Expression and pharmacological characterization of alpha1-adrenoceptors in rat seminal vesicle.
In the present study, we investigated the alpha1-adrenoceptor subtypes mediating adrenaline-induced contractions of the rat seminal vesicle by using functional studies. The reverse transcription combined with polymerase chain reaction (RT-PCR) was also used to identify of alpha1-adrenoceptor mRNA subtypes. The rank order of potency of alpha1-adrenoceptor antagonists in blocking the contractile effects of adrenaline was: prazosin = WB 4101 >>> BMY 7378 > chloroethylclonidine, indicating the presence of alpha1A-adrenoceptors in the rat seminal vesicle. In the presence of nifedipine, there was a 76% reduction in the adrenaline-induced contractions. The nifedipine-insensitive component (24%) of the contractile response to adrenaline was unaffected by chloroethylclonidine. A small pool of spare alpha1-adrenoceptors for adrenaline (0.10%) was also detected. All three alpha1-adrenoceptor subtypes were amplified when RT-PCR was performed on total RNA isolated from rat seminal vesicle. In conclusion, these data indicate the presence of three alpha1-adrenoceptor mRNA subtypes, but only alpha1A-adrenoceptors are involved in the rat seminal vesicle contraction.
Silva
M A
MA
Department of Pharmacology, Universidade Federal de São Paulo-Escola Paulista de Medicina, SP, Brazil.
Megale
A
A
Avellar
M C
MC
Porto
C S
CS
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology; D010643:Phenoxybenzamine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000096:biosynthesis* / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012669:Seminal Vesicles / Q000187:drug effects / Q000378:metabolism*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers; D004146:Dioxanes; D010879:Piperazines; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D010643:Phenoxybenzamine; C051731:chlorethylclonidine; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D009543:Nifedipine; C053428:BMY 7378; D003000:Clonidine; D011224:Prazosin; D004837:Epinephrine