The transmitter-induced change in slope conductance of a receptor membrane as a function of the resting potential and equilibrium potential of the ion involved.
Change in slope conductance has been widely used to evaluate the ion-channel activation by receptor agonists of various postsynaptic membranes. However, the agonist-induced change in slope conductance (delta G) depends not only on the change in membrane ionic permeabilities (delta P) but also on the changes in resting potential (E) and equilibrium potential (EA) of the ion involved (A). A constant field theory was applied to describe delta GA as a function of delta PA, E and EA, assuming that delta PA is not affected by the change in E or EA. This equation predicts that delta GNa will decrease if the membrane is depolarized or when ENa becomes more positive. Similarly, delta GK is expected to increase if the membrane is depolarized or when EK becomes more negative. Further, the equation describes that delta GCl will increase if the membrane is depolarized or when ECl becomes less negative. These changes in GNa, GK and GCl are well consistent with many data previously obtained from various types of receptor membranes. We conclude that the values of slope conductance measured at different E or EA must be carefully corrected in order to estimate the real voltage dependence of delta P or the ion-channel activation by receptor agonists.
D000818:Animals; D002463:Cell Membrane Permeability; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D017981:Receptors, Neurotransmitter / Q000502:physiology*
D007473:Ion Channels; D017981:Receptors, Neurotransmitter