Lack of exchange among plasma proteins in narrow spaces on glass, demonstrated with metal oxide coatings.

Onto 'activating' surfaces, intact normal plasma deposits an overlapping sequence of proteins, each being desorbed by the next. Ultimately, high molecular weight kininogen (HMK) is deposited unless contact was too short, or space between 2 surfaces too narrow. Thus, injected between a glass slide and a convex lens, intact plasma will leave a disk of HMK with a center of fibrinogen. We describe here how the exchange of proteins on the surface can be demonstrated by staining the adsorbate with a metal oxide suspension. Subsequent flooding of the preparation with more normal plasma causes lift-off of the oxide where underlying fibrinogen is being displaced by the HMK of the newly applied plasma. Kininogen-deficient plasma fails to remove any oxide, while normal plasma can remove nearly all of the oxide and adsorbate, left on glass by HMK-deficient plasma.