Prejunctional alpha 2-adrenergic properties of S-3341 (dicyclopropylmethyl)amino-2-delta-2-oxazoline: a comparison with clonidine.
The prejunctional activities of S-3341 and clonidine have been studied in the transmural field-stimulated epididymal part of the rat vas deferens. Both S-3341 and clonidine inhibited these neuronally induced contractions. At high concentrations, these agonists induced spontaneous contractions in the preparation, which were abolished by 10(-7) M prazosin. The inhibitory effects of S-3341 and clonidine were antagonized in a competitive manner by rauwolscine and were found not to be modified in a statistically significant manner by 10(-7) M prazosin. The pA2 values of rauwolscine against S-3341 and clonidine were the same, indicating the receptors influenced by these drugs were the same also. However, the efficacy of S-3341 is lower than that of clonidine (by a factor of approximately 100). This lower efficacy of S-3341 at the prejunctional level could be linked to the lack of a sedative effect of this compound at therapeutic concentrations.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000294:innervation; D009469:Neuromuscular Junction / Q000187:drug effects*; D010080:Oxazoles / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D000077769:Rilmenidine; D014649:Vas Deferens / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D010080:Oxazoles; D015016:Yohimbine; D003000:Clonidine; D000077769:Rilmenidine; D011224:Prazosin