-cholestadien-3 beta-ol and it was shown that both substrates were converted to 3 beta-hydroxy-5,7-androstadien-17-one. These findings support the proposal that in this tissue there is a 5,7-diene pathway producing 3 beta-hydroxy-5,7-androstadien-17-one, the putative precursor of equilin in the placenta.
Iron deposition in apoferritin. Evidence for the formation of a mixed valence binuclear iron complex. A preliminary EPR investigation of iron accumulation in apoferritin has identified paramagnetic species generated during the early stage of iron deposition within the apoprotein shell. A featureless resonance at g' = 4.3, attributable to solitary high spin Fe3+ ions bound to the protein, is generated when Fe(II) is added to apoferritin at a level of 0.5 Fe/subunit (12 Fe/molecule) followed by air oxidation. This resonance accounts for 36% of the added iron. The remainder is EPR-silent and is probably present as oligomeric Fe3+ species. The intensity of the g' = 4.3 signal is reduced 3-fold upo...
The effect of training and physical exercise on the energetic metabolism of equine erythrocytes. Erythrocytes, due to their simple metabolic processes, differ greatly from nucleated
cells. Their main metabolite of glycolysis is 2,3-Diphosphoglycerate (2,3-DPG), which
serves also as an energy store for producing ATP in the pyruvate kinase reaction. 2,3-DPG
modifies also the affinity of haemoglobin for oxygen (4). Increase in the concentration of
2,3-DPG, ATP and body temperature, or a decrease in the pH value of blood causes
decreased affinity of haemoglobin for oxygen as blood transverses muscle capillaries,
facilitating oxygen delivery. In equine erythrocytes, the level of ATP is s...
Laboratory evaluation of aqueous humor in the healthy dog, cat, horse, and cow. Using routinely available clinical laboratory methods, aqueous humor samples were evaluated from 12 healthy dogs, 15 healthy cats, 7 healthy horses, and 6 healthy cows. Aqueous humor was almost acellular; cells that were present had degenerated beyond recognition. Protein concentration was low; only albumin was detectable on electrophoresis. Creatine phosphokinase and lactate dehydrogenase isoenzymes were not detected. Artifacts induced by sampling were insignificant compared with alterations in aqueous humor composition that occur with ocular diseases.
Turbidimetric measurement of IgG(T) in the serum of healthy Thoroughbreds and ponies. The turbidimetric analysis of IgG(T) in the serum of horses is described. Reference values are provided for 'worm-free' ponies (2.6 +/- 0.7 g/litre), stabled Thoroughbreds two years old and over (4.1 +/- 1.3 g/litre), grazing Thoroughbred broodmares (7.1 +/- 2.4 g/litre) and regularly wormed adult and young ponies grazing pasture contaminated with intestinal parasite eggs and larvae.
[Comparative characteristics of the vitreous body proteins in vertebrates]. Using disc-electrophoresis in polyacrylamide gel and immunochemical methods, studies have been made on proteins from the vitreous body of mammals (albino mouse, rat, guinea pig, pig, dog, cat), birds (hen), amphibians (the frog Rana ridibunda) and fish (the perch Perca fluviatilis). It was found that vitreous body proteins in man and animals include both the specific proteins and those of the blood serum. During evolution, specific antigens of the vitreous body attained strict species specificity, although some of them preserved the initial properties.
Pharmacokinetic studies of theophylline in horses. The pharmacokinetics of theophylline were determined in Standardbred trotters after single intravenous and oral administration. A bi-exponential equation was fitted to the intravenous data and a tri-exponential equation to the oral data. The biological half-life of theophylline was found to be 14.8 h, the volume of distribution 1.02 l/kg and the total plasma clearance 0.86 ml/kg/min. The oral absorption of the drug was complete (bioavailability 108%) and rapid (absorption half-life 0.4 h).
Application of the peroxidase-antiperoxidase procedure to the localization of pituitary hormones and calcitonin in various domestic animals and human beings. Specific cell populations in the pituitary glands of the rat, cat, pig, and human being were positive for thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). When reacted with prediluted rabbit anti-human TSH, LH, and FSH, antisera were not positive for the demonstration of these hormones in the horse, cow, or dog. Immunocytochemical staining was obtained in the horse, cow, and dog by the use of a primary antiserum against a specific beta-subunit of bovine TSH. The immunocytochemical staining of TSH, LH, FSH, adrenocorticotropic hormone, growth ...
Measurement of IgG in equine blood by immunoturbidimetry and latex agglutination. This paper describes the quantitative measurement of IgG concentrations in equine blood/serum by turbidimetric analysis and the qualitative assessment using latex agglutination. The concentration of IgG in foal serum measured by turbidimetry correlated well with the results obtained by radial immunodiffusion (r = 0.91) and the gamma-globulins estimated from the electrophoresis of serum on cellulose acetate (r = 0.92). The method, using antibody-coated latex beads, to detect foals with serum IgG concentrations of less than 4 g/litre (whole blood less than 2 g/litre) proved to be accurate in 96 ...
Inhibition of lipases by proteins. A kinetic study with dicaprin monolayers. We report further investigations on protein inhibition of pancreatic and microbial lipases carried out with the monolayer technique. When beta-lactoglobulin A, melittin, serum albumin, myoglobin, and a protein inhibiting lipase from soybean were preincubated with a dicaprin film at a surface pressure of 35 dynes/cm, no activity was detected with horse pancreatic or Rhizopus delemar lipases. By contrast, Rhizopus arrhizus and Geotrichum candidum lipase activities were not impaired under the same conditions. Experiments using mixed lipid-protein film transfer clearly show that the inhibition of ...
Effects of phenylbutazone and anabolic steroids on adrenal and thyroid gland function tests in healthy horses. Adrenal and/or thyroid gland function tests were evaluated in horses at various times during short-term therapy with phenylbutazone, stanozolol, and boldenone undecylenate. There were no significant treatment or time effects on mean basal plasma cortisol concentrations in horses during treatment with the following: phenylbutazone, given twice daily (4 to 5 mg/kg, IV) for 5 days; stanozolol, given twice weekly (0.55 mg/kg, IM) for 12 days; boldenone undecylenate, given twice weekly (1.1 mg/kg, IM) for 12 days; or nothing. There was no significant effect of phenylbutazone treatment on the change...
Glycosaminoglycan content of glomerular and tubular basement membranes of various mammalian species. A spectrophotometric assay was applied for quantitation of sulfated glycosaminoglycans in digested renal basement membranes of six mammalian species. The conditions of digestion and the accuracy of the assay were evaluated. Papain digestion and alkaline treatment appeared to be most effective for solubilization. Basement membrane preparations obtained by sonication contained more glycosaminoglycans than those isolated by detergent treatment. Glomerular basement membranes had generally a higher glycosaminoglycan content than tubular basement membranes.
The amino acid sequence of equine milk lysozyme. The amino acid sequence of equine milk lysozyme has been elucidated. The study involves the determination of the sequence of the N-terminal region of the whole protein, cyanogen bromide fragments, tryptic and chymotryptic peptides and fragments produced by chemical cleavage after tryptophan residues. The protein consists of a single chain of 129 amino acid residues and has a Mr of 14647. While equine milk lysozyme has the essential features of a c(chick)-type lysozyme, there is only 51% sequence homology with human milk lysozyme and 50% with domestic hen egg white lysozyme. Some of the implica...
Alkylation of bronchiolar epithelial cells by 3-methylindole metabolites in the horse. Autoradiographs of horse-lung explants incubated with [3H]3-methylindole (3MI) showed 8 times greater labeling per area to bronchiolar epithelial cells than to the interalveolar septa. Incubations of horse-lung microsomes with [14C]3MI resulted in alkylation of microsomal proteins, which could be reduced by exogenous glutathione. An apparent covalent adduct of glutathione and 3MI was isolated from these incubations. These results suggest that the target cells of 3MI-induced injury in the horse, the bronchiolar epithelial cells, are alkylated by an electrophilic 3MI intermediate.
Characteristics of Mycoplasma strains isolated from stallion semen. Eleven mycoplasma strains were isolated from the semen of 24 stallions. Eight of these strains were identified as Mycoplasma equigenitalium. Three strains which hydrolized arginine could not be identified. The growth inhibition test with immune sera against M. arginini and M. equirhinis was negative. Antibiotic sensitivity test showed that all strains were sensitive to four antibiotic of tetracycline group (oxytetracyclin, minocycline, transcycline and vibramycin). Lincomycin and gentamycin appeared to be the most active against all the strains. Comparative analysis of routine semen examinatio...
