The Reduction of Radiation-induced Mitotic Delay by Caffeine: A Test of the Cyclic AMP Hypothesis

Abstract
Macroplasmodia containing synchronously-dividing nuclei were prepared from stock cultures of Physarum .pi.olycephalum. Reduction of radiation-induced mitotic delay was related to increasing concentrations of caffeine. Caffeine must be present for most or all of the post-irradiation pre-mitotic period, pre-irradiation caffeine treatment had no detectable effect. Chemicals inhibiting cyclic AMP phosphodiesterase may either increase or decrease radiation-induced mitotic delay, suggesting that AMP metabolism per se is unlikely to be the basis for the healing effect of caffeine. The role of caffeine may be complex, involving other factors such as Ca transport or protein synthesis effects.