EFFECTS OF ACUTE EXPOSURE TO HYPERBARIC-OXYGEN ON THE RHEOLOGY AND MORPHOLOGY OF THE RED-BLOOD-CELLS IN THE RAT

The effects of acute exposure to hyperbaric oxygen (HBO) on the theolo gy and morphology of red blood cells (RBC) were studied in three group s of Sprague-Dawley rats: a control (CON) group comprised rats not exp osed to HBO, a second group was exposed to HBO at 2.8 arm for 6 hr and studied immediately after the exposure (HBO), and a third group was e xamined after being allowed to recover in room air for 24 hr after exp osure to HBO (REC). RBC deformability was assessed by two different te chniques, the ektacytometer and the micropore filters. While the ektac ytometer did not detect a significant difference among the three group s, the filtration method showed that acute exposure to HBO causes a si gnificant increase in the filtration index (FI), denoting a significan t 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 C ON 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. I mmediately after exposure to HBO there was a marked increase in the ec hinocytes (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 aft er 24 hr of recovery (23.5 +/- 9.3%). In conclusion, acute exposure to HBO causes significant alterations in RBC rheology and morphology. Du e to the sensitivity of the micropore fillers, we hypothesize that the decrease in RBC deformability might affect their flow through small-c aliber blood vessels. These alterations, however, are reversible after a relatively short period of recovery in air. (C) 1995 Academic Press , Inc.