Effects of prostaglandins and other putative chemical intermediaries on the activity of canine testicular polymodal receptors studied in vitro.
An in vitro testis-superior spermatic nerve preparation was used to evaluate the effects of chemical agents applied in the bathing solution. Both directly evoked discharges and responses to algesic solutions [bradykinin (BK) 9 X 10(-8) M, hypertonic saline 616 mM and high K+ solution 60 mM] of polymodal receptors were studied. Prostaglandin (PG)-E2 (1.4 X 10(-6)-1.4 X 10(-5) M) and serotonin (5-HT) (1.1 X 10(-6) to 1.4 X 10(-4) M) had only a weak excitatory effect. However, test responses to algesic substances were regularly greatly increased by PG-E2, -I2 and 5-HT. Concentrations of PG-E2 of 1.4 X 10(-8) M or greater augmented BK responses; higher concentrations and/or longer applications were needed to enhance responses to algesic salt solutions. Effective concentrations for the PGs and 5-HT were near those reported for inflamed tissues and exudate. Aspirin (ASA) (5.5 X 10(-4) M or greater, for more than 4 min) suppressed the responses to BK but not those evoked by hypertonic saline. The ASA effect on the BK response was largely restored by an addition of PG-E2. Substance P also had a weak excitatory effect on some polymodal receptors, but no significant enhancement of the response to BK was noted. These results further support a role of polymodal receptors in transmitting nociceptive information, of inflammatory origin.
D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D015232:Dinoprostone; D004285:Dogs; D011464:Epoprostenol / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism*; D011453:Prostaglandins / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D013737:Testis / Q000187:drug effects*
D011453:Prostaglandins; D011458:Prostaglandins E; D012462:Saline Solution, Hypertonic; D012701:Serotonin; D013373:Substance P; D011464:Epoprostenol; D015232:Dinoprostone; D001241:Aspirin; D001920:Bradykinin