A 61603 hydrobromide is a potent and selective agonist of α1A-adrenoceptor [1].
α1A-adrenoceptor (α1A-AR) belongs to α1- adrenergic receptors, which include three subtypes α1A, α1B and α1D and play an important role in regulating cell growth and proliferation.
A 61603 hydrobromide is a potent and selective α1A-adrenoceptor agonist. A-61603 was 35-fold more potent at α1A-AR than at α1B-AR or α1D-AR. In fibroblast cells transfected with α1A-AR, A-61603 significantly stimulated phosphoinositide hydrolysis [1]. A 61603 exhibited affinity for α1A-AR, α1B-AR and α1D-AR with pKi values of 8.05/7.52, 5.68 and 5.87, respectively. Also, A 61603 exhibited agonist activities for α1A-AR, α1B-AR and α1D-AR with pEC50 values of 8.24/7.66, 6.50 and 5.59, respectively [2]. In neonatal rat ventricular myocytes, A61603 significantly increased the frequency of Ca2+ transients with EC50 value of 6.9 nM in a dose-dependent way [3]. In mesenteric vascular bed isolated from mice, A61603 significantly increased perfusion pressure with 235-fold higher potency than phenylephrine, which suggested that α1A-AR plays an important role in the control of blood pressure [4].
References:
[1]. Knepper SM, Buckner SA, Brune ME, et al. A-61603, a potent alpha 1-adrenergic receptor agonist, selective for the alpha 1A receptor subtype. J Pharmacol Exp Ther, 1995, 274(1): 97-103.
[2]. Meyer MD, Altenbach RJ, Hancock AA, et al. Synthesis and in vitro characterization of N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8- tetrahydronaphthalen-1-yl]methanesulfonamide and its enantiomers: a novel selective alpha 1A receptor agonist. J Med Chem, 1996, 39(20): 4116-4119.
[3]. Luo DL, Gao J, Fan LL, et al. Receptor subtype involved in alpha 1-adrenergic receptor-mediated Ca2+ signaling in cardiomyocytes. Acta Pharmacol Sin, 2007, 28(7): 968-974.
[4]. Martínez-Salas SG1, Campos-Peralta JM, Pares-Hipolito J, et al. Alpha1A-adrenoceptors predominate in the control of blood pressure in mouse mesenteric vascular bed. Auton Autacoid Pharmacol, 2007, 27(3): 137-142.