Modulation of Crayfish Hearts by FMRFamide-related Peptides

Area of Science:

• Neuroendocrinology
• Comparative Physiology
• Marine Biology

Background:

• FMRFamide-related peptides (FaRPs) are a diverse group of neuropeptides found throughout the animal kingdom.
• These peptides are known to modulate various physiological processes, including cardiac function.

Purpose of the Study:

• To investigate the effects of specific FMRFamide-related peptides on the cardiac activity of crayfish (Procambarus clarkii).
• To determine the structure-activity relationships of these peptides in modulating heart rate and contraction amplitude.

Main Methods:

• Isolated crayfish hearts were perfused with varying concentrations of different FMRFamide-related peptides.
• Heart rate and contraction amplitude were measured to quantify the peptides' effects.

Main Results:

• Lobster peptides F1 and F2 significantly increased heart rate and amplitude at nanomolar concentrations.
• Native FMRFamide and FLRFamide showed similar but weaker cardioexcitatory effects at higher concentrations.
• SchistoFLRFamide and leucomyosuppressin exhibited potent cardiac inhibition at nanomolar to micromolar concentrations.
• Amino-terminal extensions were found to be crucial for both the enhanced excitatory and inhibitory actions of these peptides.

Conclusions:

• Crayfish hearts are sensitive to a range of FMRFamide-related peptides with diverse effects.
• The structure of the amino-terminal extensions significantly influences the potency and type of cardiac modulation.
• Further research is needed to elucidate the specific receptor sites and mechanisms underlying these observed effects.