Theophylline Does Not Affect Morphine Inhibition of the Isolated Vas Deferens

Abstract

Adenosine and morphine both produced an inhibition of the electrically‐evoked twitch of the isolated superfused vas deferens of the mouse. Theophylline, 10 or 100 μm, reduced the inhibitory action of adenosine but did not change inhibition by morphine. It is suggested that adenosine release is not a necessary prerequisite for morphine inhibition of transmitter release. It is also suggested that the involvement of adenosine may follow activation only of opiate μ‐receptors.