Sensitivity differences to 5-HT and carbachol in subsections of the isolated rat stomach fundus strip: an improved...

The rat stomach fundus strip has often been used as a sensitive assay of pharmacological activity at 5-HT receptors. In the present study, we describe an improved preparation based on the finding that the majority of the contractile response to 5-HT and carbachol was present in one particular longitudinal quartile of the tissue. The fundi were dissected into four anatomically consistent sections and labelled accordingly (left ventral = LV; right ventral = RV; left dorsal = LD; right dorsal = RD). A distinct pattern of responsiveness (contraction) to 5-HT and carbachol was observed. For carbachol, the maximum contraction ratios of the sections (LV:LD:RV:RD) were 7.2(+/-0.8):5.8(+/-1.4):4.2(+/-0.46):3.0 (+/-0.22), respectively. For 5-HT, the differences were more pronounced with maximum contraction ratios of 5.6 (+/-0.94): 3.6(+/-0.58):1.4(+/-0.30):1.6(+/-0.22), respectively. When the sections were dissected along the submucosa, the mucosal section responded to carbachol and 5-HT, while the muscularis externa did not respond to these agonists. Selection of the LV section allowed the use of smaller bath volumes, and subsequent bisection facilitated the design of more effective paired experiments.