title: Physiological responses, organ distribution, and circulation kinetics in anesthetized rats after hypovolemic exchange transfusion with technetium-99m-labeled liposome-encapsulated hemoglobin.
abstract: Physiological responses and circulation properties of liposome-encapsulated hemoglobin (LEH) labeled with technetium-99m (99mTc) were measured in rats after a 10% (170 mg/kg hemoglobin; 430 mg/kg phospholipid) or a 50% (450 mg/kg hemoglobin, 2.3 g/kg phospholipid) hypovolemic exchange transfusion (n = 5 per exchange group). Mean arterial pressure returned to baseline values (105 +/- 8 mmHg) by 90 min post-infusion for both groups. By 20 h, mean arterial pressure remained at baseline values for the 10% group, but dropped to 30 +/- 14 mmHg for the 50% group. For both groups, bradycardia was seen after the exchange period, but heart rate recovered by 30 min for the 10% group and by 90 min for the 50% group. The 99mTc-LEH remained in circulation longer for the 50% group (18.2 h half-life) than for the 10% group (2.4 h half-life). Removal of 99mTc-LEH from the bloodstream was via the liver and spleen. At 20 h, 99mTc-LEH accumulation in these organs was greater for the 10% group (liver, 36.2 +/- 1.7%; spleen, 37.5 +/- 2.5%) than for the 50% group (liver, 17.0 +/- 1.4%; spleen, 17.1 +/- 1.4%). The data show that there is less clearance of 99mTc-LEH from the bloodstream by the reticuloendothelial system after a 50% hypovolemic exchange transfusion, thus supporting the possible use of LEH as an oxygen-carrying resuscitative fluid in situations of severe blood loss.
mesh_terms: D000777:Anesthetics; D000818:Animals; D001775:Blood Circulation / Q000502:physiology*; D001802:Blood Substitutes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004337:Drug Carriers; D005078:Exchange Transfusion, Whole Blood; D006439:Hemodynamics / Q000187:drug effects; D006454:Hemoglobins / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008081:Liposomes; D008297:Male; D008657:Metabolic Clearance Rate; D012157:Mononuclear Phagocyte System / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012769:Shock / Q000628:therapy*; D017556:Technetium Compounds; D014018:Tissue Distribution / Q000502:physiology
chemical_list: D000777:Anesthetics; D001802:Blood Substitutes; D004337:Drug Carriers; D006454:Hemoglobins; D008081:Liposomes; D017556:Technetium Compounds