Table 1.

Effects of blocking NMDA receptors, of inhibitors of sGC, PKG, cGMP-degrading phosphodiesterase, and nitric oxide synthase, and of low-frequency stimulation of cGMP dynamics after tetanus

TreatmentcGMP (% of basal before tetanus)
Time after tetanus
10 sec5 min60 min
None132  ± 4*88  ± 3*78  ± 3*
(n = 20)(n = 28)(n = 8)
50 μm APV98  ± 3103  ± 895  ± 3
(n = 8) (n = 7) (n = 8)
10 μm ODQ103  ± 3102  ± 8105  ± 5
(n = 5) (n = 6) (n = 7)
10 μmRp-8-Br-cGMPS117  ± 5*137  ± 10*96  ± 9
(n = 5) (n = 7) (n = 5)
2 μm zaprinast139  ± 13*121  ± 6*105  ± 6
(n = 5) (n = 6) (n = 8)
100 μmnitroarginine96  ± 799  ± 1093  ± 6
(n = 7) (n = 5) (n = 4)
Low-frequency stimulation94  ± 396  ± 396  ± 3
(n = 6) (n = 6) (n = 7)
Control without any stimulation98  ± 498  ± 5104  ± 4
(n = 8) (n = 8) (n = 8)
  • Experiments were performed as in Figure 2. LTP in rat hippocampal slices was induced as described in Materials and Methods. Slices were incubated with the indicated concentrations of the inhibitors for 30 min before application of the tetanus and taken at 0 and 10 sec and 5 and 60 min after tetanus. Values are expressed as percentage of cGMP content in nonstimulated slices and are the mean ± SEM of the indicated number of samples per point. Values significantly different from cGMP in nonstimulated slices are indicated;

  • * p < 0.05.