Fig. 1. Gel permeation chromatography on a Sephadex G-25 column of kallikrein-treated skate plasma after partial purification on Sep-Pak cartridges. Fractions denoted by the bar produced relaxation of rings of vascular smooth muscle from the skate ventral aorta and were pooled and subjected to reversed phase HPLC. The arrow denotes the elution volume of mammalian bradykinin.

Fig. 2. Reversed-phase HPLC on a semipreparative Vydac C₁₈ column of pooled fractions from gel permeation chromatograhy associated with vasorelaxant activity. The peak denoted by (+) contained material that produced relaxation of vascular rings from the ventral aorta. The dashed line shows the concentration of acetonitrile in the eluting solvent.

Fig. 3. Purification to near homogeneity of skate BK on an analytical Vydac C₄ reversed-phase HPLC column. Peaks 1–3 were analyzed by mass spectrometry and peak-3 contained the bioactive peptide.

Fig. 4. Concentration-response curves showing the myoactivity of skate BK (●—●) and skate [Arg⁹]BK (○—○) on isolated vessels from; (a) the mesenteric artery, (b) the 1st branchial artery; and (c) the ventral aorta. Data (mean ± S.E.M.; n = 6) are expressed as percent of the constriction produced by 60 mM KCl. ^**p < 0.01 and ^γγp < 0.01 vs baseline values for skate BK and skate [Arg⁹]BK, respectively.

Fig. 5. Concentration-response curves showing the activity of skate BK (●—●) and skate [Arg⁹]BK (○—○) on isolated intestinal smooth muscle ring preparations. Values are expressed as a percentage of the maximum force following addition of 10⁻⁵ M ACh. Mean ± S.E.M.; n = 8, ^*p < 0.05.

A comparison of the primary structures of the bradykinin-related peptides isolated from fish with mammalian bradykinin

(–) denotes residue identity with the mammalian peptide.