title: Histamine level changes in the plasma and tissues in hemorrhagic shock.
abstract: Histamine (H) levels have been reported during various types of shock, but there is a paucity of such data during hemorrhagic shock. The present study demonstrates a rapid, severalfold increase of radioenzymatically measured plasma H in conscious and anesthetized dogs subjected to experimental hemorrhagic shock. Shock was elicited by bleeding to a mean arterial blood pressure of 5.3 kPa, and maintained until 20% of the maximal bleeding volume (MBV) was taken back by the animal. The corresponding figures in the anesthetized group were 4 kPa and 30% uptake. The increased H level persisted in both groups during hypovolemia and remained above the control value following reinfusion. Survival was examined in the conscious group. At MBV, survivors had significantly higher H levels and H/norepinephrine and H/renin activity ratios in the plasma than nonsurvivors. The H level increased in the liver, lungs, spleen, left atrium and ventricle, and blood vessel walls (superior mesenteric artery, small jejunal arteries and veins, femoral artery and vein). The H/norepinephrine ratio increased in the left ventricle and blood vessel walls. The increase of H in the blood plasma and blood vessels during hemorrhagic shock may exemplify a counterregulation against excessive vasoconstriction and could be a positive factor in survival.
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000032:analysis; D004285:Dogs; D006632:Histamine / Q000032:analysis*; D008099:Liver / Q000032:analysis; D008168:Lung / Q000032:analysis; D009132:Muscles / Q000032:analysis; D009206:Myocardium / Q000032:analysis; D009638:Norepinephrine / Q000032:analysis; D012083:Renin / Q000097:blood; D012771:Shock, Hemorrhagic / Q000378:metabolism*; D013154:Spleen / Q000032:analysis
chemical_list: D006632:Histamine; D012083:Renin; D009638:Norepinephrine