Mechanisms of Decreased Plasma Volume During Acute Psychological Stress and Postural Change in Humans
Abstract
Recent research has noted that acute psychological stress can lead to rapid and significant decreases in plasma volume in humans. However, this research has not conclusively identified the underlying mechanisms for stress-induced plasma volume changes. The present research examined the effects of psychological stress on plasma volume and the relationship of these changes to increases in blood pressure, red blood cell mass, and red blood cell fluid volume. The time course of plasma volume changes following psychological stress was also assessed. Plasma volume change was assessed using mass densitometry techniques, thus allowing for direct assessment of plasma volume. In this study, 10 men and 10 women were evaluated for their hematologic and hemodynamic responses in response to a stressful math task and to postural change (standing). A no-stress control group of 10 men and 10 women performed a nonstressful reading task and the standing task. The two tasks (mental arithmetic or reading, and standing) were counterbalanced within each group. Results indicated that psychological stress and posture change produced significant decreases in plasma volume and significant increases in blood pressure, blood and plasma density, and total plasma protein. No gender differences were found for lean body weight-corrected changes in plasma volume, blood pressure, or any other hematologic factor during any of the tasks. A reliable association was observed between blood pressure responses and plasma volume changes during psychological stress, and plasma volume returned to baseline within 12 minutes following mental arithmetic. The present results suggest that an important mechanism for psychological stress-induced decreases in plasma volume is increased blood pressure leading to increased transvascular fluid shifts from the vascular system into the interstitial spaces.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 14, 1993
- Accession Number
- AD1011292
Entities
People
- Stephen Patterson
Organizations
- Uniformed Services University of the Health Sciences