Calpain and calpastatin levels in different organs of the rabbit

1. The levels of Ca-independent and Ca-dependent proteolytic activity as well as the activities of calpains and calpastatin in different organs of the rabbit was examined at various developmental stages. 2. Calpain and calpastatin levels were highest in the lung and in the kidney. 3. In all organs examined except the thymus the total level of calpain was higher than that of calpastatin. 4. In the thymus the levels of calpains and calpastatin decreased markedly with age.