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K.W. Ruether, M. Leitges, M. Pennesi, S.M. Wu, O. Strauss; Delayed ERG b-wave Switching off in PKC-alpha Knock Out Mice . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4882.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: In the rodent retina Ca2+-dependent protein kinase C alpha (PKCalpha) has been shown to be localized in rod bipolar, amacrine and ganglion cells. The present study was performed to elucidate the functional role of PKCalpha in the mouse retina. Methods: 10 PKCalpha knock out mice and 9 controls have been examined by Ganzfeld electroretinograms (ERGs). Scotopic and photopic ERGs were performed in the anaesthetized mice. A-, b, and c-waves were analyzed. Light responses from bipolar cells, amacrine cells and ganglion cells were recorded from dark-adapted retinal slices of the PKC knock out and control mice with the whole-cell voltage clamp technique. Results: Scotopic a-, b- and c-wave amplitudes showed no significant differences between knock outs and controls. The same applied for cone amplitudes and implicit times. However, the rod b-wave implicit times were significantly different leading to a substantially change of the curve shape. In controls, the b-wave recording reached baseline at 400 ms at the latest (3 cds/m2), the b-wave of the knock outs needed more than 500 ms. At 240 ms, the difference between the a-wave trough and the b-wave curve was 666 µV (SEM 51.1 µV) in knock outs compared to 294 µV (SEM 53.4 µV) in the controls (p = 0.0001, t-test). In addition, this delayed switching off lead to a fusion between b- and c-waves to one complex. Changes in light responses of individual bipolar cells, amacrine cells and ganglion cells are under investigation. Conclusions: Pigment epithelium and photoreceptor function seemed to be unaffected in PKCalpha knock out mice. The changed shape of the scotopic b-wave may reflect a change of rod bipolar cell function. One explanation could be that PKC alpha modulates the voltage-dependent K+ currents that speed up the switching-off process of photocurrents in rod bipolar cells. Potential changes of amacrine cell and ganglion cell function cannot be excluded by our results obtained so far.
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