Enkephalin inhibits presynaptically the contractility of urinary tract smooth muscle.
The influence of methionine-enkephalin and leucine-enkephalin on human detrusor and on pig detrusor, trigone, bladder neck and urethral smooth muscle was investigated in vitro. The enkephalins inhibited the smooth muscle contractility presynaptically. Methionine-enkephalin was about 40% more potent than leucine-enkephalin. Phentolamine-resistant contractions were less inhibited by the enkephalins than atropine-resistant contractions and contractions that were not blocked. The inhibitory nerve responses of the trigone, bladder neck and urethra were unaffected.
D000818:Animals; D003864:Depression, Chemical; D004743:Enkephalin, Leucine / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D013552:Swine; D014551:Urinary Tract / Q000187:drug effects*
D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine