AUGMENTING EFFECTS OF CYCLIC-AMP ON THE HEAT RESPONSE OF CANINE TESTICULAR POLYMODAL RECEPTORS

It has long been thought that the augmenting effects of E series prostaglandins (PG) are mediated by cyclic AMP (cAMP). In clarifying the validity of this hypothesis, we studied the effects of increases in intracellular cAMP on the heat response of testicular polymodal receptors. Recordings were obtained from testis-spermatic nerve preparations excised from dogs anesthetized with pentobarbital (30 mg/kg, i.v.). Induction of increases in intracellular cAMP by either forskolin, an adenylyl cyclase activator, or a mixture of dibutyryl cAMP (10(-4) M) and 3-isobutyl-1-methyl xanthine (10(-4) M) significantly and reversibly augmented the beat response. These results support the notion that cAMP is involved in the augmenting effect of PG E2 on the heat response of nociceptors.