Impact of shock and fluid resuscitation on the morphology and apoptosis of bone marrow: an experimental study.
BACKGROUND
We hypothesized that bone marrow failure after hemorrhagic shock might be secondary to impaired apoptosis regulation. Our objective was to assess the morphologic alterations and the rate of apoptosis in bone marrow after hemorrhagic shock and resuscitation.


METHODS
Under pentobarbital anesthesia, Wistar rats (n = 70) underwent femoral vessel cannulation. The hemorrhagic shock model involved a controlled retrieval of blood, maintaining mean blood pressure at 40 +/- 5 mm Hg during 50 minutes. During the resuscitation period, lactated Ringer's (twice the blood volume retrieved, group LR) or NaCl 7.5% (4 mL/kg, group HS) was infused, followed by the previously retrieved blood. Bone marrow was collected through left femoral puncture. Morphology was assessed by Leishmann-stained smears, and apoptosis was assessed through terminal deoxynucleotide transferase-mediated dUTP nick-end labeling assay. Analysis of variance and Tukey's test were applied for statistical treatment, considering p < 0.05 as significant.


RESULTS
LR animals presented a statistically significant decrease in the lymphocytic series (LR, 24.2 +/- 4.2%; Sham, 55.1 +/- 6.6%), together with an increase in the percentage of granulocyte (LR, 51.4% +/- 2.3%; Sham, 31.5 +/- 2.9%) and monocyte precursors (LR, 7.3 +/- 1.3%; Sham, 3.3 +/- 1.1%), detected 72 hours after shock (p < 0.05). Both LR and HS groups presented a significant increase in apoptosis, when compared with the sham group (LR, 13.1 +/- 0.5%; HS, 12.2 +/- 0.7%; Sham, 6.8 +/- 0.4%). The alterations detected in the bone marrow morphology of LR group were not observed in HS animals.


CONCLUSIONS
There was an increase in bone marrow apoptosis after hemorrhagic shock. The type of resuscitation scheme used did influence bone marrow morphology.
Parreira
José Gustavo
JG
Emergency Service, Department of Surgery, Santa Casa Medical School, and Heart Institute (InCor), LIM11, Sao Paulo, Brazil. jgparreira@oul.com.br
Rasslan
Samir
S
Poli de Figueiredo
Luiz F
LF
Bortolheiro
Thereza Christina
TC
Sinosaki
Sueli
S
Hardt
Daniela
D
Langui
Margareth Yada
MY
Rocha
Milene N
MN
Longui
Carlos Alberto
CA
Chiattone
Carlos
C
Rocha e Silva
Maurício
M
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis; D001794:Blood Pressure; D001854:Bone Marrow Cells / Q000166:cytology; D001855:Bone Marrow Diseases / Q000097:blood / Q000209:etiology / Q000473:pathology; D001856:Bone Marrow Examination; D004253:DNA Nucleotidylexotransferase; D004195:Disease Models, Animal; D004906:Erythrocyte Count; D005440:Fluid Therapy / Q000379:methods*; D006098:Granulocytes / Q000166:cytology; D007108:Immune Tolerance; D020287:In Situ Nick-End Labeling; D007552:Isotonic Solutions / Q000627:therapeutic use; D007958:Leukocyte Count; D008214:Lymphocytes / Q000166:cytology; D008297:Male; D009000:Monocytes / Q000166:cytology; D051381:Rats; D017208:Rats, Wistar; D012151:Resuscitation / Q000379:methods*; D000077325:Ringer's Lactate; D012771:Shock, Hemorrhagic / Q000150:complications / Q000628:therapy; D013997:Time Factors
D007552:Isotonic Solutions; D000077325:Ringer's Lactate; D004253:DNA Nucleotidylexotransferase