Monitoring erythrocytes in a microchip channel that narrows uniformly: towards an improved microfluidic-based mimic of the microcirculation

The release of adenosine triphosphate (ATP) from red blood cells (RBCs) flowing through PDMS microchannels has been determined as a function of channel cross-sectional area using a design containing a channel that narrows uniformly. ATP, released from the RBCs in response to the mechanical deformation of their cell membranes, increased as the channel cross-section decreased. One sample of rabbit RBCs released 1.16 +/- 0.11, 1.92 +/- 0.14 and 2.09 +/- 0.10 microM ATP as the median cross-sectional area decreased from 4314 to 3192 to 2052 microm(2), respectively. Numerous samples (n = 6) displayed the same trend. Incubating a sample of RBCs with diamide, a substance known to stiffen cell membranes without harming the cell cytosol, provided evidence that no cell lysis occurred in the microchip device. This novel use of lab-on-a-chip technology allows for channel designs that enable an in vitro study of physiological events that occur in the microcirculation.