Acute circulatory collapse caused by platelet-activating factor (PAF-acether) in dogs

Area of Science:

• Physiology
• Pharmacology
• Pathophysiology

Background:

• Platelet-activating factor (PAF-acether) is a potent lipid mediator.
• The role of PAF-acether in inducing shock and circulatory collapse requires further elucidation.

Purpose of the Study:

• To investigate the potential of synthetic PAF-acether as a shock inducer in a canine model.
• To characterize the physiological and hemodynamic changes induced by PAF-acether administration.

Main Methods:

• Intravenous injection of synthetic PAF-acether (9 or 36 nmol/kg) into anesthetized dogs.
• Monitoring of systemic and regional hemodynamics, cardiac output, heart rate, blood pressure, and hematocrit.
• Measurement of plasma volume, femoral artery blood flow, and blood gas analysis.

Main Results:

• Low-dose PAF-acether (9 nmol/kg) induced transient hypertension, increased TXB2 and 6-keto-PGF1α, and caused significant hypotension, reduced cardiac output, plasma volume, and femoral blood flow, with increased hematocrit.
• High-dose PAF-acether (36 nmol/kg) led to reduced coronary blood flow, diminished myocardial oxygen consumption, increased oxygen extraction, metabolic acidosis, and mortality in some animals.
• Observed changes mirrored acute circulatory collapse, indicating distributive and hypovolemic shock features.

Conclusions:

• Synthetic PAF-acether acts as a potent shock inducer in dogs.
• PAF-acether administration elicits profound hemodynamic alterations consistent with circulatory collapse.
• These findings suggest PAF-acether may be an endogenous mediator in both early and late stages of shock.