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Postjunctional α 2 ‐adrenoceptors mediate vasoconstriction in human subcutaneous resistance vessels
Author(s) -
Nielsen H.,
Thom S.McG.,
Hughes A.D.,
Martin G.N.,
Mulvany M.J.,
Sever P.S.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12022.x
Subject(s) - myograph , vasoconstriction , yohimbine , medicine , vascular resistance , endocrinology , anatomy , antagonist , chemistry , vasodilation , receptor , hemodynamics
1 In vitro studies have been performed on human medium‐sized muscular arteries (internal diameter 1–4 mm) in a classical organ bath and with human subcutaneous resistance arteries (internal diameter 103–626 μ m ) in a microvascular myograph. 2 Although the medium‐sized muscular arteries showed no response to either of the α 2 ‐agonists B‐HT 933 or UK 14304 in concentrations up to 10 μ m , the subcutaneous resistance arteries from all regions examined showed well‐pronounced and concentration‐dependent responses to B‐HT 933, the pD 2 (‐log EC 50 ) being 5.11 ± 0.09. 3 In the resistance arteries the α 2 ‐antagonist yohimbine caused a parallel shift to the right of the B‐HT 933 concentration‐response curve; the yohimbine pA 2 for the B‐HT 933 receptor was 7.86 ± 0.12. 4 There was an inverse relationship between the maximum response to B‐HT 933 and the calibre of the resistance vessels. 5 These results indicate the presence of a postjunctional α 2 ‐adrenoceptor in human subcutaneous resistance arteries and not in medium sized muscular arteries.