Characterization of alpha-adrenoceptor subtypes in the corpus cavernosum of patients undergoing sex change surgery.
OBJECTIVE
To characterize the subtypes of alpha1- and alpha2-adrenoceptors in the human corpus cavernosum from patients undergoing sex change surgery.


METHODS
Saturation and competition radioligand binding studies were performed for characterization at the protein level. Alpha1-adrenoceptors were labeled with [3H]prazosin and [3H]tamsulosin, while alpha2-adrenoceptors were labeled with [3H]RX 821002. Alpha1-adrenoceptor subtype mRNA was additionally determined by reverse-transcriptase polymerase chain reaction and RNase protection assays.


RESULTS
Human corpus cavernosum expressed approximately 32 and approximately 22 fmol./mg. protein alpha1- and alpha2-adrenoceptors, respectively. Competition studies with the alpha1A-selective antagonists 5-methylurapidil and (+)-niguldipine and the alpha1D-selective BMY 7378 revealed a mixed alpha1A/alpha1B-adrenoceptor population with no evidence for alpha1D-adrenoceptor protein. In contrast alpha1D-adrenoceptors were readily detected at the mRNA level. Competition binding studies with the alpha2A-selective oxymetazoline and the alpha2B-selective prazosin and ARC 239 revealed a homogeneous population of alpha2A-adrenoceptors.


CONCLUSIONS
We conclude that human corpus cavernosum expresses predominantly alpha1A-, alpha1B- and alpha2A-adrenoceptor protein; additionally the alpha1D-adrenoceptor is present at the mRNA level.
Goepel
M
M
Department of Urology, University of Essen Medical School, Germany.
Krege
S
S
Price
D T
DT
Michelotti
G A
GA
Schwinn
D A
DA
Michel
M C
MC
D000317:Adrenergic alpha-Antagonists / Q000493:pharmacokinetics; D001667:Binding, Competitive; D012734:Disorders of Sex Development / Q000601:surgery; D004305:Dose-Response Relationship, Drug; D006801:Humans; D019329:Idazoxan / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D008297:Male; D010413:Penis / Q000737:chemistry* / Q000378:metabolism / Q000601:surgery; D011224:Prazosin / Q000493:pharmacokinetics; D011942:Receptors, Adrenergic, alpha / Q000032:analysis* / Q000378:metabolism; D013449:Sulfonamides / Q000493:pharmacokinetics; D000077409:Tamsulosin
D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D013449:Sulfonamides; C058525:2-methoxyidazoxan; D000077409:Tamsulosin; D011224:Prazosin; D019329:Idazoxan