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

The objective of the present study was to determine if modifications would occur due to epinephrine perfusion and simulating stressful situations (۲ µg/ kg/ min, an animal)and transportation,causing change of the values of extractable protein concentrations, SDS PAGE profiles and the calpain calpastatin complex in silver rabbit longissimus muscles resulting in consequent changes in meat tenderness. Approximately ۶۰ standard rabbits, ۷۰ days of age, were weighed and randomly assigned to epinephrine and transport  treatments along with their controls at ۳ times: immediately after slaughter (time ۰), ۲۴ hr and ۷ days post mortem. The results showed there was a significant (p<۰.۰۵) lower value of extractable protein concentrations for treatments in control samples than the stress treated ones after ۷ days of storage. Also, the comparison of SDS PAGE profiles at times ۰ and seven days exhibited several differences due to the origin of the samples, especially around ۳۰ KD, the intensity of the band is similar in all samples at time ۰ while it decreases after seven days of storage in all samples except for those from the epinephrine treatment. On the contrary, after seven days of storage, the results indicated that dot blots against calpain were lower in the epinephrine samples while they were the highest in control treatments. Transport samples had an intermediate position. The results showed that epinephrine infusion and transport certainly modified muscular protein degradation. Therefore, variability in the rate of meat tenderization may arise as a result of stress induced activity or suppression of key proteolytic enzymes involved in myofibrillar protein turnover. Those alterations are due to modifications of the calpain calpastatin complex. The decrease in protein degradation was due to a decrease in calpain concentration.