Experimental cardiac hypertrophy and the synthesis of poly (A) containing RNA and of myocardial proteins in the rat: the effect of digitoxin treatment.

The synthesis of poly(A) containing RNA was increased in heart of non-digitalized and digitalized rats after aortic constriction, the increase being of the same degree as that of the RNA lacking this sequence. No differences were found, either in the absence or presence of polyuridylic acid, in the incorporation of radioactivity into protein by cardiac ribosomes isolated from animals treated differently. It may be concluded, that after the constriction of the aorta the synthesis of mRNA proceeds at a similar rate as that of the bulk RNA, and that the treatment of the animals with digitoxin does not abolish the stimulus for hypertrophy.