Membrane marker movement on sympathetic axons in tissue culture

Retrograde (somatopetal) movement of two tightly bound membrane markers along culture chick sympathetic neurites has been observed. Concanavalin A coated red blood cells (ConA-RBCs) bound to these sympathetic neurites and exhibited retrograde movement if the point of attachment was close to the cell soma. All ConA-RBCs bound within 10 mu-m of the cell body moved within the three hour observation period but some of those farther than 60 mu-m moved toward the soma during this period. ConA-RBCs moved at rates ranging from 11-84 mu-m/hr with a mean and standard error of 49±6 mu-m/hr (n=18). The rate of this retrograde ConA-RBCs movement increased with distance from the cell soma according to the equation: R=11 (±2) + 1.28 (±0.07) D, where R represents the rate in mu-m/hr and D represents the distance from the soma in mu-m. The binding of ConA-RBCs to sympathetic neurites showed specificity for concanavalin A (ConA) receptors in the membrane since either pretreatment of the neurons with ConA or the presence of 25mM alpha-methyl-glucopyranoside prevented the binding. Thus, the retro-grade movement of ConA-RBCs appears to demonstrate the somatopetal movement of ConA receptors within the axon membrane. Untreated polystyrene beads (1.1 mu-m) also showed retrograde movement after binding non-specifically to the neurite membrane. These beads moved at rates similar to those of the ConA-RBCs. However, unlike ConA-RBC movement the smaller polystyrene beads were observed to move at all distance form the soma. The retrograde movement of these untreated beads suggests that ConA-RBC movement is not due the presence of the ConA. However, some dose-related pharmacological effects of ConA on cultured sympathetic neurons were observed. ConA (100 mu-g/ml) completely prevented axon sprouting of dislocated neurons but had no apparent effect on adhesion of these cells to the substrate. IN established whole ganglion cultures the same dose of ConA caused both bundling of nerve fibers due to fiber reaction around the perimeter of the nerve fiber halo and flattening of the unretracted growth cones.