title: Effects of acute exposure to hyperbaric oxygen on the rheology and morphology of the red blood cells in the rat.
abstract: The effects of acute exposure to hyperbaric oxygen (HBO) on the rheology and morphology of red blood cells (RBC) were studied in three groups of Sprague-Dawley rats: a control (CON) group comprised rats not exposed to HBO, a second group was exposed to HBO at 2.8 atm for 6 hr and studied immediately after the exposure (HBO), and a third group was examined after being allowed to recover in room air for 24 hr after exposure to HBO (REC). RBC deformability was assessed by two different techniques, the ektacytometer and the micropore filters. While the ektacytometer did not detect a significant difference among the three groups, the filtration method showed that acute exposure to HBO causes a significant increase in the filtration index (FI), denoting a significant reduction in RBC deformability. However, this reduction returned to the control level after 24 hr of recovery in air (FI, 7.1 +/- 1.2 in CON and 9.5 +/- 2.6 in REC compared to 36.2 +/- 3.7 in HBO, P < 0.0001). The morphology of RBC was studied by scanning electron microscopy. Immediately after exposure to HBO there was a marked increase in the echinocytes (41.6 +/- 5.9%) compared to a control level of 16.7 +/- 4.8%, P < 0.05. The increase in the echinocytes became less pronounced after 24 hr of recovery (23.5 +/- 9.3%). In conclusion, acute exposure to HBO causes significant alterations in RBC rheology and morphology. Due to the sensitivity of the micropore filters, we hypothesize that the decrease in RBC deformability might affect their flow through small-caliber blood vessels. These alterations, however, are reversible after a relatively short period of recovery in air.
authors.affiliation: Department of Anesthesiology, State University of New York, Health Science Center at Syracuse 13210, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Amin
authors.forename: W S
authors.initials: WS
authors.lastname: Kaniewski
authors.forename: D
authors.initials: D
authors.lastname: Cohen
authors.forename: E M
authors.initials: EM
authors.lastname: Camporesi
authors.forename: T S
authors.initials: TS
authors.lastname: Hakim
mesh_terms: D000818:Animals; D048429:Cell Size; D004912:Erythrocytes / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D006931:Hyperbaric Oxygenation; D008297:Male; D008855:Microscopy, Electron, Scanning; D051381:Rats; D017207:Rats, Sprague-Dawley; D012212:Rheology