Pork quality and the expression of stress protein Hsp 70 in swine

Abstract

The expression of heat shock protein with a molecular weight of 70 kDa (Hsp 70) in porcine tissue and its potential relationship to stress susceptibility was studied. Twelve pigs, four of each genotype (NN, Nn, and nn) for halothane sensitivity were slaughtered. At 45 min postmortem, several tissues (liver, kidney, spleen, skeletal and cardiac muscle, and adrenal gland) were sampled for Hsp 70 analysis. At 24 h postmortem, longissimus and semimembranosus muscle were sampled for assessment of meat quality. Water-holding and water-binding capacity, color, and protein denaturation of samples from halothane-positive animals indicated that these animals had been stressed. Homozygous nn pigs demonstrated a lower pH45 and higher L-value at 48 h than their NN and Nn counterparts (P < .05). The longissimus, but not semimembranosus, muscle of nn pigs demonstrated lower water-holding capacity and greater protein denaturation than that of NN or Nn pigs (P < .05). The water-binding capacity of both longissimus and semimembranosus was less in nn than in Nn or NN pork (P < .05). Using one-dimensional PAGE and Western blotting, Hsp 70 was shown to be present in all tissues examined. With two-dimensional PAGE followed by blotting, the presence of the cognate and inducible form of Hsp 70 was investigated. There did not seem to be a relationship between stress (based on meat quality) and expression of either form of Hsp 70.