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Autoradiographic localization and function of β‐adrenoceptors on the human internal mammary artery and saphenous vein
Author(s) -
Molenaar P.,
Malta E.,
Jones C.R.,
Buxton B.F.,
Summers R.J.
Publication year - 1988
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.1476-5381.1988.tb16568.x
Subject(s) - isoprenaline , phenylephrine , vein , artery , endothelium , medicine , vascular smooth muscle , endocrinology , beta adrenoceptor , adrenergic receptor , anatomy , biology , chemistry , smooth muscle , receptor , stimulation , blood pressure
1 Receptor autoradiography with (−)‐[ 125 I]‐cyanopindolol (CYP) was used to study the distribution of β 1 and β 2 ‐adrenoceptor subtypes in the human internal mammary artery and saphenous vein. 2 Images from X‐ray film and nuclear emulsion coated coverslips, exposed to [ 125 I]‐CYP labelled sections, showed a high density of β 2 ‐adrenoceptors localized to the endothelium of the internal mammary artery and fewer β 2 ‐adrenoceptors on the smooth muscle. 3 The function of β‐adrenoceptors in ring preparations of the internal mammary artery was investigated in organ bath studies. (−)‐Isoprenaline produced concentration‐dependent relaxation of phenylephrine contracted rings. The potency and maximal effects of (−)‐isoprenaline were not influenced by the presence of the endothelium. 4 Images of [ 125 I]‐CYP binding to the saphenous vein, from X‐ray film and nuclear emulsion coated coverslips, showed localization of β 2 ‐adrenoceptors to the outer smooth muscle and not to the endothelium. 5 Relaxation of mammary artery and saphenous vein to (−)‐isoprenaline is mediated via β 2 ‐adrenoceptors located on the smooth muscle. Endothelial β 2 ‐adrenoceptors, although present on the internal mammary artery, mediate other functions.