Protein synthesis in myocardial ischaemia and infarction
Protein synthesis, as indicated by the in vitro and in vivo incorporation of isotopic amino acids into myocardial proteins, was determined at various time intervals after ligation of the left coronary artery. The results show that the in vitro incorporation of l-[4,5-3H]leucine and l-[U-14C]lysine into the soluble protein and actomyosin fractions of heart muscle slices was normal up to 6 h after the onset of ischaemia. The rate of amino acid incorporation was significantly higher 12 h after occlusion of the left coronary artery and remained elevated for at least 2 months. After 3 months, the rate of amino acid incorporation into both protein fractions returned to normal. Protein synthesis was elevated in both the uninfarcted and infarcted areas of the myocardium. Studies on the in vivo incorporation of l-[4,5-3H]leucine into total myocardial proteins also showed that protein synthesis was normal up to 6 h after occlusion of the left coronary artery. © 1971.