Titrimetric determination of muscle buffering capacity (beta mtitr) in biopsy samples.
Abstract: In vitro titration of muscle homogenates has been used to assess muscle buffering capacity (beta mtitr) in a variety of species. In the present study, factors likely to affect the estimation of beta mtitr were investigated. Also, values of beta mtitr from normal Thoroughbred horses are presented. A non-linear titration curve was obtained with addition of HCl to muscle homogenates. As a result, beta mtitr is expressed as the mumol H+ required to change the pH of 1g of dry muscle or wet muscle from 7.1 to 6.5. An effect of dilution on the initial pH was found below 40 mg wet muscle per ml homogenising reagent (10 mg dry muscle per ml) and on beta mtitr below 10 mg wet muscle. As a result, 40 mg wet muscle or 10 mg dry muscle per ml was chosen as the minimum concentration for determination of beta mtitr. Incubation of homogenates up to 60 mins did not affect beta mtitr significantly. As a mean, beta mtitr in wet muscle was approximately 25 per cent higher compared to dry muscle. The beta mtitr of dry muscle was increased by approximately 18 per cent when HCO3- was added in an amount equivalent to the calculated HCO3- content of wet muscle at rest. The homogenisation process resulted in complete loss of adenosine triphosphate and phosphocreatine with only small changes in adenosine diphosphate and adenosine monophosphate. It was concluded that the estimates of beta mtitr did not include any contribution from 'dynamic' buffering via rephosphorylation of adenosine diphosphate by phosphocreatine, and in dry muscle it was accounted for mainly through physico-chemical buffering by phosphates, proteins and dipeptides. beta mtitr determined in biopsy samples of muscle from 20 Thoroughbred horses ranged from 100.8 to 131.8 mumol H+/g dry muscle pH 7.1 to 6.5 (mean 121.2, sd +/- 7.4).
Publication Date: 1991-05-01 PubMed ID: 1884700DOI: 10.1111/j.2042-3306.1991.tb02753.xGoogle Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research study is attempting to measure the muscle buffering capacity, also known as beta mtitr, in muscle biopsy samples of thoroughbred horses. This is achieved through an in vitro titration of muscle homogenates, and the study also investigates factors that could affect the estimation of beta mtitr.
Methodology
- The research team used in vitro titration of muscle homogenates to study muscle buffering capacity, estimating the muscle buffering capacity based on the amount of HCl added to muscle homogenates.
- The measure applied on beta mtitr is the micromoles of H+ used to change the pH level from 7.1 to 6.5 in 1 gram of either dry or wet muscle.
- The researchers conducted tests to understand how dilution affects the initial pH, concluding that dilution impacts the initial pH when the solution contains less than 40 mg wet muscle per ml of homogenising agent.
- Similar tests were conducted to understand the impact of dilution on beta mtitr, showing that significant impact was observed when the concentration was below 10 mg of wet muscle. Consequently, the team selected 40 mg of wet muscle or 10 mg of dry muscle per ml as the minimum concentration for the experiments.
Findings
- According to their findings, beta mtitr was approximately 25 percent higher in wet muscle than in dry muscle.
- The result also showed that incubation of homogenates for up to 60 minutes did not significantly affect beta mtitr.
- The study found that when bicarbonate was added to dry muscle in amounts equivalent to what the wet muscle would naturally contain, the dry muscle’s beta mtitr increased by about 18 percent.
Interpretation and Conclusion
- The researchers concluded that the beta mtitr estimates did not factor in ‘dynamic’ buffering from the rephosphorylation of adenosine diphosphate by phosphocreatine, which is a biochemical process where high-energy phosphate groups are transferred.
- The study also revealed that the homogenisation process resulted in the complete loss of adenosine triphosphate and phosphocreatine, with only minor variations in adenosine diphosphate and adenosine monophosphate. This observation implies that beta mtitr in dry muscle relies largely on physico-chemical buffering by proteins, phosphates, and dipeptides.
- The research study also found considerable variability in the muscle buffering capacity of biopsy samples from different horses.
Cite This Article
APA
Marlin DJ, Harris RC.
(1991).
Titrimetric determination of muscle buffering capacity (beta mtitr) in biopsy samples.
Equine Vet J, 23(3), 193-197.
https://doi.org/10.1111/j.2042-3306.1991.tb02753.x Publication
Researcher Affiliations
- Department of Comparative Physiology, Animal Heath Trust, Newmarket, Suffolk, UK.
MeSH Terms
- Adenosine Diphosphate / analysis
- Adenosine Monophosphate / analysis
- Adenosine Triphosphate / analysis
- Animals
- Bicarbonates / pharmacology
- Biopsy / veterinary
- Buffers
- Freeze Drying
- Horses / metabolism
- Hydrogen-Ion Concentration
- Muscles / chemistry
- Muscles / metabolism
- Phosphocreatine / analysis
- Reproducibility of Results
- Time Factors
Citations
This article has been cited 5 times.- Bishop D, Edge J, Mendez-Villanueva A, Thomas C, Schneiker K. High-intensity exercise decreases muscle buffer capacity via a decrease in protein buffering in human skeletal muscle. Pflugers Arch 2009 Sep;458(5):929-36.
- Gibala MJ, Little JP, van Essen M, Wilkin GP, Burgomaster KA, Safdar A, Raha S, Tarnopolsky MA. Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. J Physiol 2006 Sep 15;575(Pt 3):901-11.
- Bogdanis GC, Nevill ME, Boobis LH, Lakomy HK, Nevill AM. Recovery of power output and muscle metabolites following 30 s of maximal sprint cycling in man. J Physiol 1995 Jan 15;482 ( Pt 2)(Pt 2):467-80.
- Greenhaff PL, Harris RC, Snow DH, Sewell DA, Dunnett M. The influence of metabolic alkalosis upon exercise metabolism in the thoroughbred horse. Eur J Appl Physiol Occup Physiol 1991;63(2):129-34.
- Sewell DA, Harris RC, Marlin DJ, Dunnett M. Estimation of the carnosine content of different fibre types in the middle gluteal muscle of the thoroughbred horse. J Physiol 1992 Sep;455:447-53.
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