<p>The contractile response to ACh in ileal muscle from the ANP+saline rats were lower than that obtained from the control+saline group at 24 h(*; <i>P</i> = 0.026; <i>A, C</i>). No significant difference were observed between the ANP+octreotide groups (24 h, 48 h and 72 h) and the control+octreotide group (<i>C</i>). The response to ACh in ANP+octreotide group was much higher than the ANP+saline group at 24 h (**; <i>P</i> = .002; n = 8; <i>A, C</i>). No difference in response to l-NNA was found between any of the ANP+saline groups (24 h, 48 h and 72 h) and the control+saline group or between any of the ANP+octreotide groups (24 h, 48 h and 72 h) and the control+octreotide group (<i>B, D</i>). The response to l-NNA in the ANP+octreotide group was higher than the ANP+saline group at 24 h (<i>P</i> = .053; n = 8; <i>B, D</i>). Data are expressed as means ± SEM. (*, <i>P</i><.05; **, <i>P</i><.01).</p