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Mesenteric vasoconstriction in response to hemorrhagic shock.
1Department of Anesthesiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-4685, USA.
Shock (Augusta, Ga.)
|April 25, 2000
Summary
Hemorrhagic shock causes selective mesenteric ischemia via disproportionate mesenteric vasospasm. The renin-angiotensin axis primarily mediates this response, similar to cardiogenic shock.
Area of Science:
- Cardiovascular Physiology
- Gastrointestinal Physiology
Background:
- Cardiogenic shock causes mesenteric ischemia via the renin-angiotensin axis.
- Understanding neurohumoral mechanisms in hypovolemic shock is crucial.
Purpose of the Study:
- Characterize systemic and mesenteric hemodynamic responses to hypovolemic shock.
- Identify neurohumoral control mechanisms of mesenteric ischemia in hemorrhagic shock.
Main Methods:
- Graded hemorrhage (12.5-50% blood volume) in swine.
- Measured systemic and mesenteric pressures/flows; calculated resistances.
- Repeated experiments after alpha-adrenergic, vasopressin, or renin-angiotensin blockade.
Main Results:
- Hemorrhagic shock induced graded systemic hypotension and peripheral vasoconstriction.
- Disproportionate mesenteric vasoconstriction and ischemia occurred.
- Mesenteric ischemia was blocked by renin-angiotensin axis blockade (enalapril), but not alpha-adrenergic or vasopressin blockade.
Conclusions:
- Hemorrhagic shock, like cardiogenic shock, causes selective mesenteric ischemia.
- Disproportionate mesenteric vasospasm is primarily mediated by the renin-angiotensin axis.