Characterization of beta adrenoceptors on cultured endothelial cells by radioligand binding.

The properties of beta-adrenoceptors present on the cultured bovine pulmonary artery endothelial cells were studied by radioligand binding. These cell contain a high density of beta-adrenoceptors (approximately 16,000 receptors/cell) having high affinity (Kd 18 pM) for 125I-iodocyanopindolol (ICYP). Competition binding experiments suggested the presence of more than two subtype of beta-adrenoceptors. 25% of the total population of receptors was found to be of beta 1-type. The remaining 75% represented a mixed population containing what is suggested to be a mixture of beta 2- and atypical beta-adrenoceptors.