Figure 4. Smooth muscle contraction bioassay.

(A) Guinea pig ileum samples were pre-incubated with buffer (solid line) or 1 µM AnSt-D7L1 (dotted line) and contraction was induced by 0.1 µM LTC₄ (L), as indicated by the far left hand arrow, in both control and experimental preparations. Since in the presence of AnSt-D7L1 no contraction was observed after first LTC₄ addition, further successive additions of 0.1 µM LTC₄ were made only to this preparation (dotted line), as indicated by additional arrows. (B) Rat aorta samples were pre-incubated with buffer (solid line) or AnSt-D7L1 (dotted line) and the effect of addition of 0.1 µM U46619 (U) was recorded. Since there was no contraction in the presence of the AnSt-D7L1 after the first addition, further additions of 0.1 µM U46619 were made only to the preparation incubated with protein, as indicated by additional arrows. (C) The ability of AnSt-D7L1 to reverse contraction induced by U46619 was tested by pre-contacting rat aorta samples with 1 µM U46619 (as indicated by the letter “U”). After the plateau was achieved, in the experimental sample (dotted line) 0.1 µM of AnSt-D7L1 was added (indicated by D7 in the figure), which caused relaxation of the sample. In order to show that the muscle was still functional, 3 µM phenylephrine was added (indicated by PE). A control (solid line) experiment was performed without addition of protein or PE in order to show that in the absence of AnSt-D7L1 contraction lasts throughout the experiment.