[Physiology and physiopathology of ryanodine receptors in swine. Significance of sensitivity to stress, stress myopathies, malignant hyperthermia and meat quality].

During the last decades intensive breeding of pigs has improved the growth rate, food conversion and the ratio between meat and fat. However, this improvement is very often associated in certain breeds of pig with the porcine stress syndrome, a higher incidence of muscle diseases and a reduced meat quality referred to as pale, soft exudative pork (PSE). These problems are well known since decades and are obviously caused by a variety of factors. The discovery of a mutation in the ryanodine receptor or Ca-release channel in the striated muscles of affected pigs has concentrated research on the function of this protein. The mutation of the ryanodine receptor or Ca-release channel may account for the problems mentioned above because the changed ryanodine receptor can be activated much easier and there is no doubt that the inactivation is delayed or-under some circumstances-even impossible. Consequently, the cytosolic Ca concentration in skeletal muscle cells will increase and induce uncontrolled muscle activity. The recommendation is given to breed out this mutation for elimination of a major reason of the porcine stress syndrome and PSE.