Purification, structural characterization, and cardiovascular activity of cod bradykinins

Area of Science:

• Comparative physiology
• Marine biology
• Biochemistry

Background:

• Bradykinin (BK) is a peptide hormone involved in various physiological processes, including blood pressure regulation.
• Understanding BK receptor subtypes and their functions across different species is crucial for comparative pharmacology.

Purpose of the Study:

• To identify and characterize bradykinin peptides in Atlantic cod (Gadus morhua).
• To investigate the physiological effects of these peptides on cardiovascular parameters in cod.
• To compare the binding properties of cod BK receptors with mammalian subtypes.

Main Methods:

• Plasma incubation with trypsin to generate peptides.
• Synthesis of identified cod bradykinin peptides.
• Intra-arterial injections into conscious cod to measure ventral aortic pressure and heart rate.
• Administration of pharmacological agents (prasozin, enalapril) to assess mediating pathways.

Main Results:

• Two peptides, [Trp5,Leu8]bradykinin (cod BK) and [Arg0,Trp5,Leu8]bradykinin (cod [Arg0]BK), were identified.
• Cod [Arg0]BK demonstrated potent pressor and heart rate increasing effects, approximately 10 times more potent than cod BK.
• Mammalian BK and cod des-Arg9,[Arg0]BK had no significant cardiovascular effects.
• The pressor response to cod [Arg0]BK was modulated by prasozin and enalapril, suggesting involvement of catecholamines but not the renin-angiotensin system.

Conclusions:

• Atlantic cod possess unique bradykinin peptides and receptors distinct from mammalian B1 and B2 subtypes.
• Cod [Arg0]BK elicits significant cardiovascular responses in cod, mediated partly by catecholamines.
• These findings contribute to understanding the evolution and diversity of the kinin-peptide system in vertebrates.