Differential effects of BQ-123 against endothelin-1 and endothelin-3 on the rat vas deferens: evidence for an atypical endothelin receptor.
1. Endothelin-1 and endothelin-3 enhanced concentration-dependently the rat vas deferens twitch response to electrical stimulation, endothelin-1 being three times more potent. Sarafotoxin S6c was at least 200 times less active than endothelin-1. 2. The response to endothelin was antagonized in a competitive manner by the supposedly selective ETA receptor antagonist, BQ-123 (pA2:7.0 +/- 0.1). In contrast, the endothelin-1 concentration-response curve was only shifted two fold in the presence of 10 microM BQ-123, while no effect was observed at 1 microM. 3. This evidence suggests the rat vas deferens contains an endothelin receptor not conforming to the ETA/ETB receptor subtype classification so far proposed.
Eglezos
A
A
Pharmacology Department, Laboratori Guidotti S.p.A, Pisa, Italy.
Cucchi
P
P
Patacchini
R
R
Quartara
L
L
Maggi
C A
CA
Mizrahi
J
J
D000595:Amino Acid Sequence; D000818:Animals; D004558:Electric Stimulation; D016232:Endothelins / Q000037:antagonists & inhibitors*; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017466:Receptors, Endothelin / Q000187:drug effects*; D014649:Vas Deferens / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014757:Viper Venoms / Q000494:pharmacology
D016232:Endothelins; D010456:Peptides, Cyclic; D017466:Receptors, Endothelin; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; C072247:cyclo(Trp-Asp-Pro-Val-Leu)