Characteristics of analgesia induced by adenosine triphosphate.

Adenosine triphosphate (ATP) injected intravenously in mice was found to have dose-dependent analgesic activity in the hot plate and phenylquinone-induced stretching assays. ATP prolonged the hot plate latency (ED50 value of 1 (0.7-1.4) mg/kg) and inhibited phenylquinone-induced writhing (ED50 value of 0.4 (0.31-0.52) mg/kg). Low doses of ATP produced a potent antinociceptive effect without any significant depression of locomotor activity. Treatment of mice for either 4 days or 14 days with ATP did not result in development of physical dependence on or tolerance to ATP. The analgesic action of ATP was not antagonized by naloxone at 1 and 5 mg/kg. ATP analgesia was antagonized, in a dose-related fashion, by Ca++ ion injected intracerbroventricularly which may indicate that Ca++ plays a role in ATP-induced antinociception.