INFLUENCE OF RESERPINE AND ETHYLENEDIAMINETETRAACETIC ACID (EDTA) ON SEROTONIN STORAGE ORGANELLES OF BLOOD-PLATELETS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 87  (3) , 633-646
Abstract
The influence of reserpine on the serotonin-rich organelles (dense bodies) in platelets from dogs, rabbits and humans was evaluated. Reserpine markedly depressed the levels of stored serotonin in human and animal platelets, accompanied by a small decrease in platelet ATP but no change in platelet ADP content. Thin sections of human platelets showed no change in the number or morphology of serotonin storage organelles during reserpine therapy, whereas a profound decrease in the size and number of dense bodies occurred in platelets from rabbits treated with reserpine. Dog platelets also showed a decrease in the number and density of serotonin storage organelles after reserpine therapy. The basis for the difference between rabbit and human platelets was explored by fixing platelets in glutaraldehyde and Os in the presence or absence of the chelating agent ethylenediaminetetraacetic acid (EDTA). Most of the dense bodies in fixed human platelets were removed by EDTA while rabbit platelet dense bodies remained essentially intact. The opacity of rabbit platelet dense bodies following fixation with glutaraldehyde and Os appear to relate primarily to their serotonin content, while the electron density of human serotonin storage organelles in fixed cells is due primarily to their Ca content. Further confirmation of this concept came from studies of platelets using the whole mount technique. Rabbit platelet serotonin storage organelles were found to lack the inherent opacity of the human dense bodies, a finding consistent with the lower concentration of Ca in the rabbit organelles.