The effect of estrogen and progesterone on β-adrenergic receptor activity in rabbit lung tissue☆☆☆

Abstract Study of the effect of sex steroids on the development of β-adrenergic receptors may be essential to an understanding of the mechanisms of both lung maturation and the initiation of labor, ( 3 H)Dihydroalprenolol (DHA) was used to quantify β-adrenergic receptor sites in mature and immature rabbit lung tissue. DHA binding was rapid, saturable, of high affinity (dissociation constant=2 nM), and of low capacity (246 to 576 fmoles/mg of protein), and adrenergic competitors demonstrated both stereoselectivity ([−]isomer ⪢ [+]isomer) and a rank order of potency (isoproterenol ⪢ norepinephrine > epinephrine) characteristic of the β-adrenergic receptor. β-Adrenergic receptors in the lung tissue of both mature and immature female New Zealand White rabbits were investigated under various sex steroid situations. Estrogen (diethylstilbestrol, 5 μg/day for 10 days) increased the β-adrenergic receptor site number in immature rabbits compared to matched controls (435 versus 339 fmoles/mg of protein, p