[Microcirculation of the liver in hemorrhagic shock in the rat and its significance for energy metabolism and function].
BACKGROUND
Shock induced microcirculatory failure is proposed to be causative for the impairment of hepatic function, which contributes to the development of multiple organ failure. In order to quantify the interrelation between hepatic microcirculatory disturbances and organ dysfunction, we have analyzed hepatic microcirculation (in vivo microscopy), energy metabolism (ketone body ratio) and liver excretory function (bile flow) during hemorrhagic shock in rats.


METHODS
Under chloralose anesthesia and mechanical ventilation Sprague-Dawley rats (n = 6) were laparotomized and the left liver lobe was exteriorized for in vivo fluorescence microscopy. Sinusoidal perfusion was assessed after i.v. injection of Na-fluorescein (2 mumol.kg-1), in vivo staining of white blood cells by Rhodamin-6G (0.1 mumol.kg-1 i.v.) enabled for analysis of leukocyte-endothelium interaction. Erythrocyte flux was measured by means of laser Doppler flowmetry. Hepatic function was estimated by measurement of bile flow via cannulation of the common bile duct. Ketone body ratio (acetoacetate/beta-hydroxybutyrate, Ac-Ac/beta-OHB) was measured spectrophotometrically from arterial blood and served as indicator of hepatic energy metabolism (n = 12). After baseline recordings hemorrhagic shock (MAP: 40 mmHG) was induced by blood withdrawal and maintained for a total of 2 h. Measurements were performed during baseline as well as 1 h and 2 h after induction of hemorrhage.


RESULTS
After 1 h and 2 h of hemorrhagic shock sinusoidal perfusion was found markedly impaired (p < 0.05) from 100% (baseline) to 78.3 +/- 2.4% and 60.9 +/- 13.4%, accompanied by a significant fall of erythrocyte flux to 52 +/- 2% and 46 +/- 4% (p < 0.05). Leukocyte velocity was significantly (p < 0.05) reduced both in sinusoids and in postsinusoidal venules, while leukocyte adherence to the endothelial lining cells was found increased (sinusoids: 183.2 +/- 55.6% and 178.8 +/- 39.0% (p < 0.05); postsinusoidal venules: 232.4 +/- 43.1% and 297.6 +/- 65.8% (p < 0.05)). In addition, 2 h of hemorrhagic shock caused an increase of beta-OHB, while Ac-Ac levels remained unchanged. This resulted in a significant reduction of ketone body ratio. Concomitantly, bile production was significantly decreased from 20.8 +/- 2.9 microliters.min-1 during control to 6.1 +/- 1.0 microliter.min-1 after 2 h of shock (p < 0.05). The alteration of energy metabolism and the impairment of bile flow correlated significantly (p < 0.01) with the extent of microcirculatory disturbances.


CONCLUSIONS
Liver microcirculation in hemorrhagic shock is characterized by sinusoidal perfusion failure with a reduction of erythrocyte flux, leukocyte velocity and enhancement of leukocyte adherence to the microvascular endothelial lining. Correlation of the impairment of energy metabolism and liver dysfunction with these microcirculatory disturbances may indicate their crucial role in the development of shock-induced organ failure.
Vollmar
B
B
Institut für Chirurgische Forschung, Ludwig-Maximilians-Universität München.
Lang
G
G
Post
S
S
Menger
M D
MD
Messmer
K
K
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D007657:Ketone Bodies / Q000097:blood; D008099:Liver / Q000098:blood supply*; D008111:Liver Function Tests; D008297:Male; D008833:Microcirculation / Q000503:physiopathology; D008856:Microscopy, Fluorescence; D009102:Multiple Organ Failure / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012771:Shock, Hemorrhagic / Q000503:physiopathology*
D007657:Ketone Bodies
Die Mikrozirkulation der Leber im hämorrhagischen Schock der Ratte und ihre Bedeutung für Energiestoffwechsel und Funktion.