Human umbilical vein vasoconstriction induced by epinephrine acting on alpha1B-adrenoceptor subtype.
OBJECTIVE
Our purpose was to determine the presence of alpha(1)-adrenoceptor messenger RNA subtypes and extend the pharmacologic characterization of alpha(1)-adrenoceptors involved in human umbilical vein (HUV) contraction.


METHODS
Cords (n=124) from healthy patients after term vaginal or cesarean deliveries were used. The vein was carefully dissected out of cords and used for reverse transcription combined with polymerase chain reaction (RT-PCR) to amplify alpha(1)-adrenoceptor transcripts. In isolated organ baths, HUV rings were mounted and cumulative concentration-response curves were constructed either for epinephrine or the selective alpha(1A)-adrenoceptor agonist, A-61603. In other series of experiments, the effects of the selective alpha(1A)- and alpha(1B)-adrenoceptor antagonists (RS-100329 or B8805-033 or spiperone, AH11110A and cyclazosin, respectively) were evaluated to estimate its blocking potencies on epinephrine concentration-response curves.


RESULTS
By means of RT-PCR technique alpha(1a)- and alpha(1b)-adrenoceptor transcripts were detected in the HUV. The blocking potency values of RS-100329 or B8805-033 against responses mediated by epinephrine were not consistent with the activation of an alpha(1A)-adrenoceptor population. Moreover, the low potency of the agonist A-61603 was not in accordance with an alpha(1A)-adrenoceptor interaction. On the other hand, the antagonist potencies of spiperone, AH11110A and cyclazosin were in agreement with an interaction on alpha(1B)-adrenoceptor subtype.


CONCLUSIONS
Although alpha(1a)- and alpha(1b)-adrenoceptor messenger RNAs are detected in the HUV, only alpha(1B)-adrenoceptors are involved in epinephrine vasoconstrictor action.
Errasti
Andrea E
AE
Department of Pharmacology, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Piso 9, 1121 Buenos Aires, Argentina.
Werneck de Avellar
Maria C
MC
Daray
Federico M
FM
Tramontano
Julián
J
Luciani
Laura I
LI
Lina Bard
Mara J
MJ
Maróstica
Elizabeth
E
Rothlin
Rodolfo Pedro
RP
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D012333:RNA, Messenger / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014471:Umbilical Veins / Q000187:drug effects* / Q000502:physiology*; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology*
C547716:ADRA1B protein, human; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D014662:Vasoconstrictor Agents; D004837:Epinephrine