Previous studies on the release of endogenous pyrogen from rabbit exudate granulocytes in vitro (1) have revealed: (a) that large amounts of pyrogen are released when the cells are incubated (37°C) in 0.15 M NaC1; (b) that the release is blocked if physiological concentrations of K + are added to the medium; and (c) that inhibition by ouabain of K + transport into the cells nullifies the blocking effect of K + on the release process. These results indicate that deprivation of K ions causes exudate granulocytes to release endogenous pyrogen. Other cellular proteins (e.g., aldolase) are also released with the pyrogen (1). Furthermore, it has been found that sulfhydryl reagents, such as iodoacetate, p-chloromercuribenzoate, and N-ethylmaleimide, which inhibit the energyrequiring N a -K transport system of the cells (2), also inhibit the release process (3). The present studies were undertaken to investigate further the mechanism whereby K + deprivation stimulates exudate granulocytes to release pyrogen.
Material and MethodsThe methods used to exclude extraneous pyrogens, to obtain exudate granulocytes from rabbits, and to assay granulocytic pyrogen, have been described elsewhere (4, 5).Plasma was separated from rabbit blood after the addition of heparin (10 IU per ml of Liquaemin, Organon, Inc., West Orange, N. J.). Endotoxin from Escherlchla coli 0111:B4 was purchased from Difco Laboratories, Detroit, Mich.; inulin from Mann Research Laboratories, Inc., New York, N.Y.; and puromycin dihydrochloride from Nutritional Biochemicals Corp,, Cleveland, Ohio; modified Hanks' solution (MH) was prepared as described in reference (6).