Intermedin 1-53, a peptide in the calcitonin gene-related peptide family, significantly improved survival and cardiac function in septic shock rats through Rho kinase and BKCa channel pathways.
Survival improvedBoth early and late administration of intermedin 1-53 significantly improved survival in septic shock rats, with the peptide rescuing cardiac contractility and tissue oxygen delivery
What the researchers found
IMD1-53 (0.5 μg/kg) administered to septic shock rats demonstrated:
• Significantly improved animal survival with both early (immediately after CLP) and late (12 hours after CLP) administration
• Increased cardiac contractility and function
• Improved tissue perfusion and oxygen delivery
• Early administration produced better results than late administration
Mechanistically, IMD1-53 acted through two pathways:
1. Rho kinase/TnI pathway: IMD1-53 increased Rho kinase expression in cardiac muscle and inhibited troponin I (TnI) phosphorylation
2. BKCa channel pathway: IMD1-53 inhibited BKCa channel currents and reduced intracellular calcium concentration in cardiomyocytes
Both pathways were confirmed by pharmacological blockade — a Rho kinase inhibitor (Y-27632) or BKCa opener (NS1619) abolished IMD1-53's protective effects.
Why it matters
Septic shock kills millions worldwide, and cardiac dysfunction during sepsis is a major driver of mortality. Current treatments focus on antibiotics and fluid resuscitation but have limited ability to directly support the failing heart. A peptide-based therapy that can rescue cardiac function in sepsis — even when given late — could represent a genuine advance in critical care medicine.
How the study worked
Septic shock was induced in Sprague-Dawley rats using cecal ligation and puncture (CLP), a standard model. IMD1-53 was given at 0.5 μg/kg either immediately or 12 hours post-CLP. Outcomes included survival, cardiac papillary muscle contractility, cardiomyocyte function, tissue perfusion, and oxygen delivery. Pathway involvement was confirmed using pharmacological inhibitors. BKCa channel currents and intracellular calcium were measured electrophysiologically.
What this study cannot tell us
Conducted entirely in rats — septic shock pathophysiology and treatment responses can differ significantly in humans. The CLP model, while standard, may not replicate the complexity of clinical sepsis. A single dose (0.5 μg/kg) was tested; dose-response relationships are not established. No comparison to standard sepsis therapies. Long-term outcomes beyond survival were not assessed. The peptide's pharmacokinetics and stability in vivo were not characterized.
How to read the evidence
This is a preclinical study in a rat septic shock model with rigorous mechanistic dissection using pharmacological pathway blockade. While the experimental design is strong, all findings are in animals and have not been tested in humans. Preclinical sepsis studies have a historically poor translation rate to clinical success.
When this study was published
Published in 2016, this study provides foundational evidence for intermedin's role in septic cardiac protection. Since then, adrenomedullin (a related peptide) has advanced further in clinical sepsis research, though intermedin-specific clinical development appears limited.
The bigger picture
Intermedin belongs to the CGRP/adrenomedullin peptide superfamily, which has broad cardiovascular protective properties. While CGRP-blocking antibodies have become major migraine therapies, the protective arm of this peptide family — including intermedin and adrenomedullin — is being explored for critical illness. This study adds septic cardiomyopathy to the list of conditions where CGRP-related peptides show therapeutic potential, complementing their known roles in ischemia-reperfusion injury and heart failure.
Questions still open
- Can intermedin 1-53 or analogs be developed into a viable therapy for human septic cardiomyopathy?
- How does intermedin compare to adrenomedullin, which is already being explored clinically for sepsis?
- Would intermedin's cardiac effects complement existing sepsis treatments like vasopressors and antibiotics?
Common questions
What is intermedin and how is it related to CGRP?
Why does the heart fail during sepsis?
Read the original research
Beneficial Effect of Intermedin 1-53 in Septic Shock Rats: Contributions of Rho Kinase and BKCA Pathway-Mediated Improvement in Cardiac Function.
Shock (Augusta, Ga.), 46(5), 557-565
Citation
Zhu, Yu; Wu, Huiling; Wu, Yue; Zhang, Jie; Peng, Xiaoyong; Zang, Jiatao; Xiang, Xinming; Liu, Liangming; Li, Tao. (2016). Beneficial Effect of Intermedin 1-53 in Septic Shock Rats: Contributions of Rho Kinase and BKCA Pathway-Mediated Improvement in Cardiac Function.. Shock (Augusta, Ga.), 46(5), 557-565.