Figure 1  .

Concentration dependent relaxation of human colon by isoprenaline. (A) Representative tracings; values are mol/l of isoprenaline. (B) Concentration-response curves in circular smooth muscle with and without added β adrenoceptor antagonists; values are mean (SEM) of 5-10 preparations from different patients. (C) Concentration-response curves in longitudinal smooth muscle with and without added β adrenoceptor antagonists; values are mean (SEM) of 5-10 preparations from different patients.