Effect of JTH-601, a putative alpha(1L)-adrenoceptor antagonist, on guineapig 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)-adrenocepto r subtypes with high affinity for prazosin, i.e. the alpha (1H) group: alph a (1A), alpha (1B) and alpha (1D) subtypes. In the present study, we invest igated the effect of JTH-601 (3-( N-[2-(4-hydroxy-2-isopropyl-5-methylpheno xy)ethyl]-N-methylaminomethyl)-4-methoxy-2,5,6-trimethylphenol hemifumarate ), a putative alpha (1L)-adrenoceptor antagonist, on the isolated guinea pi g nasal mucosa vasculature. JTH-601 (0.01-0.03 muM) competitively antagoniz ed the noradrenaline-induced contraction of the tissue in a concentration-d ependent manner. The pA(2) value for JTH-601 was 8.14 +/- 0.04 (means +/- S EM, n = 6). The data suggests that the alpha (1L)-subtype is involved in th e noradrenaline-induced contraction of the guinea pig nasal mucosa vasculat ure. (C) 2001 Elsevier Science B.V. All rights reserved.