Ouabain Does Not Induce Selective Spiral Ganglion Cell Degeneration in Guinea Pigs

Figure 6

Scatter plots of aABR data and OHC loss and SGC packing densities. OHC counts and SGC packing densities are normalized and expressed as percentages of an averaged dataset from the left (untreated) cochleas. Thresholds and amplitudes are normalized and expressed as change (in dB) from pretreatment levels. (a) The variance in wave II threshold shift after ouabain treatment can be explained for 44% by OHC loss (p < 0.001). (b) The decrease in wave II amplitude is positively correlated with OHC loss. The explained variance (R²) is 45% (p < 0.001). (c) The aABR wave II threshold shift and SGC loss are moderately correlated (p < 0.001). (d) There is also a moderate positive correlation between wave II amplitude decrease and SGC packing densities (p < 0.001). Colors indicate treatment group: open symbols are left (nontreated) cochleas; right ears are shown in closed symbols colored yellow (0.01 mM ouabain), green (0.1 mM), blue (1 mM), and red (10 mM). Post hoc categorization is visualized using circles (Category 1), triangles (Category 2), and squares (Category 3).

(a) Wave II thresholds/OHC counts

(b) Wave II amplitudes/OHC counts

(c) Wave II thresholds/SGC packing density

(d) Wave II amplitudes/SGC packing density