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Endomorphin 1 and 2, endogenous ligands for the mu-opioid receptor, decrease cardiac output, and total peripheral
H C Champion1, J E Zadina, A J Kastin
1Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA. champion@mailhost.tcs.tulane.edu
Peptides
|January 1, 1997
Summary
Endomorphin 1 and 2, new mu-opioid receptor ligands, significantly lower blood pressure and heart rate in rats. These findings highlight their potent vasodilator activity in the systemic vascular bed.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
- Neuroendocrinology
Background:
- Endomorphin 1 and 2 are newly identified endogenous ligands for the mu-opioid receptor.
- Understanding their physiological effects is crucial for elucidating opioid receptor function.
Purpose of the Study:
- To investigate the cardiovascular effects of intravenous endomorphin 1 and 2 in the rat systemic vascular bed.
- To compare these effects with other vasoactive substances like nociceptin/OFQ, isoproterenol, and CGRP.
Main Methods:
- Intravenous administration of varying doses of endomorphin 1 and 2 in anesthetized rats.
- Monitoring of systemic arterial pressure, heart rate, cardiac output, and total peripheral resistance.
- Comparative administration of nociceptin/OFQ, isoproterenol, and CGRP.
Main Results:
- Endomorphin 1 and 2 induced dose-dependent decreases in systemic arterial pressure.
- These hypotensive effects were accompanied by reductions in heart rate, cardiac output, and total peripheral resistance.
- Nociceptin/OFQ produced similar cardiovascular effects, while isoproterenol and CGRP caused vasodilation with increased heart rate and cardiac output.
Conclusions:
- Endomorphin peptides possess significant vasodilator activity in the rat systemic vascular bed.
- The observed vasodilation is associated with a decrease in heart rate and cardiac output, distinct from other tested agents.