Polyinosinic Acid ⋅ Polycytidylic Acid: Inhibition of DNA Synthesis Stimulated by Isoproterenol

Polyinosinic acid * polycytidylic acid (poly I * poly C) inhibits isoproterenol-stimulated DNA synthesis in salivary glands of mice. A single intraperitoneal injection of 250 micrograms of poly I * poly C inhibits the stimulation of DNA synthesis when given 10 minutes before isoproterenol or at any time during the 20-hour lag period between the injection of isoproterenol and the subsequent DNA synthesis. The inhibition caused by poly I * poly C is not due to a generalized toxic action but seems to be exerted through a relatively selective mechanism. Polyuridylic acid and diethylaminoethyl dextran are less effective in inhibiting isoproterenol-stimulated DNA synthesis.