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At least 109 records · Page 6Linked to original sources
PubMed1958

Studies on solute transfer in the vascular endothelium.

Barium chromate, Prussian blue, and cobalt-cobalticyanide can be precipitated in vivo in the endothelium of mesenteric vessels by injection of the appropriate anions into the blood stream, and topical application of the precipitating cations to the exposed mesenteries of mice and frogs. Precipitation in the endothelium occurs in the form of a diffuse fine punctate precipitate, and also as continuous lines demarcating endothelial cell outlines. A striking feature is the frequent occurrence of this type of precipitation in a tapering zone downstream from mural thrombi in the veins.

Animals↗
PubMed1957

The role of vasoconstriction in the local Shwartzman reaction.

The local Shwartzman reaction was provoked in the skin of the ear, hind leg, and costovertebral angle of the rabbit, as well as in the ventral abdominal skin. Certain adrenergic blocking drugs reduced the incidence of positive reactions when given prior to the provocative dose of bacterial polysaccharide. Epinephrine and other vasoconstrictor drugs administered intradermally into the prepared skin site produced typical hemorrhagic-necrotic lesions when the usual intravenous injection of polysaccharide was omitted. This reaction could be blocked by adrenergic blocking drugs, but appeared to be augmented by heparin or nitrogen mustard. A hypothesis has been developed to help explain the mechanism of the local Shwartzman reaction. Following the preparatory dose, tissue metabolic changes occur which lead to increased lactic acid production and render the area particularly susceptible to anoxia. Following the provocative dose, adrenergic vasoconstriction occurs. It is suggested that this vasoconstriction may be intensified at the prepared site by small residual amounts of the preparatory dose of polysaccharide which might potentiate the action of the epinephrine. The anoxia initiated by the vasoconstriction is prolonged and intensified by the formation of intravascular thrombi around clumps of leucocytes and platelets. This anoxia, superimposed on the local metabolic changes, leads to the characteristic lesion of hemorrhage and necrosis. Thus a combination of factors, all of causal importance and largely due to known pharmacologic properties of bacterial lipopolysaccharide, occur in specific sequence to lead to the classic local Shwartzman reaction.

Animals↗
PubMed1961

Pathogenesis of experimental shock. III. A lethal factor in the blood of rabbits following occlusion of the superior mesentric artery.

Donor rabbits were subjected to shock by occlusion of the superior mesenteric artery (SMAO shock). Portal blood was collected from these animals at certain intervals after release of the arterial ligature. Infusion of this blood into sub-lethally hemorrhaged rabbits caused the death of half of the tested animals; a mortality incidence which closely matched the per cent mortality in rabbits shocked by SMA occlusion alone. Blood from sham-operated donor animals did not prove lethal when infused into hemorrhage-prepared rabbits. Infusion of SMAO shock plasma did not result in the death of recipient animals, even though the whole blood source of the plasma had proven to be lethal upon infusion into hemorrhage-prepared rabbits. Moreover, following pretreatment of donor animals with a non-absorbable antibiotic per os, the number of actively reproducing bacteria in the intestinal fluids was reduced to less than 0.1 per cent of normal; nevertheless, the incidence of passive transfer of lethality from shocked donors receiving this pretreatment was not consistently reduced. Furthermore, when SMAO shock portal blood was tested for the presence of bacterial endotoxin by the sensitive dermal epinephrine reaction, although some blood samples demonstrated lesion-provoking activity, there was no correlation between this activity and the lethal properties of the blood samples. In seeking an explanation for the production of dermal epinephrine lesions by non-lethal shock blood, a positive correlation was demonstrated between the lesion-provoking activity of portal blood and the serotonin content of intestinal tissues of rabbits shocked by SMA ligation. In addition, small amounts of serotonin were shown to be capable of provoking dermal epinephrine reactions in rabbits, under the same conditions used to test the lesion-provoking activity of portal blood. It was therefore concluded that: (a) a toxic factor(s) is present in the portal blood of SMAO-shocked rabbits; (b) that this factor(s) is not likely to be a bacterial endotoxin; and (c) that the occasional provocation of a dermal epinephrine reaction by portal blood from SMAO-shocked rabbits, a property heretofore exclusively attributed to the presence of endotoxin in shock blood, can be entirely explained on the basis of elevated levels of serotonin in this blood.

Animals↗
PubMed1961

Active ion transport across canine blood vessel walls.

Experiments giving evidence of active Na and Cl ion fluxes across large canine blood vessel walls (aorta, vena cava) in vitro have been presented. The information has been obtained using ion tracer techniques after Ussing and with diffusion cells of the Hogben type. The available data suggest that the membranes are satisfactorily oxygenated by the bathing solutions saturated with oxygen at atmospheric pressure. Evidence is offered which indicates that active ion transport does occur across the aorta and vena cava in in vitro experiments. Under the conditions of the experiment net Na and Cl flux takes place from intima to adventitia across the aorta, and from adventitia to intima across the vena cava at low measured potential differences. The possible relationships of derangement of active ion transport mechanisms, produced by electric currents and tissue injury potential differences, to intravascular thrombosis are alluded to. It would appear that sodium and chloride fluxes across large blood vessel walls in vitro occur at least in part as the result of metabolic processes and cannot be explained simply on the basis of diffusion across a semipermeable membrane.

Animals↗