Abstract
During compensatory renal growth 45Ca 2+ transport in basal-lateral plasma membrane vesicles isolated from the rat renal cortex have been investigated. Stimulation of Ca 2+-ATPase activity was observed, without an effect of compensatory renal growth on Na +/Ca 2+ exchanger activity and on passive Ca 2+ permeability of the vesicles. Twelve hours following unilateral nephrectomy about 40% increase of Ca 2+-ATPase activity above control value was observed and this effect was present until the end of the experimental period (7 days). When kinetic parameters for Ca 2+-ATPase were studied in native membranes, an increase V max was observed, whereas the K m for Ca 2+ was similar in control vesicles and vesicles isolated from the remnant kidney. Depletion of endogenous calmodulin resulted in a decrease of V max and an increase of K m(Ca 2+, while its addition reversed these parameters and increased the Hill coefficient from about 1 to about 2. Once again, only a significant increase of V max in vesicles isolated from the remnant kidney above the control value was observed. Finally, increase of Ca 2+-ATPase activity during compensatory renal growth could be abolished by actinomycin D, indicating that its stimulation is due to protein synthesis.
Published Version
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