RT Journal Article
SR Electronic
T1 Coexistence of beta-1 and beta-2 adrenergic receptors in the human heart: effects of treatment with receptor antagonists or calcium entry blockers.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 561
OP 568
VO 234
IS 3
A1 A Hedberg
A1 F Kempf, Jr
A1 M E Josephson
A1 P B Molinoff
YR 1985
UL http://jpet.aspetjournals.org/content/234/3/561.abstract
AB The properties of the binding of [125I]iodopindolol ([125I]IPIN) to beta adrenergic receptors on plasma membranes prepared from right atrial tissue removed during cardiac bypass surgery were investigated. Some of the patients from whom the tissue was removed had been treated before surgery with either a beta adrenergic receptor antagonist or a calcium entry blocker or both. The specific binding of [125I]IPIN to beta adrenergic receptors was saturable, stereoselective and rapidly reversible. Studies of the inhibition of the specific binding of [125I]IPIN by drugs selective for beta-1 or beta-2 adrenergic receptors suggested that both beta-1 and beta-2 adrenergic receptors are present in the tissue, with approximately 55% of the receptors having the properties of beta-2 adrenergic receptors. The density of receptors in patients not treated with beta adrenergic receptor antagonists or calcium entry blockers was approximately 80 fmol/mg of protein, whereas the density of beta adrenergic receptors in treated patients was increased by approximately 50%. The relative proportion of beta-1 to beta-2 adrenergic receptors in subjects treated with beta adrenergic receptor antagonists and/or calcium entry blockers was not significantly different from that in untreated subjects. Studies were also carried out with a limited number of samples of human ventricular muscle obtained from untreated subjects at the time of surgery. The density of receptors was lower than that observed in studies with atrial tissue. However, as with atrial tissue, approximately half of the receptors appeared to be beta-2 adrenergic receptors.