Cloning of rabbit alpha(1b)-adrenoceptor and pharmacological comparison of alpha(1a)-, alpha(1b)- and alpha(1d)-adrenoceptors in rabbit.
We have isolated a cDNA clone of the rabbit alpha(1b)-adrenoceptor which has an open reading frame of 1557 nucleotides encoding a protein of 518 amino acids. The sequence shows higher identity to those of hamster, human, and rat alpha(1b)-adrenoceptors than to those of rabbit alpha(1a)- and alpha(1d)-adrenoceptors. The pharmacological binding properties of this clone expressed in Cos-7 cells showed a characteristic profile as alpha(1b)-adrenoceptor; high affinity for prazosin (pK(i)=10.3), relatively high affinity for tamsulosin (9.5) and low affinity for (-)-(R)-1-(3-hydroxypropyl)-5-[2-[[2-[2-(2,2, 2-trifluoroethoxy)phenoxy]ethyl]amino]propyl]indoline-7-carboxamid e (KMD3213) (8.5), 2-(2,6-dimethoxy-phenoxyethyl)-aminomethyl-1, 4-benzodioxane hydrochloride (WB4101) (8.7), and 8-[2-[4-(2-methoxy-phenyl)-L-piperazinyl]-8-azaspiro[4,5]decane-7, 9-dione dihydrochloride (BMY7378) (7.3). We have compared the levels of mRNA expression of three alpha(1)-adrenoceptor subtypes in rabbit tissues using the competitive reverse transcription/polymerase chain reaction (RT/PCR) assay. In most rabbit tissues except heart, alpha(1a)-adrenoceptor mRNA was expressed 10 folds more than the other two subtypes. However, binding experiments with [3H]prazosin and [3H]KMD3213 in rabbit tissues revealed a poor relationship between binding density and mRNA level. Especially, alpha(1b) binding sites were exclusively predominant in spleen, whereas the alpha(1b) subtype was minor at the mRNA level. These results indicate a high identity of structural and pharmacological profiles of three distinct alpha(1)-adrenoceptor subtypes between rabbit and other species, but there are species differences in their distribution.
Piao
H
H
Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, 910-1193, Fukui, Japan.
Taniguchi
T
T
Nakamura
S
S
Zhu
J
J
Suzuki
F
F
Mikami
D
D
Muramatsu
I
I
D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D015723:Gene Library; D006801:Humans; D007211:Indoles / Q000378:metabolism; D008969:Molecular Sequence Data; D011224:Prazosin / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D011817:Rabbits; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection / Q000235:genetics
C547713:ADRA1A protein, human; C547716:ADRA1B protein, human; C547719:ADRA1D protein, human; C547715:Adra1a protein, rat; C547718:Adra1b protein, rat; C547721:Adra1d protein, rat; D000317:Adrenergic alpha-Antagonists; D007211:Indoles; D018340:Receptors, Adrenergic, alpha-1; D011994:Recombinant Proteins; D012313:RNA; C095285:silodosin; D011224:Prazosin