Adenylic deaminase activity in B1-avitaminosis and in starvation

Abstract

Muscle tissue of animals in vit. B1 deficiency shows a diminution of the activity of adenylic deaminase. This is especially marked in pigeon breast muscle, less so in rat leg muscle. Differences between these animals in the absolute levels of their deaminase activities may be largely due to ionic inhibition effects. Rat heart muscle deaminates adenylic acid indirectly. The latter is first dephosphorylated, and then NH3 formation is caused by action of adenosine deaminase. No difference occurs in rate of NH3 liberation between normal and deficient heart muscles. Decrease in the adenylic deaminase activity is accompanied by some increase in phosphorylase activity in the deficient muscle. Paired feeding expts. with inanition unaccompanied by vit. Bi deficiency show that the diminution of deaminase activity is primarily connected with the starvation, and only secondarily with vit. deficiency. The return to normal is slow, requires normal food intake and cannot be brought about by vit. B1 alone. Bradycardia gives place rapidly to normal heart rate as a result of adm. of B1 alone. It seems unlikely that the bradycardia is due to accumulation of adenylic acid following the decreased deaminase activity.