Hypoxia inhibits the regulatory volume decrease in red blood cells of common frog (Rana temporaria)

Red blood cells of vertebrates can restore their cellular volume after hyposmotic swelling. The process strictly depends on oxygen availability in the environment. However, the role of hemoglobin in regulation of cell volume recovery is not clear yet. Little is known about the osmotic reactions and regulatory volume decrease of amphibian red blood cells. We investigated volume recovery process in oxygenated (oxyhemoglobin concentration 97 ± 3% of total hemoglobin) deoxygenated (96 ± 2% of deoxyhemolobin) and oxidized (47 ± 2% of methemoglobin, 41 ± 3% of deoxyhemoglobin) red blood cells of common frog (Rana temporaria) after hyposmotic swelling. Using the low-angle light scattering method we demonstrated the regulatory volume decrease in oxygenated cells and showed that the process was eliminated in hypoxic conditions. Reoxygenation of hypoxic cells restored the regulatory volume decrease. Oxidation of cellular hemoglobin to methemoglobin inhibited the volume recovery response in hyposmotically swollen oxygenated and reoxygenated hypoxic cells.