INFLUENCE OF AGING ON FLUIDITY AND COUPLING BETWEEN BETA-RECEPTORS AND G-PROTEINS IN RAT LUNG MEMBRANES

We tested the hypothesis that in rat lung membranes, the age-related d ecline in the percentage of beta-receptors coupled with high affinity to G-proteins, is due to limitation of the diffusion caused by a decre ase in membrane fluidity. We measured both parameters simultaneously i n a crude membrane preparation from lungs of rat of different age. In contrast to what is found in crude membrane preparations from rat live r and brain, in rat lung fluidity was increased upon aging. We conclud e that the age-related alteration in coupling between receptor and G-p rotein is difficult to explain by alterations of membrane fluidity.