Iodohydroxybenzylpindolol Binding to β-Adrenergic Receptors of Diabetic and Control Rat Adipocytes' Crude Membrane

Summary

We have characterized the binding of [¹²⁵I]-Iodohydroxybenzylpindolol to rat adipocytes' crude membrane. The binding was rapid, reaching equilibrium within 19 min. Binding of [¹²⁵I]-Iodohydroxybenzylpindolol wasm saturable with 9 nM. Half-maximal saturation provided an estimated Kd of 2.42 nM. The order for ¹²⁵IHYP displacement by various compounds was (-)-propranolol (-)-isoproterenol > (-)-epinephrine > (-)-norepinephrine. [¹²⁵I]-Iodohydroxybenzylpindolol binding was more sensitive to L-propranolol inhibition in crude membrane prepared from diabetic rat fat cells than in those prepared from controls.

The basal cAMP level was identical in diabetic and control rat crude membrane. Isoproterenol increased the cAMP level in diabetic more than in control rats.

Key-Words:

β-Adrenergic Receptors - Control and Diabetic Adipocyte's Crude Membrane - [¹²⁵I]-Iodohydroxybenzylpindolol