title: Hydroxyethyl starch: the effect of molecular weight and degree of substitution on intravascular retention in vivo.
abstract: BACKGROUND
  Hydroxyethyl starch (HES) solution is characterized by its mean molecular weight (MW), concentration, and degree of substitution (DS). This character varies worldwide.
  
  
  METHODS
  After binding fluorescein-isothiocyanate (FITC-HES), we evaluated the retention rate of three types of 6% HES in the A2 and V2 blood vessels of rat cremaster muscles using intravital microscopy in a mild hemorrhage model (10% of total blood volume). After blood withdrawal, we infused three types of FITC-HES: HES-A (MW 150-200 kDa, DS 0.6-0.68), HES-B (MW 175-225 kDa, DS 0.45-0.55), or HES-C (MW 550-850 kDa, DS 0.7-0.8) before determining the FITC-HES retention rate in the intravital microscope.
  
  
  RESULTS
  For V2, the FITC-HES retention rates 120 min after the start of the infusion were 27% +/- 7.2% of baseline values (HES-A), 65% +/- 9.1% (HES-B), and 86% +/- 9.6% (HES-C); for A2 they were 27% +/- 6.6%, 73% +/- 10.2%, and 89% +/- 8.7%, respectively. HES-B and HES-C were retained in the vessels longer than HES-A (P = 0.028 for V2, P = 0.038 for A2 between HES-B and HES-A; P = 0.022 for V2, P = 0.037 for A2 between HES-C and HES-A). There was no difference in the rate of disappearance from the vessels between HES-B and HES-C.
  
  
  CONCLUSIONS
  HES-B and HES-C are equally retained in the blood vessels. Middle-sized HES-B with low DS and middle substitution pattern stayed in the blood vessels as long as the large-sized HES. HES solutions of varying characters should be examined to optimize HES infusion.
authors: Department of Anesthesiology, Nihon University Graduate School of Dentistry, Tokyo, Japan.
authors: Takashi
authors: T
authors: Hitosugi
authors: Toshiyuki
authors: T
authors: Saito
authors: Sono
authors: S
authors: Suzuki
authors: Ieko
authors: I
authors: Kubota
authors: Emi
authors: E
authors: Shoda
authors: Toru
authors: T
authors: Shimizu
authors: Yoshiyuki
authors: Y
authors: Oi
mesh_terms: D000818:Animals; D001160:Arterioles / Q000378:metabolism; D002199:Capillary Permeability; D004195:Disease Models, Animal; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D006470:Hemorrhage / Q000378:metabolism* / Q000503:physiopathology; D006895:Hydroxyethyl Starch Derivatives / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D008297:Male; D018715:Microscopy, Video; D015394:Molecular Structure; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000098:blood supply*; D010952:Plasma Substitutes / Q000737:chemistry / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D014699:Venules / Q000378:metabolism
chemical_list: D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes; C050176:fluorescein isothiocyanate-hydroxyethyl starch; D016650:Fluorescein-5-isothiocyanate