Summary
We have investigated the residual contractile response to noradrenaline remaining after phenoxybenzamine (3×10−7 mol/l) in rabbit aorta, since it has been reported that phenoxybenzamine at low doses completely and irreversibly blocks α1- but not α2-adrenoceptors. The contraction elicited by noradrenaline slowly recovered with time after it had been almost abolished by phenoxybenzamine. This residual response was blocked by the α1-selective antagonist prazosin (3×10−8 mol/l) but not by the α2-selective antagonist rauwolscine (3×10−7 mol/l). The results confirm that the smooth muscle of rabbit aorta contains α1- not α2-adrenoceptors.
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References
Cambridge D, Davey MJ, Massingham R (1977) Prazosin, a selective antagonist of post-synaptic α-adrenoceptors. Br J Pharmacol 59:514P-515P
Constantine JW, Lebel W (1980) Complete blockade by phenoxybenzamine of α1- but not of α2-vasculars receptors in dogs and the effects of propranolol. Naunyn-Schmiedeberg's Arch Pharmacol 314: 149–156
Docherty JR, Starke K (1981) An examination of postsynaptic α-adrenoceptor subtypes in rabbit blood vesels and rat anococcygeus muscle in vitro. J Cardiovasc Pharmacol (in press)
Doxey JC, Smith CFC, Walker JM (1977) Selectivity of blocking agents for pre-and postsynaptic α-adrenoceptors. Br J Pharmacol 60:91–96
Dubocovich ML, Langer SZ (1974) Negative feed-back regulation of noradrenaline release by nerve stimulation in the perfused cat's spleen: differences in potency of phenoxybenzamine in blocking the pre-and post-synaptic adrenergic receptors. J Physiol (Lond) 237: 505–519
Furchgott RF (1954) Dibenamine blockade in strips of rabbit aorta and its use in differentiating receptors. J Pharmacol Exp Ther 111:265–284
Olivares GJ, Smith NT, Aronow L (1967) Effect of propranolol on alpha-adrenergic blockade in the dog and isolated rabbit aortic strip. Br J Pharmacol 30:240–250
Weitzell R, Tanaka T, Starke K (1979) Pre-and postsynaptic effects of yohimbine stereoisomers on noradrenergic transmission in the pulmonary artery of the rabbit. Naunyn-Schmiedeberg's Arch Pharmacol 308:127–136
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Docherty, J.R., Constantine, J.W. & Starke, K. Smooth muscle of rabbit aorta contains α1- but not α2-Adrenoceptors. Naunyn-Schmiedeberg's Arch. Pharmacol. 317, 5–7 (1981). https://doi.org/10.1007/BF00506248
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DOI: https://doi.org/10.1007/BF00506248