ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Activities related to Na-K transport were measured in cell cultures of ground squirrel kidney cortex in order to compare these cells with those of intact kidney and of continuous cell lines. A microsomal preparation containing plasma membrane Na,K-ATPase from fresh kidney showed twice the activity of a similar preparation from 72-hour cultured cells. Na,K-ATPase of homogenates of 72-hour cells showed one-third to one-fourth the specific activity of that from 6-hour cultured cells. The associated K-dependent phosphatase activity also declined as a function of time in culture. The ouabain-sensitive influx of K into 6-hour cultured cells was twice as great as the K influx into 72-hour cells. The number of sites binding 3H-ouabain in intact cultured cells declined 81% on a cell protein basis between 6 and 72 hours in culture. This decline in ouabain binding sites was relatively greater than that of K influx, so that the K turnover number increased over this same time period.The decline in ouabain-sensitive K influx during culture was complementary to an increase in furosemide-sensitive K influx. Measurements of unidirectional and net K fluxes showed that there were three components of K influx into 3-day cultured cells: ouabain-sensitive Na:K exchange, furosemide-sensitive K:K exchange, and K diffusion. In the 6-hour cultures, however, there was no furosemide-sensitive K:K exchange.Thus, after three days in culture ground squirrel kidney cells lose a feature characteristic of the original parent cells (high Na,K-ATPase activity), and gain a feature common to many undifferentiated cultured cells (furosemidesensitive K:K exchange).
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1040990317
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