Regional Differences in the Binding Affinities of β-Adrenergic Receptors in the Canine Kidney Cortex 1

Summary

β-Adrenergic receptors were characterized from plasma membranes obtained from two different regions of the canine kidney cortex by studying their binding of the radiolabeled β-adrenergic antagonist [³H]dihydroalprenolol. Total receptor occupancy was slightly but not significantly greater in outer cortical membranes; the dissociation constant was approximately twofold higher in the outer cortical membranes. A greater binding capacity demonstrated for inner cortical membranes was due to greater affinity of the receptors in this area rather than a difference in receptor sites. β-Adrenergic stereospecificity was demonstrated in both membranes; 1-propranolol was more effective in displacing [³H]DHA than d-propranolol.