[Uptake of cyclic guanosine-3',5'-monophosphate and its metabolism in 3T6 cells].

Uptake of 3H-cGMP by cultured murine 3T6 cells was studied. The cells were shown to contain radioactivity 1 minute after its addition, with the level of radioactivity increasing during a 3 hour incubation period. By this time, the intracellular non-metabolized cGMP corresponded to 1-5% of the whole intracellular radioactivity. In the presence of theophylline the uptake of 3H-cGMP by cells was seen decreasing, however, the portion of non-metabolized cGMP reached 45-50% of the whole intracellular radioactivity. Thus, the presence of theophylline made it possible to maintain the high level of intracellular cGMP. It is concluded that the incubation of cell cultures in the medium with cGMP may be useful for achieving an elevating intracellular cGMP concentration and for studying the biological effect of cyclic nucleotide.