Differential effects of BQ-123 against endothelin-1 and endothelin-3 on the rat vas deferens: evidence for an atypical endothelin receptor. |
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Authors: | A. Eglezos P. Cucchi R. Patacchini L. Quartara C. A. Maggi J. Mizrahi |
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Affiliation: | Pharmacology Department, Laboratori Guidotti S.p.A, Pisa, Italy. |
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Abstract: | 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. |
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