Calcium and oestrogen interactions upon the rat thymic lymphocyte plasma membrane.

Summary When isolated thymic lymphocytes are equilibrated with a carbocyanine dye the degree of fluorescence is indicative of the potential difference across the plasma membrane. Increments in extracellular calcium concentrations trigger a decrease in fluorescence intensity which represents a membrane hyperpolarisation. This hyperpolarisation cannot be reversed by subsequent chelation of the calcium. Oestradiol and natural oestrogens reduced this calcium-induced potential alterations. These same steroids also blocked the calcium-induced mitotic stimulation apparent in this same cell type.

[1]  R. Farías,et al.  Hormone action and membrane fluidity: effect of insulin and cortisol on the Hill coefficients of rat erythrocyte membrane-bound acetylcholinesterase and (Na+ + K+)-ATPase. , 1975, Biochemical and biophysical research communications.

[2]  N. Cittanova,et al.  Surface behaviour of oestradiol-17β , 1975 .

[3]  J. Gorski,et al.  Stereospecific binding of estrogens in the rat uterus. , 1965, Archives of biochemistry and biophysics.

[4]  J. Morgan,et al.  Requirements for divalent cations by hormonal mitogens and their interactions with sex steroids. , 1975, Biochemical and biophysical research communications.

[5]  S. Ohnishi,et al.  Clustering of lecithin molecules in phosphatidylserine membranes induced by calcium ion binding to phosphatidylserine. , 1973, Biochemical and biophysical research communications.

[6]  R. King,et al.  THE LOCALIZATION OF [6,7-3H]OESTRADIOL-17β IN RAT UTERUS , 1966 .

[7]  A. D. Perris,et al.  The influence of sex steroids on calcium‐ and magnesium‐induced mitogenesis in isolated rat thymic lymphocytes , 1974, Journal of cellular physiology.

[8]  P. Romero,et al.  The control by internal calcium of membrane permeability to sodium and potassium , 1971, The Journal of physiology.

[9]  G R Smith,et al.  Inhibitory action of oestrogen on calcium-induced mitosis in rat bone marrow and thymus. , 1975, The Journal of endocrinology.

[10]  H. Lardy,et al.  A23187: a divalent cation ionophore. , 1972, The Journal of biological chemistry.

[11]  C H Wang,et al.  Studies on the mechanism by which cyanine dyes measure membrane potential in red blood cells and phosphatidylcholine vesicles. , 1974, Biochemistry.

[12]  D. Tosteson,et al.  The Effect of Valinomycin on the Ionic Permeability of Thin Lipid Membranes , 1967, The Journal of general physiology.

[13]  S. Cohen.  The conjugated steroids; I. A fractionation procedure for the rapid isolation of estriol monoglucuronide from human pregnancy urine. , 1950, The Journal of biological chemistry.

[14]  J. Whitfield,et al.  REDUCTION OF MITOTIC DELAY IN IRRADIATED SUSPENSION CULTURES OF RAT THYMOCYTES BY AN ELEVATED SALT CONCENTRATION. , 1964, Experimental cell research.