Effect of purinergic substances on rectal temperature in mice: involvement of P1-purinoceptors.

Effect of adenosine, 2-chloroadenosine (P1-purinoceptor agonists) and adenosine triphosphate (ATP), adenosine-5'-tetraphosphate (P2-purinoceptor agonists) on body temperature was studied in mice. Adenosine (7.5-200 mg/kg) as well as 2-chloroadenosine (0.25-7.5 mg/kg) induced hypothermia in a dose-dependent manner. However, ATP or adenosine-5'-tetraphosphate did not show any effect on body temperature. Caffeine and theophylline, P1-purinoceptor antagonists, blocked the hypothermic response of adenosine and 2-chloroadenosine. Treatment with quinidine or phenoxybenzamine (non-specific P2-purinoceptor antagonists) did not modify the hypothermic response. Similarly, treatment with drugs which modify adrenergic (reserpine, propranolol, labetalol or haloperidol), serotonergic (cyproheptadine) or histaminergic functions failed to block adenosine or 2-chloroadenosine-induced hypothermia. These results demonstrated that P1-purinoceptors mediated the hypothermic response of these purines.