Biphasic, organ-specific, and strain-specific accumulation of platelets induced in mice by a lipopolysaccharide from Escherichia coli and its possible involvement in shock

Abstract

Platelets contain a large amount of 5-hydroxytryptamine (5HT, serotonin). Intravenous injection into BALB/c mice of a Boivin's preparation of lipopolysaccharide (LPS) from Escherichia coli induced rapid 5HT accumulation in the lung (within 5 min) and slow 5HT accumulation in the liver (2 to 5 h later). The rapid response required high doses of LPS (more than 0.1 mg/kg). On the basis of 5HT measurements, 70% or more of the platelets which disappeared from the blood appeared to have accumulated rapidly in the lung, and a large number of platelets were found there by electron microscopy. A shock, which was manifested by crawling, convulsion, or prostration, followed shortly after the rapid accumulation of 5HT in the lung. On the other hand, the slow accumulation of 5HT in the liver could be induced by much lower doses of LPS (1 microg/kg or less), even when given by intraperitoneal injection. This 5HT accumulation appears to be a reflection of platelet accumulation in the liver (Y. Endo and M. Nakamura, Br. J. Pharmacol. 105:613-619, 1992). The combination of a low dose of LPS with D-galactosamine amplified the hepatic accumulation of 5HT, and the mice developed a severe hepatic congestion resulting in death. The rapid response was not induced at all in C3H/HeN mice. These results and comparison with other LPS preparations indicate that some component(s) of LPS from E. coli induces a biphasic, organ-specific and strain-specific accumulation of platelets, and it is proposed that this effect is involved in the development of shock.