The stages of osmotic haemolysis.

The haemolysis of individual human erythrocytes has been observed using an inverted microscope and cine-camera. 2. With each permeant (glycerol, propylene glycol, ethylene glycol, urea and water) haemolysis is a multistage process. The stages are swelling, popping, reduction in volume possibly accompanied by ion leakage and, finally, haemoglobin leakage. 3. The classical haemolysis time (Th) is made up of a swelling time (Tsw) and a stress time (Tst). Tst is not negligible and with the faster permeants it may occupy more than 75% of the haemolysis time. 4. The stress time can also be divided into two parts: a K+ leak time (TK) during which the cell shrinks and a time (THb) during which haemoglobin is leaving the cell. THb occupies a substantial part of Th, from 25 to 65%, and is relatively longer in fast haemolysis. 5. There is a wide spread in the permeability coefficient to glycerol in a population of erythrocytes. The distribution is compatible with a Gaussian distribution. The mean permeability is 1-79 X 10(-6) cm/sec and the S.D. is +/0 0-45 X 10(-6) cm/sec. 6. The correlation between haemolysis time and swelling time for individual erythrocytes is poor, especially for fast haemolysis. Consequently, a measure of the distribution of haemolysis time does not give a related distribution of the swelling time or of the calculated permeability for individual erythrocytes.