Table 1

Kinetic parameters for DEM metabolism in rat hepatic microsomes and isolated hepatocytes (mean ± S.D., n = 4)

In Vitro SystemPathwayVmaxS50nKmCLint
nmol/min μM μM μl/min
MicrosomesMEM3.46  ± 0.481-a 81.1  ± 5.91.28  ± 0.0925.5  ± 3.11-a 1-e
MicrosomesDOR0.42  ± 0.081-a 1-c 1.06  ± 0.261-c 423  ± 1481-a 1-c
1.48  ± 0.221-a 1-d 43.4  ± 6.91-d 35.2  ± 9.861-a 1-d
DEX microsomesMEM9.54  ± 0.971-a 114  ± 11.883.9  ± 10.21-a
DEX microsomesDOR0.28  ± 0.071-a 1-c 0.43  ± 0.181-c 693  ± 2871-a 1-c
0.60  ± 0.121-a 1-d 36.0  ± 21.81-d 21.0  ± 11.01-a 1-d
HepatocytesMEM1-a 1.86  ± 0.481-b 12.9  ± 3.92.35  ± 0.6276.4  ± 20.91-b 1-e
HepatocytesDOR1-a 0.60  ± 0.141-b 12.2  ± 2.91.36  ± 0.1228.4  ± 4.91-b 1-e
  • 1-a Values expressed per milligram protein.

  • 1-b Values expressed per 106 cells.

  • 1-c Parameters for the high-affinity, low-capacity site.

  • 1-d Parameters for the low-affinity, high-capacity site.

  • 1-e CLmax.