This study aimed to establish an allometric scaling relationship between the frequency of intestinal contractions and body mass of different mammalian species. The frequency of intestinal contractions of rabbit, guinea pig, rat and mouse were measured using an isolated organ system. The isolated rings were prepared from proximal segments of jejunums and the frequency of contractions was recorded by an isometric force procedure. The coefficients of the obtained allometric equation were ascertained by computation of least squares after logarithmic transformation of both body mass and frequency. Significant differences (𝑝 <0.001) were shown in the frequency of contractions between different species. The highest frequency that corresponded to the mice was 57.7 min⁻¹ and the 95% confidence interval (CI) ranged from 45.4 to 70, while rabbits showed the lowest frequency (12.71 min⁻¹, CI: 8.6–16.8). Logarithms of frequency were statistically proportional to logarithms of body mass (r=0.99; 𝑝 < 0.001). The data fitted an equation 𝐹 = 18:51 𝐵^-0.31 and the 95% confidence interval of the exponent ranged from −0.30 to −0.32. The results of this study suggest that it is probably possible to extrapolate the intestinal contraction frequency of other mammalian species by the means of allometry scaling.

The enteric nervous system (ENS) arises from the enteric neural crest-derived cells (ENCCs), and many molecules and biochemical processes may be involved in its development. This study examined the effects of modulating embryonic nitric oxide (NO) activity on the intestinal motility induced by ENS. One-hundred-and-twenty fertilized chicken eggs were assigned to three main groups and incubated at 37°C and 60% humidity. The eggs were treated with 𝑁^𝐺-nitro-L-arginine methyl ester (L-NAME), sodium nitroprusside (SNP), L-arginine (L-Arg) or vehicle from days 3 (1st group), 7 (2nd group) and 10 (3rd group) of incubation and continued up to day 18. On day 19, the embryos were sacrificed, the jejunal and colorectal segments were taken and the intestinal motility was assessed using isolated organ system. The intestinal motility was recorded normally and following cholinergic, adrenergic and non-adrenergic non-cholinergic (NANC) stimulations. The ENS structure was assessed by immunohistochemistry (IHC) using glial fibrillary acidic protein (GFAP). Rhythmic intestinal contractions were seen in all treatment groups, but inhibition of NO in the L-NAME-treated embryos caused significant decrease (𝑝 < 0.01) in the frequency and amplitude of the contraction. The responsiveness to adrenergic, cholinergic and NANC stimulations was also significantly decreased (𝑝 <0.05). The GFAP expression was significantly (𝑝 < 0.05) reduced in the L-NAME-treated embryos. This study showed that the inhibition of NO caused a deficient development of the ENS, leading to a decrease in the frequency and amplitude of the intestinal contractions and reduced the responsiveness to adrenergic, cholinergic and NANC signalling.