Beta-adrenergic receptors on canine coronary collateral vessels: characterization and function.
The present studies were performed to examine the role of beta-adrenergic receptors in modulating smooth muscle tone in mature coronary collaterals. To examine the beta-adrenergic receptor population present, radioligand binding-cover slip autoradiographic studies were performed on sections of native canine coronary vessels and sections of coronary collaterals developed after placement of Ameroid constrictors. Specific binding of the nonselective beta-adrenergic antagonist [125I]iodopindolol to vascular smooth muscle in segments of both collaterals and native coronary arteries was saturable and stereospecific. Maximal binding and the potency of beta-adrenergic subtype-selective antagonists were similar in all segments. Beta-adrenergic relaxation of native coronary vessels and collateral vessels were studied in isolated organ chambers after preconstriction with prostaglandin F2 alpha. Both native coronary arteries and collateral segments demonstrated beta-adrenergic-mediated relaxation with affinities for both agonists and antagonists compatible with a mixed population of beta 1- and beta 2-adrenergic receptors. These studies indicate that during development, the new collateral vascular smooth muscle expresses a functional population of beta-adrenergic receptors, comparable to that in native vessels.
Feldman
R D
RD
Department of Internal Medicine and Pharmacology, University of Iowa College of Medicine, Iowa City 52242.
Christy
J P
JP
Paul
S T
ST
Harrison
D G
DG
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D001345:Autoradiography; D003097:Collateral Circulation; D003331:Coronary Vessels / Q000378:metabolism*; D004285:Dogs; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011412:Propanolamines / Q000494:pharmacology; D011869:Radioligand Assay; D011943:Receptors, Adrenergic, beta / Q000378:metabolism / Q000502:physiology*
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; C026777:ICI 118551; D001262:Atenolol; C029247:3-iodopindolol; D010869:Pindolol; D007545:Isoproterenol