Characterisation of 5-HT receptors in human coronary arteries by molecular and pharmacological techniques.
5-Hydroxytryptamine (5-HT) can produce both vasoconstrictor and vasorelaxant effects in human coronary arteries and the response to 5-HT can be influenced by the presence of disease. The aim of the present study was to elucidate the 5-HT receptor subtypes responsible for mediating 5-HT-evoked contraction of human coronary arteries using pharmacological, molecular and immunocytochemical approaches. Normal human coronary arteries, with intact endothelium, were mounted in tissue baths, and the vascular responses to 5-HT and 5-HT receptor agonists were studied. The effects of 5-HT1 and 5-HT2 receptor antagonists on these responses were also studied. Expression of messenger ribonucleic acid (mRNA) encoding different 5-HT receptors in human coronary arteries, atrium, ventricle wall and epicardium was determined using reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot analysis. The expression of 5-HT1B or 5-HT1D receptor protein was studied using subtype selective antibodies and standard immunocytochemical techniques. The rank order of 5-HT receptor agonist potency in causing vasoconstriction was 5-carboxamido tryptamine, (5-CT) > zolmitriptan = BW183C91 (N10-desmethyl zolmitriptan) = alpha-methyl-5-hydroxytryptamine (alpha-CH3-5-HT) = 5-HT = sumatriptan > 2-methyl-5-hydroxytryptamine (2-CH3-5-HT) = 8-hydroxy-DPAT (8-OH-DPAT). Alpha-CH3-5-HT, 5-CT, 5-HT, zolmitriptan and BW 183C91 were significantly more potent (approximately 3-fold) than sumatriptan and 2-CH3-5-HT, which in turn were more potent than 8-OH-DPAT. Ketanserin and methiothepin (5-HT2 and 5-HT1 receptor antagonists, respectively) caused parallel rightward shifts of the concentration-effect curves to alpha-CH3-5-HT or 5-CT, respectively, without changing the maximum contractile response. In human coronary arteries, atrium. ventricle and epicardium. RT-PCR products corresponding to the human 5-HT2A, 5-HT1B and 5-HT1F receptors were expressed in high levels, mRNAs coding for 5-HT7, 5-HT1A and 5-HT1D receptors were only weakly expressed. No 5-HT1F receptor mRNA was detected. In coronary arteries there was a differential expression of 5-HT1B versus 5-HT1D receptor mRNAs, with 5-HT1B mRNAs being found in greater abundance. Dense 5-HT1B-immunoreactivity was detected on smooth muscle layer within coronary artery, however, 5-HT1D-immunoreactivity was not detected. It is concluded that 5-HT-evoked contraction of human coronary arteries is most probably mediated via the activation of both 5-HT1B and 5-HT2A receptors.
Nilsson
T
T
Department of Internal Medicine, Lund University Hospital, Sweden.
Longmore
J
J
Shaw
D
D
Pantev
E
E
Bard
J A
JA
Branchek
T
T
Edvinsson
L
L
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D002319:Cardiovascular System / Q000187:drug effects / Q000378:metabolism; D003331:Coronary Vessels / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D008719:Methiothepin / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D023303:Oxazolidinones; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D044302:Receptor, Serotonin, 5-HT1B; D044346:Receptor, Serotonin, 5-HT1D; D011985:Receptors, Serotonin / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D018170:Sumatriptan / Q000494:pharmacology; D014018:Tissue Distribution; D014363:Tryptamines; D014661:Vasoconstriction / Q000187:drug effects
C470302:HTR1B protein, human; D010080:Oxazoles; D023303:Oxazolidinones; D012333:RNA, Messenger; D044302:Receptor, Serotonin, 5-HT1B; D044346:Receptor, Serotonin, 5-HT1D; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D014363:Tryptamines; C089750:zolmitriptan; D012701:Serotonin; D008719:Methiothepin; C045918:2-methyl-5-HT; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D018170:Sumatriptan; C047087:5-carboxamidotryptamine; D007650:Ketanserin