EXCITATION AND SENSITIZATION OF THE HEAT RESPONSE INDUCED BY A PHORBOL ESTER IN CANINE VISCERAL POLYMODAL RECEPTORS STUDIED IN-VITRO

To clarify the possible involvement of protein kinase (PK) C activatio n in the excitation and sensitization of polymodal receptors (PMRs), t he effects of phorbol 12,13-dibutyrate (PDBu) on PMRs were studied in canine testis-spermatic nerve preparations in vitro. Application of PD Bu (10(-7) 10(-6), and 10(-5) M) for 5 min evoked a significant increa se in the ongoing activity of the PMRs within 15 min. PDBu (10(-8) to 10(-5) M) significantly augmented the subsequent heat responses of the PMRs. Staurosporine (10(-6) M), a PK inhibitor, attenuated the effect of PDBu on heat responses. These data suggest that activation of PKC contributes to the activities of PMRs.