Evidence of the Existence of α_1B‐Adrenoceptors on Hepatocytes of Domestic Fowl (Gallus domesticus)

Abstract

In liver cell membranes of laying hens a,-adrenergic receptors were characterized using 'H-prazosin. Specific binding was saturable and indcative of a single class of high-affinity binding sites with a KO of 0.40 f 16 nM and a B, , , of 390 f 38 fmol/mg membrane protein. Preincubation of membranes with chlorethylclonidine significantly diminished the binding of 'H-prazosin ( B , , , = 99 f 14 frnol/mg rnernbrane protein). Furthermore, competition experiments revealed a rank order of prazosin >> phentolamine = oxymetazoline >> WB 4101, with K, values of 0.71 f 0.62,20 f 6, 32 f 13, and 119 & 48 nM, respectively. These results suggest the existence of a,,-adrenergic receptors in hen liver cell membranes.