Effect of Ca2+-free solutions containing 0.5 mmol/L EGTA (0Ca), verapamil (V, 100 nmol/L), thapsigargin (T, 100 nmol/L), ryanodine (R, 100 nmol/L), staurosporine (St, 100 nmol/L), and U 73122 (U, 100 nmol/L) on contractions caused by SP (100 nmol/L) in longitudinal (A) and circular (B) smooth muscle of rabbit duodenum, jejunum, and ileum. Columns indicate the mean values of integrated mechanical activity (% of SP), and vertical bars indicate SEM. bP<0.05, cP<0.01. Numbers in brackets indicate the number of segments.