The Role of Ion Channels in Cellular Mechanotransduction of Hydrostatic Pressure

While pressure is a common mechanical parameter in the physiology of many organ systems, such as the vasculature, lungs, eyes, bladder, bone marrow, and brain, the conventional view that cells can only detect the deformation of physical structures has deterred further investigation of the effect of pressure itself. This is due to the long-lasting assumption that cells are incompressible so that they do not deform under hydrostatic pressure and cannot detect this physical quantity. The results of well-controlled studies, however, warrant careful reevaluation of this concept. Studies reviewed herein suggest that multiple mammalian cell types are sensitive to pure hydrostatic pressure within normal physiological ranges, and the signals may be mediated by activities of membrane-bound ion channels and transporters. Pressure changes as small as 0.5 cm H2O (50 Pa) have been shown to modulate potassium currents in vestibular type II hair cells from guinea pig utricles (Duwel et al. 2003), despite the fact that this is equivalent to less than a 4 m change in altitude near sea level. How such a small change in pressure can affect certain cell types while apparently having little effect on others remains an open question. Investigations of these phenomena are continuing to improve our understanding of pressure mechanotransduction and are critical to potentially treating pathophysiological pressure-related conditions in multiple organ systems.