α1- and α2-adrenoceptor subtypes: Selectively of various agonists and relative distribution of receptors as determined in rats

摘要: In β-blocked pithed rats various α-adrenoceptor agonists increased mean blood pressure. Dose-response curves were determined for the in absence and presence of two selective antagonists, rauwolscine (α2) prazosin (α1). Doses these antagonists which shifted dose response an agonist 10-fold to right along abscissa D10 = D10R; D10P) then calculated. The ratio D10R/D10P varied greatly within 10 drugs tested is concentrated as a measure agonist's selectivity α1/α2. B-HT 920 (most α2) methoxamine α1) nictitating membrane dose-dependently. yohimbine cumulative dose-response different extents, indicating α-receptor populations, similar those at postsynaptic vascular sites. any given tissue, equieffective doses, 920/methoxamine, considered α1/α2 adrenoceptor ‘importance’ that tissue. This was high (4.0) compared with sites (0.8) presynaptic cardiac (0.04). It concluded effect will depend on (1) its selectively (2) adrenoceptors target organ.