Demonstration of alpha 1-adrenoceptors in rat nasal mucosa.
3H-Prazosin was used to demonstrate alpha 1-adrenoceptors in rat nasal mucosa. Specific binding is saturable and occurs to a homogeneous class of binding sites with high affinity (Kd = 0.07 +/- 0.01 nmol/l and with a receptor density of 0.36 +/- 0.02 pmol/g tissue or 14 +/- 1 fmol/mg protein. Kinetic experiments resulted in a Kd-value of 0.03 nmol/l. The binding is stereoselectively inhibited by epinephrine enantiomers. The antagonist prazosin inhibits 3H-Prazosin binding with high affinity, in contrast to yohimbine, classifying the binding sites as alpha 1-adrenoceptors. Inhibition experiments with WB4101 indicated the presence of alpha 1a- (31 +/- 9%) and alpha 1b-adrenoceptor subtypes in the rat nasal mucosa. The order of potencies of agonists determined in competition experiments was (-)epinephrine greater than (+)epinephrine greater than (-)phenylephrine.
van Megen
Y J
YJ
Department of Otorhinolaryngology, St. Radboud Hospital, Nijmegen, The Netherlands.
Klaassen
A B
AB
Rodrigues de Miranda
J F
JF
Wentges
R T
RT
van Ginneken
C A
CA
D000317:Adrenergic alpha-Antagonists; D000818:Animals; D001667:Binding, Competitive; D004146:Dioxanes; D009297:Nasal Mucosa / Q000032:analysis*; D011224:Prazosin; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D011942:Receptors, Adrenergic, alpha; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D011224:Prazosin