TY - JOUR
T1 - α-Methylnoradrenaline-induced contractions in rat aorta are mediated via α(1D)-adrenoceptors
AU - Castillo, E. F.
AU - Valencia, I.
AU - Bobadilla, R. M.
AU - Villalon, C. M.
AU - Castillo, C.
PY - 1997
Y1 - 1997
N2 - The subtype(s) of α-adrenoceptor-mediating contractions to α-methynoradrenaline in the rat aorta has been investigated by using α-adrenoceptor-selective competitive antagonists and the α1-adrenoceptor selective agonist, phenylephrine, for comparison. α-Methylnoradrenaline and phenylephrine elicited concentration-dependent contractions in the endothelium-denuded and endothelium-intact aortic rings with similar ar potencies and maximal effects. α-Methylnoradrenaline- and phenylephrine-induced contractions in endothelium-denuded aortic rings were competitively antagonized by prazosin (pA2 = 9.38 and 9.13; respectively) and rauwolscine (pA2 = 7.19 and 6.60, respectively). This confirms that there is an α1- and a non α2-adrenoceptor response to α-methylnoradrenaline in the rat aorta. The subtype selective α(1D)-adrenoceptor antagonist, BMY 7378, was found to antagonize contractions to α-methylnoradrenaline and phenylephrine competitively in endothelium-denuded and endothelium-intact aortic rings. The pA2 values of BMY 7378 against α-methylnoradrenaline (8.39 and 8.41; endothelium-intact and endothelium-denuded, respectively) and phenylephrine (8.64 and 8.76; endothelium-intact and endothelium-denuded, respectively), are consistent with its published functional potency and clonal α(1D)-adrenoceptor binding affinity. In addition, contractions to α-methylnoradrenaline and phenylephrine in endothelium-denuded aortic rings, were potently inhibited by WB 4101 with pA2 values of 9.75 and 9.25, respectively. The high pA2 values for WB 4101 indicate that the α(1B)-adrenoceptor subtype does not seem to participate in α-methylnoradrenaline (and phenylephrine) induced contractions in this artery. These results suggest that the α(1D)-subtype plays a determining role in rat aorta contractions induced by α-methylnoradrenaline.
AB - The subtype(s) of α-adrenoceptor-mediating contractions to α-methynoradrenaline in the rat aorta has been investigated by using α-adrenoceptor-selective competitive antagonists and the α1-adrenoceptor selective agonist, phenylephrine, for comparison. α-Methylnoradrenaline and phenylephrine elicited concentration-dependent contractions in the endothelium-denuded and endothelium-intact aortic rings with similar ar potencies and maximal effects. α-Methylnoradrenaline- and phenylephrine-induced contractions in endothelium-denuded aortic rings were competitively antagonized by prazosin (pA2 = 9.38 and 9.13; respectively) and rauwolscine (pA2 = 7.19 and 6.60, respectively). This confirms that there is an α1- and a non α2-adrenoceptor response to α-methylnoradrenaline in the rat aorta. The subtype selective α(1D)-adrenoceptor antagonist, BMY 7378, was found to antagonize contractions to α-methylnoradrenaline and phenylephrine competitively in endothelium-denuded and endothelium-intact aortic rings. The pA2 values of BMY 7378 against α-methylnoradrenaline (8.39 and 8.41; endothelium-intact and endothelium-denuded, respectively) and phenylephrine (8.64 and 8.76; endothelium-intact and endothelium-denuded, respectively), are consistent with its published functional potency and clonal α(1D)-adrenoceptor binding affinity. In addition, contractions to α-methylnoradrenaline and phenylephrine in endothelium-denuded aortic rings, were potently inhibited by WB 4101 with pA2 values of 9.75 and 9.25, respectively. The high pA2 values for WB 4101 indicate that the α(1B)-adrenoceptor subtype does not seem to participate in α-methylnoradrenaline (and phenylephrine) induced contractions in this artery. These results suggest that the α(1D)-subtype plays a determining role in rat aorta contractions induced by α-methylnoradrenaline.
KW - Rat aorta
KW - α(1D)-adrenoceptors
KW - α-methylnoradrenaline
UR - http://www.scopus.com/inward/record.url?scp=0030811166&partnerID=8YFLogxK
U2 - 10.1111/j.1472-8206.1997.tb00847.x
DO - 10.1111/j.1472-8206.1997.tb00847.x
M3 - Artículo
SN - 0767-3981
VL - 11
SP - 339
EP - 345
JO - Fundamental and Clinical Pharmacology
JF - Fundamental and Clinical Pharmacology
IS - 4
ER -