... islets and liver of fetal, suckling and adult ratsWe studied the enzyme activities of two protein complexesinvolved in the respiratory chain: succinate dehydrogenase(complex II) and cytochrome ... in the c oncentrations of rat live r cyclic AMP and of serum glucose, free fatty acids, insulin, pancreatic and totalglucagoninthemanandintherat.J. Lat. Clin. Med. 82,957±967.5. Matschinsky, ... secretionof insulin. Bearing this in mind, we determined theactivities of citrate synthase (an enzyme of the Krebscycle re¯ecting the number of mitochondria [10]), succi-nate dehydrogenase and cytochrome...