An advanced recording and analysis system for the differentiation of guinea pig cough responses to citric acid and prostaglandin E2 in real time
Fig 6
Acoustic analysis of coughs evoked by aerosolized CA and PGE2.
Typical sound waveforms (top) and spectrograms (bottom) of the coughs evoked by CA and PGE2 are illustrated in A and B, respectively. A: At the top, the dashed lines separate the initial phases from the following phase in response to CA. The arrowheads in the middle panel of the spectrogram point to a series of horizontal bands, while the arrows in the right panel indicate the vertical lines. Note: The scale of the Y-axis at the top of B is different from that of A. B: Group data of sound power spectral densities (PSDs) in which the spots are the individual values of the PSDs (229 and 244 coughs in the CA and PGE2 groups respectively), and the lines with markers represent the averaged values and standard errors. The baseline values of power density (5 data points from each animal) were generated from the sound recordings before the first 5 coughs provoked by CA or PGE2 exposure. Compared to the baseline noise at a given audio frequency, PSDs in response to CA (0.5 to 3.5 kHz, P < 0.01) and PGE2 (0.5 to 2.75 kHz, P < 0.01; and 2.8 to 3.3 kHz, P < 0.05) are significantly higher. Both CA- and PGE2-evoked coughs have peak PSDs located over a range of 0.6 to 2.2 kHz, with the topmost value at approximately 1.0 kHz, but the PSDs at the corresponding frequencies in the PGE2-evoked coughs are much lower than those in CA-evoked coughs. C and D: Comparisons of the peak sound intensity and the integrated intensity between CA and PGE2 groups, respectively. The scattered dots are individual data and the dots with standard error bars are the mean values. The shaded areas indicate the distributions of individual data. All group data from 7 guinea pigs from the CA and PGE2 groups are presented as the mean ± SE. ** P < 0.01, PGE2 vs. CA.