Study of physical mechanisms of insulin reception

The bilayer lipid membrane (BLM) was used to reconstitute the hormonal reception system for insulin. The effect of insulin on both unmodified BLM and BLM modified by rat liver plasma membrane fragments was studied by measuring the viscoelastic parameters of membranes--the modulus of elasticity in the direction perpendicular to the membrane plane, E perpendicular to, and the coefficient of dynamic viscosity, eta. The effect of insulin (in concentration of 10(-10) mol la1) on modified membranes resulted in a much greater (about 30-40%) decrease of E perpendicular compared to that on unmodified BLM. Analysis of the developed model of the membrane showed that in the vicinity of insulin--in the case of the unmodified BLM--and in the vicinity of hormone receptors--in the case of modified BLM--there appeared extensive regions of a changed membrane structure which could cause cooperative changes in the studied viscoelastic parameters of BLM. These changes were considerably influenced by the initial value of the BLM modulus of elasticity, fragment concentration and by the content of membrane cholesterol, which has a strong inhibitory effect. The effect of the insulin antagonist glucagon on modified BLM resulted in opposite changes of the relative value of E perpendicular compared to the effect of insulin.