Adaptation to thermal stress in the freshwater eurythermal teleostSarotherodon mossambicus: Lactate dehydrogenase activity
LDH activity decreased in the osmoregulatory organs and increased in the non-osmoregulatory organs from the small and large individuals ofS. mossambicus on adaptation to both cold and warm temperatures, relative to normals at room temperature. In any size group, the activity was generally higher in the brain and white muscle, lower in the gill and intermediate in the liver, red muscle, kidney and intestine. The enzyme activity was size-dependent, irrespective of adaptation temperature it was higher in the organs from the large individuals than in those from the small ones. However, the variations in the % LDH activity in the organs between the small and large individuals were very slight in magnitude and inconsistent in direction. The metabolic efficiency to adapt to thermal stress decreases with size.