Relationship between the fluidity of the membrane lipids and the activity of the membrane-bound proteins: The effects of lidocaine on the adenylate cyclase activity of rat myocardium

1. 1. The lidocaine effects on the basal adenylate cyclase activity of the studied membranes depend on the substrate concentration: the drug has an inhibiting effect on non-saturating ATP concentrations, but displays a stimulating effect on the saturating ones. 2. 2. In the presence of maximally stimulating NaF concentrations, lidocaine further stimulates the adenylate cyclase activity through all the ATP concentrations used. 3. 3. In the presence of ATP saturating concentrations, the adenylate cyclase activity stimulated by various Gpp(NH)p concentrations, is inhibited in the presence of lidocaine as well as the enzymic activity stimulated by several 1-isoproterenol concentrations in the presence of a fixed Gpp(NH)p concentration.