NANOPHYSIOLOGY OF CELLS, CHANNELS AND NUCLEAR PORES - Life at the Nanoscale: Atomic Force Microscopy of Live Cells - page 132

time, cells soften ( Fig. 6.12 ). Elevated extracellular (“systemic”) potassium
concentrations (>5.5 mM) usually measured in the blood plasma frequently
occur as a severe symptom associated with kidney disease. However,
“local” potassium concentrations up to 15 mM are absolutely normal in
the interstitium of muscle during physical exercise 27 and during increased
neuronal activity in brain. 28 As a functional consequence of swelling and
softening, vascular endothelial cells undergo more pronounced shear-stress-
mediated (reversible) deformations which result in enhanced NO formation.

6.2.5 The “Solaon-Gelaon” Hypothesis

Endothelial cells are subjected to large changes in cell shape (e.g. during
dilation/constriction of blood vessels, particularly with each contraction of
the heart) and can adjust best to such alterations if the deformability (physical
compliance) of the cells is high.

Figure 6.13. Concept of how sodium and potassium control the dynamic cortical zone
(cell shell).

At least two linear slopes have been described in the indentation curves,
the irst tends to be lat while the second is steeper (see Fig. 6.9 ) . The irst lat
slope indicates a low stiffness and is limited to the submembranous cortex
of the cell (cell shell). Obviously, there is a luidic layer beneath the plasma
membrane, which is highly dynamic in terms of thickness and viscosity. A