Titrimetric determination of muscle buffering capacity (beta mtitr) in biopsy samples.

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.