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Biomedical subjects

R D Moore

Publications and source records attributed to R D Moore.

At least 199 records · Page 11Linked to original sources
PubMed1976

A possible mechanism for concentrating sodium and potassium in the cell nucleus.

A dynamic, nonequilibrium mechanism is proposed for concentrating both Na+ and K+ in the cell nucleus. The model is consistent with experiment observations and with known properties of cell membranes. This model could explaing the high nucleoplasm to cytoplasm ratios of Na+ and/or K+ reported for liver kidney, thymus, frog skin, ascites cells, and amphibian oocytes.

Animals↗
PubMed1975

Effect of insulin upon membrane-bound (Na+ + K+)-ATPase extracted from frog skeletal muscle.

1. Insulin stimulates the activity of membrane-bound ATPase isolated from frog skeletal muscle and from rat brain. The increase in activity of the membrane-bound ATPase system isolated from frog ranged from 9-8 to 53% at concentrations of Na+ (25 mM), K+ (10 mM), and ATP (2 mM) similar to those in in vivo experiments conducted previously (Moore, 1973). The increased activity of the membrane-bound ATPase is, therefore, at least as great as the insulin-induced increase in Na efflux (10-38%) from intact cells (Moore, 1973). If the concentration of Na+ is lowered to 4 mM and that of ATP lowered to 0-5 mM albumin, and 10(6) M, the increase in ouabain-inhibitable ATPase activity can reach as high as 400%. 2. Ouabain, at a concentration (10(-3) M) sufficient to inhibit stimulation of the frog ATPase by increasing Na from 4 to 25 mM, completely blocked the stimulation of ATPase activity due to insulin. 3. At 2 mM-ATP, 100 mM-Na+, and 20 mM-K+, conditions which maximally activate the (Na+ + K+)-ATPase, insulin did not increase the ATPase, activity. Stimulation was consistently seen at 10 mM-K+, 0-5 mM-ATP, and either 4 mM or 25 mM-Na+. 4. The finding that insulin does not stimulate the ATPase activity in conditions in which the (Na+ + K+)-ATPase component is maximally activated and especially the fact that ouabain can reproducibly inhibit insulin stimulation of the membrane-bound ATPase activity strongly suggest that interaction of insulin with its receptor upon the plasma membrane somehow stimulates the (Na+ + K+)-ATPase system (ouabain sensitive; ATP phosphohydrolase, EC (3.6.1.3). These results are consistent with previous studies of the effect of insulin upon Na efflux from intact cells (Moore, 1973) and support the previous conclusion that the component of Na efflux stimulated by insulin is active. The evidence suggests that insulin probably does not affect Vmax of the (Na+ + K+)-ATPase system, but may increase the affinity of the enzyme system to one or more effectors, most likely Na+, ATP, and perhaps K+. 5. Oxidized glutathione (2-7 X 10(-6) M), 10(-6) M, 10(-7) M, and 10(-8) M cyclic AMP did not affect the ATPase activity 10(-6)Malbumin, and . 6. The results are consistent with the view that the Na pump, (Na+ + K+)-ATPase, is intimately involved with the physiological action of insulin and may be transducer between the binding of insulin to its receptor on the plasma membrane and the cellular actions of insulin.

Adenosine Triphosphatases↗
PubMed1975

Transplantation of autoimmune potential. II. Glomerulonephritis in lethally irradiated DBA/2 recipients of NZB bone marrow cells.

Lethally irradiated (850 rads) DBA/2 mice which had been transplanted 10 months previously with 2 times 10-6 bone marrow cells from 3-week-old donors of the H-2-histocompatible NZB, BALB/c and DBA/2 strains were examined for manifestations of autoimmune disease. Also studied were lethally irradiated (950 rads) NZB mice grafted with NZB marrow. Strongly positive antinuclear antibody responses were present in all NZB and DBA/2 recipients of NZB marrow, but absent in DBA/2 mice grafted with BALB/c and DBA/2 marrow cells. The antinuclear antibody-positive animals had glomerulonephritis with the deposition of globulin in or along the basement membranes. These observations support the view that the potential for autoantibody formation and subsequent autoimmune disease development is inherent to the NZB hemopoietic stem cell and their progeny.

Animals↗
PubMed1973

Effect of insulin upon the sodium pump in frog skeletal muscle.

1. Insulin increased the rate of net Na extrusion from Na-loaded frog skeletal muscle into glucose-free Na-Ringer. After a 90 min period of efflux, the insulin-treated muscles contained approximately 11% less intracellular water than did their controls. This decrease in intracellular water resulted in an increase in the concentration of intracellular K, [K(+)](i), even though there was no definite effect upon net K flux. In spite of the decrease in intracellular water, [Na(+)](i) was lower in those muscles treated with 500 m-u. insulin/ml. than in the controls.2. Insulin consistently increased (22)Na efflux into Na-Ringer containing either 10 or 2.5 mM-K(+). This effect was reversible and was not produced by other proteins.3. Acetylstrophanthidin (5 x 10(-6)M) blocked all or nearly all net Na efflux even in the presence of insulin. The presence of this concentration of acetylstrophanthidin or of K-free Na-Ringer inhibited the effect of insulin upon (22)Na efflux from Na-loaded muscles.4. All of the above results indicate that insulin in some way increases the activity of the Na pump. The inhibition by K-free Na-Ringer also suggests that this is not due to production of additional pump sites.5. Insulin also increased (22)Na efflux and net sodium efflux into Li-Ringer. When the new steady-state was reached after addition of insulin, the (22)Na kinetics still obeyed a power relation to intracellular (22)Na. However, in every single case, insulin resulted in a decrease of approximately 18% in the exponent, n.6. Curve-fitting of the kinetic data to equations based upon a three-site model of the Na pump suggests that insulin increases the affinity of the sites toward Na(+). In terms of Eisenman's theory of ion selectivity, this would indicate an increase in the anionic field strength of the Na-carrying sites and also predict that the increase in affinity for H(+) would be greater than that for Na(+). This latter prediction is entirely consistent with the observed decrease in n.7. The results suggest that insulin may be increasing H(+) efflux as well as Na(+) efflux and thereby may be increasing intracellular pH. It is suggested that some of the intracellular effects of insulin might be mediated by such an effect.

Animals↗