Effects of leukotriene D4 on the mechanical and electrical properties of XXXX isolated trachealis.

@entity840 @entity4337 @entity15491 @entity2473 @entity2710 @entity4338
1. The effects of @entity15491 (LTD4) on mechanical and electrical activity were examined in @entity840 isolated trachealis muscle and compared with two other bronchoconstrictors, @entity2710 and @entity4337 ( @entity4338 ). 2. LTD4 elicited concentration-dependent increases in tension in trachealis muscle which were slower in time course than responses induced by either @entity2710 or @entity4338 . The maximum response to LTD4 was approximately 85% of the @entity2710 maximum. 3. At a concentration close to the EC50 for tension changes, LTD4 had no significant effect on either transmembrane potential or slow wave activity recorded in single trachealis cells. 4. At a concentration close to the EC90 for tension changes, LTD4 caused significant membrane depolarization, transiently reduced the amplitude and increased the frequency of slow wave discharge and ultimately abolished slow wave discharge. LTD4-induced depolarization was less marked, and developed more slowly, than that evoked by either @entity2710 or @entity4338 . 5. These results show that LTD4 can elicit substantial increases in tension without altering transmembrane potential and are consistent with the view that LTD4 initiates contraction mainly through potential-independent mechanisms. However, at high concentrations the depolarization evoked by LTD4 allows the possibility that potential-dependent mechanisms may contribute to the @entity2473 .
