[Antagonistic effect of tetrahydroproberberine homologues on alpha 1-adrenoceptor].
The antagonistic effect of tetrahydroproberberine (THP) homologues on alpha 1-adrenoceptor was studied by combination of radioligand binding assays and measurements of vasoconstriction responses. The results showed that l-tetrahydropalmatine (l-THP), l-stepholidine (l-SPD), THPB-18 and tetrahydroberberine (THB) competitively inhibited the 125I-BE2254 specific binding in rat cerebral cortex with pK1 values of 5.54 +/- 0.36, 5.56 +/- 0.47, 5.75 +/- 0.56 and 6.01 +/- 0.60, respectively, and the Hill efficiency was not significantly different from unity. They inhibited phenylephrine-induced constrictions with pA2 values of 5.48 +/- 0.58, 5.66 +/- 0.54, 5.64 +/- 0.34 and 5.45 +/- 0.76, respectively, and the slopes of Schild plot were not significantly different from unity. The results indicate that the 4 THP homologues are non-subtype selective competitive antagonists for alpha 1-adrenoceptor with similar affinities.
Lu
Z Z
ZZ
Institute of Vascular Medicine, Third Hospital, Beijing Medical University.
Wei
X
X
Jin
G Z
GZ
Han
Q D
QD
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001599:Berberine / Q000031:analogs & derivatives / Q000494:pharmacology; D001600:Berberine Alkaloids / Q000494:pharmacology*; D001667:Binding, Competitive; D008297:Male; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D001600:Berberine Alkaloids; D018340:Receptors, Adrenergic, alpha-1; D001599:Berberine; C010513:stepholidine; C014215:tetrahydropalmatine; C004645:canadine