Bioactivity of postshock mesenteric lymph depends on the depth and duration of hemorrhagic shock
Tomohiko Masuno1, Ernest E Moore, Aaron M Cheng
1Department of Surgery, Denver Health Medical Center and University of Colorado Health Sciences Center, Denver, CO 80204, USA.
Abstract:
Mesenteric hypoperfusion due to circulatory shock is a key event in the pathogenesis of subsequent distant organ injury. Postshock mesenteric lymph (PSML) has been shown to contain proinflammatory mediators elaborated from the ischemic gut. We hypothesize that the relative bioactivity of PSML depends on the depth and duration of circulatory shock. To first determine the timing of PSML bioactivity, we subjected rats to hemorrhagic shock (30 mm Hg x 45 min) and then resuscitation with 50 vol% of shed blood and normal saline (4x shed blood) over 2 h. Mesenteric lymph was collected hourly up to 6 h after shock. Superoxide release was measured from human neutrophils (polymorphonuclear neutrophils [PMNs]) incubated with lymph fractions collected from each of the hourly time points. Rats were then subjected to four different shock variations: (1) 30 mm Hg x 45 min, (2) 30 mm Hg x 15 min, (3) 45 mm Hg x 45 min, and (4) 45 mm Hg x 15 min, and were resuscitated. PSML flow depends on depth of shock, but not duration of shock or resuscitation volume. Maximal PSML bioactivity, as measured by PMN priming for the respiratory burst, occurred during the third postshock hour, which correlated with peak lymph flow rate. PSML bioactivity was greatest with 30 mm Hg x 45 min, followed by 30 mm Hg x 15 min, 45 mm Hg x 45 min, and 45 mm Hg x 15 min. Hemorrhagic shock provokes the release of bioactive agents in PSML that is dependent on both depth and duration of shock.
Insights
Post-shock mesenteric lymph (PSML) contains inflammatory mediators. Its bioactivity, measured by neutrophil superoxide release, depends on circulatory shock severity and duration, peaking in the third hour post-shock.
Area of Science:
- Physiology
- Immunology
- Gastroenterology
Background:
- Circulatory shock can cause mesenteric hypoperfusion, leading to distant organ injury.
- Post-shock mesenteric lymph (PSML) contains proinflammatory mediators from ischemic gut.
- The bioactivity of PSML may vary with shock depth and duration.
Purpose of the Study:
- To investigate the timing and bioactivity of PSML following hemorrhagic shock.
- To determine how shock depth and duration influence PSML's inflammatory potential.
Main Methods:
- Rats underwent hemorrhagic shock (30 mm Hg x 45 min) followed by resuscitation.
- Mesenteric lymph was collected hourly for 6 hours post-shock.
- PSML bioactivity was assessed by measuring superoxide release from human neutrophils (PMNs).
- Different shock variations (depth and duration) were tested.
Main Results:
- PSML flow was influenced by shock depth but not duration or resuscitation volume.
- Maximal PSML bioactivity, indicated by PMN priming for respiratory burst, occurred 3 hours post-shock, correlating with peak lymph flow.
- The most potent PSML bioactivity was observed with 30 mm Hg x 45 min shock, followed by 30 mm Hg x 15 min, 45 mm Hg x 45 min, and 45 mm Hg x 15 min.
Conclusions:
- Hemorrhagic shock releases bioactive agents into PSML.
- PSML bioactivity is dependent on both the depth and duration of circulatory shock.
- These findings highlight PSML's role in post-shock inflammatory responses.
