Protamine-induced permeability changes in the neutrophil plasma membrane as the basis of activation of exocytosis.
Protamine induces a gradual change in plasma membrane permeability in rabbit neutrophils, which is evident from the increase of indol fluorescence, and the leakage of quin2 from quin2-loaded neutrophils. The influx of extracellular Ca2+ into the neutrophil provides an explanation for exocytosis which occurs in the presence of Ca2+ and protamine. The dependence of exocytosis on Ca2+ concentration follows the same pattern as is observed in neutrophils permeabilized by other means. In the absence of Ca2+, and in the presence of protamine, La3+ has an activating effect on exocytosis. At higher concentrations La3+ inhibits exocytosis that occurs in the presence of Ca2+ and protamine, as do some other metal ions. The resemblance between the membrane effects of a number of toxins, as reported in literature, and protamine-induced membrane damage suggests that they occur via the same mechanism.
Elferink
J G
JG
Department of Medical Biochemistry, University of Leiden, The Netherlands.
D000634:Aminoquinolines / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D002614:Chelating Agents / Q000378:metabolism; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D005456:Fluorescent Dyes / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007811:Lanthanum / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D011479:Protamines / Q000187:drug effects*; D011817:Rabbits; D013997:Time Factors
D000634:Aminoquinolines; D002614:Chelating Agents; D005456:Fluorescent Dyes; D011479:Protamines; D007811:Lanthanum; C035739:Quin2; D002118:Calcium