Autoradiographic localization and function of beta-adrenoceptors on the human internal mammary artery and saphenous vein.
1. Receptor autoradiography with (-)-[125I]-cyanopindolol (CYP) was used to study the distribution of beta 1- and beta 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 [125I]-CYP labelled sections, showed a high density of beta 2-adrenoceptors localized to the endothelium of the internal mammary artery and fewer beta 2-adrenoceptors on the smooth muscle. 3. The function of beta-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 [125I]-CYP binding to the saphenous vein, from X-ray film and nuclear emulsion coated coverslips, showed localization of beta 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 beta 2-adrenoceptors located on the smooth muscle. Endothelial beta 2-adrenoceptors, although present on the internal mammary artery, mediate other functions.
Molenaar
P
P
Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia.
Malta
E
E
Jones
C R
CR
Buxton
B F
BF
Summers
R J
RJ
D000368:Aged; D001345:Autoradiography; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects / Q000378:metabolism; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000033:anatomy & histology / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D010869:Pindolol / Q000031:analogs & derivatives; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012501:Saphenous Vein / Q000187:drug effects / Q000378:metabolism
D007457:Iodine Radioisotopes; D011943:Receptors, Adrenergic, beta; D010656:Phenylephrine; D020120:Iodocyanopindolol; D010869:Pindolol; D007545:Isoproterenol