TABLE 2

Activation properties of 1,4-dihydropyridines measured in FRT cells expressing G551D-CFTR Values for Vmax and Ka were obtained from experiments of the type shown in Fig. 4B and are the mean ± S.E.M. of 5 to 10 experiments. The activity elicited by forskolin 20 μM alone was negligible and therefore not subtracted. The compounds are listed in order of decreasing potency. Genistein properties are reported for comparison.

VmaxKa
mM / s μM
Racemates
   Felodipine 0.145 ± 0.013 23.3 ± 2.1
   Nicardipine 0.105 ± 0.006 25.9 ± 2.1
   Nitrendipine 0.130 ± 0.004 26.3 ± 1.0
   Nifedipine 0.058 ± 0.005 34.2 ± 1.9*
   Nimodipine 0.078 ± 0.004 36.2 ± 2.3
   Isradipine 0.100 ± 0.006 37.5 ± 2.3
   Amlodipine Inactive
   Lercanidipine Inactive
Enantiomers
   (+)-Isradipine 0.085 ± 0.006 25.8 ± 2.2
   (–)-BayK-8644 0.081 ± 0.002 30.6 ± 1.4
   (+)-BayK-8644 0.116 ± 0.005 36.5 ± 3.1
   (+)-Niguldipine 0.034 ± 0.002 87 ± 4
   (–)-Isradipine 0.049 ± 0.003 88 ± 5†
   (–)-Niguldipine Inactive
   Genistein 0.097 ± 0.007 90 ± 10

  • ↵* Ka value was significantly (p < 0.05) higher than that of the preceding compound

  • ↵† Ka value was significantly higher than that of the other isomer