Inhibition by N⁶, O^2′-Dibutyryl 3′,5′-Cyclic Adenosine Monophosphate of Phosphate Transport and Metabolism in BHK₂₁C₁₃ and BHK₂₁Py Cells Available to Purchase

Theophylline plus dibutyryl 3′,5′-cyclic adenosine monophosphate (dibutyryl cAMP) decreases the multiplication rate of both BHK₂₁C₁₃ and BHK₂₁Py cells. The level of saturation density of BHK₂₁C₁₃ cultures is diminished in the presence of theophylline plus dibutyryl cAMP. On the contrary, dibutyryl cAMP plus theophylline does not prevent BHK₂₁Py cultures from reaching the high saturation density observed in the absence of nucleotide.

Dibutyryl cAMP plus theophylline or dibutyryl cAMP alone inhibit both phosphate transport and metabolism in normal as well as in transformed cells, but the mean phosphate uptake is more inhibited in BHK₂₁C₁₃ cells than in BHK₂₁Py cells. The results agree with the hypothesis that 3′,5′-cyclic adenosine monophosphate is an intermediate in the contact inhibition of growth.