Alpha1A- and alpha1B-adrenoceptors are the major subtypes in human saphenous vein.
In this study we analyzed the different alpha1-adrenoceptor (AR) subtypes present in human saphenous vein (HSV) using reverse transcription polymerase chain reaction (RT-PCR), DNA-DNA hybridization analysis and functional affinities for alpha-AR antagonists. DNA-DNA hybridization analysis of RT-PCR amplification products confirmed the presence of alpha1A- and alpha1B-ARs, and low levels of alpha1D-AR in HSV. The functional results showed: (1) prazosin, the selective alpha1-AR antagonist, phentolamine, the alpha1- and alpha2-ARs antagonist, WB 4101 and 5-MU, the selective alpha1A-AR subtype antagonists were potent, competitive antagonists of noradrenaline (NA)-induced contraction (pA2 values of 11.03, 8.06, 9.02 and 8.34, respectively). (2) Alpha1-AR-induced contraction was sensitive to the alkylating effects of CEC (the alpha1B and alpha1D-AR subtypes antagonist) and (3) The selective alpha1D-AR subtype antagonist BMY displayed low affinity (pA2 values of 6.44). This indicates that the contractile response of the HSV to alpha1-AR-induced is predominantly mediated by both alpha1A and alpha1B-AR subtypes. This was also supported by the good relationship between pA2 values from the present study and reported binding affinities (pKi) values of various alpha1-AR subtype antagonists with cloned human alpha1A- and alpha1B-AR subtypes (r=0.89 and r=0.98, respectively), but not the alpha1D-AR subtype (r=0.67). Our results indicate that alpha1A- and alpha1B-ARs are the main functional and expressed receptor subtypes in HSV.
Department of Cardiology, Box Hill Hospital, Australia. Yanm10@hotmail.com
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D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009638:Norepinephrine / Q000494:pharmacology; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012501:Saphenous Vein / Q000737:chemistry* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D018340:Receptors, Adrenergic, alpha-1; D009638:Norepinephrine