Heterogeneity of beta-adrenoreceptors in guinea pig alveolar type II cells.
[3H]Dihydroalprenolol ([3H]DHA) binding to guinea pig alveolar type II cell membrane revealed the presence of both high (KD = 0.38 nM) and low (KD = 4.2 nM) affinity beta-adrenoreceptors. The low affinity site had a higher binding capacity (Bmax = 245.6 fmol/mg protein) than the high affinity site (Bmax = 71.7 fmol/mg protein). Displacement of [3H]DHA by practolol, a selective beta 1 agent, confirmed the existence of two species of adrenoreceptors, corresponding to 21% high affinity (beta 1) and 79% low affinity (beta 2), respectively.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004082:Dihydroalprenolol / Q000378:metabolism; D006168:Guinea Pigs; D008297:Male; D011217:Practolol / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol; D011217:Practolol