Fluid extravasation from spleen reduces blood volume in endotoxemia

Abstract

We recently demonstrated that fluid is filtered out of the splenic circulation and into the lymphatic system. The current experiments were designed to investigate the importance of this route of fluid extravasation in endotoxemia. Lipopolysaccharide (LPS) was infused into conscious intact and splenectomized rats (150 microg x kg(-1). h(-1) i.v. for 18 h). In the intact rats, mean arterial pressure (MAP) fell from 101+/-2.4 to 88+/-3.9 mm Hg (n = 7) and then stabilized at about 90 mm Hg. Hematocrit rose from 41+/-0.9 to 45+/-0.4% at 40 min, at which time plasma volume had fallen from 4.7+/-0.12 to 4.0+/-0.05 ml/100 g body wt. In the splenectomized rats MAP did not fall and hematocrit did not rise. There also was no change in plasma volume, i.e., splenectomy prevented the hypotension and hemoconcentration customarily induced by LPS. In a second series of experiments, splenic arterial and venous blood flows were simultaneously measured in anesthetized rats infused with LPS (150 microg x kg(-1) x h(-1)). LPS increased splenic fluid efflux. We conclude that during endotoxemia the initial fall in circulating blood volume may be attributed to fluid extravasation from the splenic vasculature.

Access to the Spleen Microenvironment through Lymph Shows Local Cytokine Production, Increased Cell Flux, and Altered Signaling of Immune Cells during Lipopolysaccharide-Induced Acute Inflammation

“…They have found that the spleen has a very high blood flow (∼8 ml/min/g) (20), and also that there is a significant arteriovenous volume difference that is filtered out of the blood into the lymphatic system (2,20). Such filtration is exaggerated during volume loading (2) and LPS infusion (21), favoring lymph formation even further in these conditions. In line with these observations, we found that spleen lymph accumulated avidly at a rate of ∼2 ml/min in control situation and increasing 8-fold this value 3 h after LPS exposure.…”

Role of spleen in integrated control of splanchnic vascular tone: physiology and pathophysiologyThis article is part of a Special Issue on Information Transfer in the Microcirculation.

“…We have shown that intrasplenic fluid extravasation plays a critical role in the early stages of endotoxemia-induced hypovolemia and hypotension (Andrew et al 2000;Andrew and Kaufman 2001a). Lipopolysaccharide (LPS) infusion, a model of endotoxemia, was shown in conscious rats to cause profound reductions in mean arterial pressure and plasma volume.…”

Long-term effects of repeated pregnancies (multiparity) on blood pressure regulation

“…A nonocclusive cannula (Silastic, ID: 0.51-mm, OD: 0.94-mm) was implanted into the inferior vena cava for drug infusion [15]. A pressure transmitter (PA-C40, Data Sciences International) was implanted in the abdominal aorta [2]. Animals were allowed to recover for one week from surgery and to regain their preoperative body weight.…”