Resting potential of cell membrane

It is possible that the stationary-state situations leading to an active ion transport occur only in localized regions of the membrane, i.e., at ATPase molecule units with diameters of about 50 A and a length of 80 A. The vectorial ion currents at locations with a mixed potential and special equipotential lines would appear phenomenologically like ionic channels. If the membrane area where the passive diffusion occurs is large, it may determine the rest potential of the whole cell. 

Fromm and Spanswick [79] studied inhibiting effects of DNP on the excitability of willow by recording the resting potential of the phloem cells. In willow, 10 " M DNP rapidly depolarized the membrane potential by about 50 mV. 

The ventricular action potential is depicted in Fig. 6-2.2 Myocyte resting membrane potential is usually -70 to -90 mV, due to the action of the sodium-potassium adenosine triphosphatase (ATPase) pump, which maintains relatively high extracellular sodium concentrations and relatively low extracellular potassium concentrations. During each action potential cycle, the potential of the membrane increases to a threshold potential, usually -60 to -80 mV. When the membrane potential reaches this threshold, the fast sodium channels open, allowing sodium ions to rapidly enter the cell. This rapid influx of positive ions... 

Investigations of the cellular effects of radiofrequency radiation provide evidence of damage to various types of avian and mammalian cells. These effects involve radiofrequency interactions with cell membranes, especially the plasma membrane. Effects include alterations in membrane cation transport, Na+/K+-ATPase activity, protein kinase activity, neutrophil precursor membrane receptors, firing rates and resting potentials of neurons, brain cell metabolism, DNA and RNA synthesis in glioma cells, and mitogenic effects on human lymphocytes (Cleary 1990). 

Our studies show that DHAVM has no effect on the resting input conductance or resting potential of the bag membrane of A. suum muscle cells. This is in contrast with the effects of AVMs on other invertebrate muscle preparations. In the opener and stretcher muscles of lobster, AVM Bla causes an increase in the conductance of the muscle membrane to chloride ions which is thought to result from the activation of GABA receptor/chloride ion channels (31). Similarly, the chloride conductance of locust extensor tibiae muscle fibers is increased by exposure to DHAVM (30). 

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