Alpha 1-adrenoceptor blocking properties of spiroxatrine in rat aorta.
This preliminary study has analyzed the potential ability of the 5-HT1A ligand spiroxatrine to interact with vascular alpha 1-adrenoceptors. Norepinephrine and the selective alpha 1-adrenoceptor agonist, methoxamine, elicited concentration-dependent contractions of rat aortic rings. In contrast, (+/-)-spiroxatrine (from 10(-8) to 3.1X10(-7) M) was devoid of any effect on vascular tone per se, but shifted the concentration-response curves of norepinephrine and methoxamine to the right in a concentration-dependent manner with pA2 values of 8.48 +/- 0.22 and 8.93 +/- 0.33, respectively. Endothelium removal did not significantly affect the above pA2 values of (+/-)-spiroxatrine. These data, taken in concert, support the contention that (+/-)-spiroxatrine displays alpha 1-adrenoceptor blocking properties in rat aortic rings.
Depto. de Farmacología y Toxicología, Centro de Investigación y de Estudios Avanzados del I.P.N., D.F., México.
J A
JA
Terrón
V
V
Ransanz
M
M
Ibarra
E
E
Hong
C M
CM
Villalón
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D004146:Dioxanes / Q000494:pharmacology*; D018492:Dopamine Antagonists; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013141:Spiro Compounds / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D018492:Dopamine Antagonists; D013141:Spiro Compounds; C018387:spiroxatrine; D008729:Methoxamine; D009638:Norepinephrine