JBC, Vol. 250, Issue 18, 7089-7902, Sep, 1975
Time course of termination of the glucose transport action of insulin in adipocytes
O. B. Crofford
Rapid sequence measures of changes in the rate of 14CO2 production from
[14C]glucose bathing the cells was abruptly reduced from 20 to 4
microunits/ml. Interpretation of the data in terms of glucose transport was
based on calibration experiments that described the time course of change
in 14CO2 production when [14C]glucose entry into adipocytes was slowed by
reducing the specific activity of [14C]glucose in the incubation medium.
All experiments were performed at 37 degrees in Krebs-Ringer bicarbonate
buffer at pH 7.4. Termination of the glucose transport action of insulin
(which includes insulin-receptor disassociation and all other steps leading
to decelerated glucose entry) began within 2 min and was complete within 30
min. The transition from one steady state rate of glucose transport to the
other could be approximated by an exponential process occurring with a
half-time of 14 min. For comparison, the time course of initiation of the
glucose transport action of insulin was measured under the same conditions.
The transition curve was virtually identical.