Purinergic Receptors: Photoaffinity Analog of Adenosine Triphosphate Is a Specific Adenosine Triphosphate Antagonist

Arylazido aminopropionyl adenosine triphosphate (ANAPP3), a photoaffinity label, antagonized specifically adenine nucleotide-induced contractions of the guinea pig vas deferens. Irradiation of tissues with visible light in the presence of ANAPP3 resulted in an irreversible antagonism, which was prevented when adenosine triphosphate was present. In the absence of light, the antagonism was reversible and may have resulted from an autoinhibition phenomenon. Responses to acetylcholine, histamine, norepinephrine, and potassium chloride were not affected by ANAPP3.