Effect of Age on the Kinetics of the Binding of Iodocyanopindolol to a Membrane Preparation of Rat Lungs

Abstract

The association (k₊₁) and dissociation (k_-1) rate constants, and the equilibrium thermodynamic binding parameters (ΔG°, ΔH° and ΔS°) of the β-adrenergic ligand [¹²⁵Iodo]cyanopindolol (ICYP) were studied in a crude lung membrane preparation of rats of different ages. There was no difference in k₊₁-values for the different age groups, while the k_-1-values were in all cases difficult to measure: almost no dissociation of ICYP from its binding site occurs. The thermodynamic properties were not affected by age. It is concluded that, in these experimental conditions, age has no effect on the kinetic parameters of the binding of ICYP to the β-adrenoceptors in rat lung.