Erythrocyte osmotic fragility, serum creatine kinase and its isoenzymes related to body weight in porcine malignant hyperthermia

Free radicals and calcium homeostasis: relevance to malignant hyperthermia?

The regulation of intracellular free calcium ions (Ca2+) in skeletal muscle at rest and during contraction depends on mechanisms such as Na(+)-Ca2+ exchangers, Ca(2+)-ATPases, and the voltage-sensitive ryanodine receptor. The susceptibility of these regulatory mechanisms to free-radical-mediated damage may be increased because of their location within the lipid membranes of sarcolemma, sarcoplasmic reticulum, and mitochondrion with resultant uncontrolled increases in myoplasmic Ca2+ concentration and cell death. The potentially fatal pharmacogenetic disorder, malignant hyperthermia (MH), is characterised by muscle rigidity, arrhythmias, lactic acidosis, and a rapid rise in body temperature. The sequence of events responsible for the MH syndrome remains uncertain, but it has been variously ascribed to faults in many of the Ca2+ regulatory mechanisms. In swine the condition is associated with a specific mutation in the ryanodine receptor, whereas in humans the syndrome is genetically heterogenous. Free-radical-mediated peroxidation of membrane lipids and proteins also results in the rapid efflux of Ca2+ from organelles, and the detection of products of free radical reactions in tissue from MH-susceptible individuals using electron spin resonance spectroscopy provides evidence for the involvement of free radicals in the MH syndrome.

Identification by isoelectric focusing of creatine kinase-MM isoforms in the plasma and striated muscle of pigs

Total creatine kinase (CK) and CK-MM isoforms were determined in plasma and longissimus dorsi muscle extracts from normal pigs. Based on their total CK activity, the pigs were divided into two groups. Pigs of group 1 (n = 16) had a mean plasma total CK of 298 +/- 16 U/L and the distribution of the CK-MM isoforms was 65.7 +/- 2.5% CK-MM3, 18.9 +/- 1.6% CK-MM2 and 15.3 +/- 1.5% CK-MM. In group 2 (n = 18; 826 +/- 75 U/L total CK) four isoforms were observed: 3.1 +/- 0.9% CK-MM, 67.9 +/- 3.0% CK-MM3, 21.5 +/- 2.3% CK-MM2 and 7.5 +/- 1.3% CK-MM. The differences between the two groups of pigs were significant (p less than 0.001) for CK-MM1 and the presence of CK-MM. Four CK-MM isoforms were also detected in longissimus dorsi muscle homogenates: 45.6 +/- 8.1% CK-MM, 32.6 +/- 11.7% CK-MM3, 16.6 +/- 2.3% CK-MM2 and 5.1 +/- 2.8% CK-MM1. The release of CK-MM isoforms from muscle into plasma seems to be unrelated to the concentration of these isoforms in striated muscle.