Contractile and binding activities of structural analogues of LTC4 in the longitudinal muscle of guinea-pig ileum.
High affinity binding sites for LTC4 have been identified in various tissues, including guinea-pig ileal longitudinal muscle. More recently, it has been shown that LTC4 binds to non-receptor sites as well, particularly to glutathione transferases. In the present study, LTC4 and 9 chemically synthesized analogues, as well as the SRS-A antagonist FPL 55712 and S-decyl-glutathione, were tested for their ability to inhibit 3H-LTC4 binding in membranes from guinea-pig ileal longitudinal muscle and to affect the tone of the ileum in vitro. A significant correlation between binding and contractile activities was found for the LTC4 analogues and FPL 55712. However, S-decyl-glutathione, although possessing some affinity for LTC4 binding sites, was devoid of any effect on guinea-pig ileum tone at least up to 10(-5) M, thus indicating that these sites cannot be functional receptors, although they may represent other units involved in leukotriene action, e.g. uptake sites.
Sala
A
A
Institute of Pharmacological Sciences, University of Milan, Italy.
Civelli
M
M
Oliva
D
D
Spur
B
B
Crea
A E
AE
Folco
G C
GC
Nicosia
S
S
D000818:Animals; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology*; D008297:Male; D015394:Molecular Structure; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000502:physiology*; D013189:SRS-A / Q000378:metabolism* / Q000494:pharmacology
D013189:SRS-A