LIPID-GLASS ADHESION IN GIGA-SEALED PATCH-CLAMPED MEMBRANES

Adhesion between patch-clamped lipid membranes and glass micropipettes is measured by high contrast video imaging of the mechanical response to the application of suction pressure across the patch. The free pat ch of membrane reversibly alters both its contact angle and radius of curvature on pressure changes. The assumption that an adhesive force b etween the membrane and the pipette can sustain normal tension up to a maximum T-a at the edge of the free patch accounts for the observed m echanical responses. When the normal component of the pressure-induced membrane tension exceeds T-a membrane at the contact point between th e free patch and the lipid-glass interface is pulled away from the pip ette wall, resulting in a decreased radius of curvature for the patch and an increased contact angle. Measurements of the membrane radius of curvature as a function of the suction pressure and pipette radius de termine line adhesion tensions T-2 which range from 0.5 to 4.0 dyn/cm. Similar behavior of patch-clamped cell membranes implies similar adhe sion mechanics.