Investigating mechanosensitive channels activation in concert with the mechanical properties of red blood cells

The activity of the mechanosensitive Ca2+ permeable channels expressed in the membrane of the red blood cells (RBC) is determined both by the mechanical stimuli and the mechanical properties of the cell. Therefore, it is of most importance to correlate the triggering stimulus with the mechanical properties. In this paper, we propose an approach to determine the activation pressure of the mechanosensitive channels and concomitantly evaluate cell mechanical properties as Young’s Modulus, membrane tension and viscosity, for individual cells. Cell deformation was accomplished by micro- pipette aspiration with a controlled pressure ramp and recorded by brightfield imaging to determine the mechanical properties. The Ca2+ transient was concomitantly monitored by fluorescence imaging, to get the activation pressure. The technique was validated comparing the behavior of three pools of RBCs, probed at different intervals of time after the cell suspension preparation by the same mechanical stimuli. We found relevant changes of the activation pressure, associated with the alteration of the mechanical properties, the latest becoming significant with the passage of time. Our approach opens a new direction to investigate the correlation between mechanosensitivity and mechanical properties for individual RBCs, which can be extended to other cells, in suspension or plated, under controlled environmental conditions.