[Effect of (-)-stepholidine on blood pressure and alpha-adrenoceptor agonists-, KCl- and CaCl2-evoked contractions of aortic strips].
Iv (-)-SPD lowered the blood pressure in anesthetized rat, the ED50 value was 5.1 +/- 2.5 mg.kg-1. In the experiments of rat and rabbit aortic strips, (-)-SPD 0.3-100.0 mumol.L-1 inhibited the contraction initiated by clonidine (alpha 2) and phenylephrine (alpha 1) and shifted the dose-response curve to the right parallely without change in maximum response. The inhibitory ratio of (-)-SPD acting on alpha 2/alpha 1 adrenergic receptors was about 7.2, and (-)-SPD thus was predominant inhibition on alpha 2 adrenergic receptors. In the experiment of aortic strips from reserpinized rabbits, the inhibition of (-)-SPD on contraction evoked by clonidine was diminished markedly. The results suggest that (-)-SPD stimulated mainly the alpha 2-adrenergic receptors of presynaptic nerve endings. Moreover (-)-SPD 1 mumol.L-1 inhibited the release of intracellular Ca2+ initiated by NE. (-)-SPD 3-30 mumol.L-1 blocked the voltage-dependent Ca2+ channel.
Shen
D L
DL
Shanghai Institute of Materia Medica, Chinese Academy of Sciences.
Jin
G Z
GZ
He
Y F
YF
Zhang
Z D
ZD
Sun
Z
Z
Lu
Y Q
YQ
Yang
Z C
ZC
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001011:Aorta / Q000187:drug effects; D001599:Berberine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002122:Calcium Chloride / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
D000959:Antihypertensive Agents; D011942:Receptors, Adrenergic, alpha; D001599:Berberine; C010513:stepholidine; D011189:Potassium Chloride; D002122:Calcium Chloride