Purification and cardiovascular activity of [Met1, Met5]-bradykinin from the plasma of a sturgeon (Acipenseriformes).
The sturgeons (Order Acipenseriformes) are extant representatives of a group of primitive Actinopterygian (ray-finned) fish that probably shared a common ancestor with present-day teleosts. Incubation of heat-denatured plasma from a sturgeon (a hybrid of the shovelnosed sturgeon Scaphirhynchus platorynchus and the pallid sturgeon Scaphirhynchus albus) with either trypsin or porcine pancreatic kallikrein generated bradykinin-like immunoreactivity. The primary structure of sturgeon bradykinin was established as Met-Pro-Pro-Gly-Met-Ser-Pro-Phe-Arg. This amino acid sequence contains two amino acid substitutions (Arg1 --> Met and Phe5 --> Met) compared with mammalian bradykinin. Bolus injections of synthetic sturgeon bradykinin in doses as low as 1 pmol/kg into the dorsal aorta of unanesthetized sturgeon resulted in an immediate and significant fall in arterial blood pressure with a maximum depressor response at 300 pmol/kg. Thus, the cardiovascular response of the sturgeon to bradykinin resembles more closely the response of mammals rather than the predominantly pressor response seen in teleost fish. Sturgeon bradykinin produced a strong and concentration-dependent (EC50 = 4.7 +/- 0.7 x 10(-10) M) relaxation of rings of vascular tissue from the sturgeon ventral aorta that had been pre-contracted with acetylcholine. The data indicate that sturgeon tissues are particularly responsive to native bradykinin and suggest that the kallikrein-kinin system may have evolved before the appearance of the neopterygians (gars, bowfin and teleosts).
Li
Z
Z
Regulatory Peptide Center, Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA.
Smith
M P
MP
Duff
D W
DW
Barton
B A
BA
Olson
K R
KR
Conlon
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D002317:Cardiovascular Agents / Q000097:blood* / Q000302:isolation & purification / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019143:Evolution, Molecular; D005399:Fishes; D066298:In Vitro Techniques; D016234:Kallikrein-Kinin System; D008969:Molecular Sequence Data; D011863:Radioimmunoassay; D017386:Sequence Homology, Amino Acid
D002317:Cardiovascular Agents; C113887:bradykinin, Met(1,5)-; D001920:Bradykinin