Influence of Epinephrine Infusion and Transportation Before Slaughter on Proteases Activity in Rabbit Muscles

The objective of the present study was to determine if modificationswould occur due to epinephrine perfusion and simulating stressful situations (2 μg/ kg/min, an animal)and transportation,causing change of the values of extractable proteinconcentrations, SDS PAGE profiles and the calpain calpastatin complex in silver rabbitlongissimus muscles resulting in consequent changes in meat tenderness. Approximately60 standard rabbits, 70 days of age, were weighed and randomly assigned to epinephrineand transport treatments along with their controls at 3 times: immediately after slaughter(time 0), 24 hr and 7 days post mortem. The results showed there was a significant(p<0.05) lower value of extractable protein concentrations for treatments in controlsamples than the stress treated ones after 7 days of storage. Also, the comparison of SDSPAGE profiles at times 0 and seven days exhibited several differences due to the originof the samples, especially around 30 KD, the intensity of the band is similar in allsamples at time 0 while it decreases after seven days of storage in all samples except forthose from the epinephrine treatment. On the contrary, after seven days of storage, theresults indicated that dot blots against calpain were lower in the epinephrine sampleswhile they were the highest in control treatments. Transport samples had an intermediateposition. The results showed that epinephrine infusion and transport certainly modifiedmuscular protein degradation. Therefore, variability in the rate of meat tenderization mayarise as a result of stress induced activity or suppression of key proteolytic enzymesinvolved in myofibrillar protein turnover. Those alterations are due to modifications ofthe calpain calpastatin complex. The decrease in protein degradation was due to adecrease in calpain concentration.