Preparation and characterization of mRNAs from rat heart muscle.

RNA was prepared from rat heart muscle by a procedure using guanidium thiocyanate and centrifugation on a CsCl cushion. Analysis of the RNA by sucrose gradient centrifugation and electrophoresis shows that major part of it was long sized. Poly (A+) RNA was isolated with a yield of 35 micrograms/g. The average size of the poly (A) tail was 120 nucleotides. RNA was translated in a reticulocyte lysate and the efficiencies were compared with total liver and skeletal muscle RNA. The translational products of poly (A+) RNA were analyzed in a two dimensional gel. They show that many muscle specific proteins have been synthesized in vitro, which indicates that at least, part of the RNAs has remained intact.