RT Journal Article
SR Electronic
T1 (-)-2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin (N-0923), a selective D2 dopamine receptor agonist demonstrates the presence of D2 dopamine receptors in the mouse vas deferens but not in the rat vas deferens.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 1342
OP 1348
VO 267
IS 3
A1 P L Martin
A1 M Kelly
A1 N J Cusack
YR 1993
UL http://jpet.aspetjournals.org/content/267/3/1342.abstract
AB Experiments were carried out using the D2 dopamine receptor-selective agonist (-)-2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin (N-0923) in the rat and the mouse isolated vas deferens to determine whether these tissues contained inhibitory D2 receptors in addition to their inhibitory alpha-2 adrenoceptors. In the mouse vas deferens N-0923 and the alpha-2 adrenoceptor agonist clonidine inhibited the electrically evoked twitch responses. The actions of clonidine, but not of N-0923, were antagonized by the alpha-2 antagonist idazoxan (pKb = 7.9), and responses to N-0923 were antagonized by the D2 antagonist sulpiride (pKb = 8.1). In the rat vas deferens, clonidine, but not N-0923, inhibited the twitch responses and these inhibitions were antagonized by idazoxan (pKb = 7.9) but not by sulpiride. Other D2 receptor agonists were tested in the mouse and in the rat vas deferens for their ability to activate D2 and alpha-2 receptors, respectively. At the D2 receptors in the mouse vas deferens (alpha-2 blocked) the potency order was (+)-propyl-9-hydroxy-naphtoxazine > pergolide > N-0923 = apomorphine > bromocriptine > quinpirole > dopamine. At the alpha-2 receptors in the rat vas deferens the potency order was pergolide > bromocriptine > (+)-propyl-9-hydroxynapthoxazine > apomorphine > quinpirole > or = dopamine. N-0923 was inactive but antagonized the responses to clonidine. N-0923 was therefore the most D2 receptor selective agonist tested.(ABSTRACT TRUNCATED AT 250 WORDS)