Purification and biological activity of alligator bradykinin

Abstract

Incubation of plasma form the alligator (Alligator mississipiensis) with glass beads in the presence of a kininase inhibitor resulted in the activation of the kallikrein-kinin system and generation of bradykinin-like immunoreactivity. The kinin peptides were purified to homogeneity and were shown to comprise [Thr6]-bradykinin and des-Arg9[Thr6]bradykinin in the molar ratio of approximately 10:1. Bolus injections of synthetic [Thr6]bradykinin into the jugular vein of the anesthetized alligator resulted in a dose-dependent decrease in mean arterial blood pressure. The minimum dose of kinin producing a significant fall in pressure was 0.07 micrograms/kg body wt and the maximum response (25 +/- 6% fall; mean +/- SD, n = 8) was produced by a dose of 0.56 micrograms/kg body wt. The dose producing a half-maximum response was 0.19 +/- 0.08 micrograms/kg. The data indicate that alligator plasma contains all the components of the kallikrein-kinin system found in mammals and suggest that the system may be of physiological importance in the regulation of cardiovascular function in these reptiles.

Cardiovascular actions of rattlesnake bradykinin ([Val1,Thr6]bradykinin) in the anesthetized South American rattlesnakeCrotalus durissus terrificus

“…The primary structure of BK also varies among other groups of reptiles (reviewed in 6). Treatment of plasma from the alligator (A. mississipiensis) and the turtle (T. scripta) with glass beads in the presence of a kininase inhibitor generated [Thr 6 ]BK (4,8). In contrast, all attempts to generate BK in the plasma of lizards and snakes through contact with a charged surface have been unsuccessful, suggesting that their blood does not contain a component analogous to mammalian factor XII.…”

Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures

“…In contrast to mammals, the role of humoral and local factors in cardiovascular control remains largely unknown in reptiles. Recent studies, nevertheless, indicate that the pulmonary circulation is much less responsive to humoral and local factors than the systemic circulation (8,9,11,16,35,40).Lung structure and heart morphology vary substantially among reptiles. Most snakes and many lizards have unicameral and simple lungs, whereas the multicameral lungs in turtles, varanid lizards, and crocodilians are more complex and compartmentalized (26,31,32,34).…”

“…In contrast to mammals, the role of humoral and local factors in cardiovascular control remains largely unknown in reptiles. Recent studies, nevertheless, indicate that the pulmonary circulation is much less responsive to humoral and local factors than the systemic circulation (8,9,11,16,35,40).…”

Purification of a vasoactive peptide related to lysyl‐bradykinin from trout plasma

“…As shown in Table I, trout lysyl-bradykinin shows two substitutions compared with human kallidin (Phe6--->Trp and Phe9-->Leu). The peptide shares with chicken bradykinin (ornitho-kinin) [1] the presence of a penultimate leucine residue but, unlike chicken and reptilian [2,3] bradykinins, contains a serine rather than a threonine residue. Although a peptide related to mam- Table I A comparison of the amino acid sequences of peptides related to trout lysyl-bradykinin malian lysyl-bradykinin rather than to bradykinin was isolated in the present study, the peptide was generated under non-physiological conditions i.e.…”

“…In the chicken, treatment of plasma kininogen with bovine plasma kallikrein generates [Thr6,Leu8]bradykinin (ornitho-kinin) [1]. Activation of endogenous kallikrein by incubation of plasma from the turtle [2] and alligator [3] with glass beads generates [Thr6]bradykinin. Synthetic replicates of the avian and reptilian kinins show potent vasodilator activity in their species of origin.…”