Effect of JTH-601, a putative α1L-adrenoceptor antagonist, on guinea pig nasal mucosa vasculature

The existence of alpha (1)-adrenoceptors with low affinity for prazosin, an alpha (1L) subtype, has been proposed in addition to alpha (1)-adrenoceptor subtypes with high affinity for prazosin, i.e. the alpha (1H) group: alpha (1A), alpha (1B) and alpha (1D) subtypes. In the present study, we investigated the effect of JTH-601 (3-( N-[2-(4-hydroxy-2-isopropyl-5-methylphenoxy)ethyl]-N-methylaminomethyl)-4-methoxy-2,5,6-trimethylphenol hemifumarate), a putative alpha (1L)-adrenoceptor antagonist, on the isolated guinea pig nasal mucosa vasculature. JTH-601 (0.01-0.03 muM) competitively antagonized the noradrenaline-induced contraction of the tissue in a concentration-dependent manner. The pA(2) value for JTH-601 was 8.14 +/- 0.04 (means +/- SEM, n = 6). The data suggests that the alpha (1L)-subtype is involved in the noradrenaline-induced contraction of the guinea pig nasal mucosa vasculature. (C) 2001 Elsevier Science B.V. All rights reserved.