Figure 7. Properties of high threshold serosal rectal afferents in C57BL/6 and ls/ls mice.

A, the stretch sensitivity of high threshold rectal afferents did not differ between control and ls/ls mice (note the low rate of firing by comparison with Fig. 6E and G), although the sensitivity of serosal afferents to von Frey hair probing was significantly reduced in ls/ls mice at high intensity stimuli (B). C, numbers of serosal afferents in each rectal nerve did not differ significantly between ls/ls and control mice. D, comparison of thresholds to circumferential distension between 3 classes of afferents in both wild-type and ls/ls mice show that serosal afferents had significantly higher thresholds than either muscular or muscular-mucosal afferents. E and F, the relative proportions of each class of afferents recorded from rectal nerves in control and ls/ls mice differed, reflecting the reduced numbers of low threshold wide-dynamic range fibres. G shows relative contribution of low threshold (LT) and high threshold (HT) afferents on the y-axis in the total mean firing frequency (in Hz) in response to stretch. High threshold afferents contribute little to the total rectal nerve firing even at maximum stretch. H and I show that responses to stretch of low threshold capsaicin-sensitive and capsaicin-resistant rectal afferents were both significantly reduced in ls/ls mice.