Influence of histamine on the bradykinin response of canine testicular polymodal receptors in vitro.

Effects of histamine on the testicular polymodal receptors were studied in vitro using canine testis-spermatic nerve preparations. Histamine induced distinct increase in the discharge rate in 6 out of 17 units tested (high responders), while it only weakly excited the remaining 11 units (low responders). The bradykinin response of low responders tended to be slightly facilitated by pretreatment with histamine, while that of high responders tended to be suppressed. Significant correlation was observed between the magnitude of histamine-induced discharges and the magnitude of change in the bradykinin responses.