Figure 1

Schematic display that connects requirements for the fast sodium channel function (field A1) with various aspects of cell physiology (left fields A2 to A9), neuron reactivity (middle top fields B1 to B3), gas traffic in blood (right top fields C1 to C3) or circulation (bottom right fields D1 to D4). The pivotal role is reserved for the ECF protein concentrations (central white fields A6, B1, C1, D1) as causes of a local Donnan effect and colloid osmotic pressure. Low IF proteins allow stable resting potentials more negative than -80 mV to be generated. Plasma proteins are optimized to help the chloride shift in RBCs, which is important for gas transport and in pulmonary circulation, peripheral tissue fluid traffic and renal control of arterial pressure.