The inhibitory material in extracts from the bovine retractor penis muscle is not an adenine nucleotide.

Methods are described for the removal of adenosine or purine nucleotides from extracts of bovine retractor penis muscle (BRP). These methods did not interfere with the biological test preparations. Removal of adenosine and purine nucleotides by these methods did not modify the inhibitory action of the extract on the BRP. The effect of the extract on the BRP resembles that of inhibitory nerve stimulation. If the inhibitory substance present in the extract is the inhibitory transmitter, then the results indicate that, in this tissue, the transmitter is neither adenosine nor a purine nucleotide.