Isosmotic swelling of skate (<i>Raja erinacea</i>) red blood cells causes a volume regulatory release of intracellular taurine

Abstract

Abstract Animal cells swell when placed in a hypotonic medium and then regulate their volume by releasing intracellular solutes. The aim of this study was to determine whether hypoosmolarity or cell swelling is the stimulus that triggers the release of solutes. Swelling skate red blood cells (RBC) by placing them in isosmotic media containing rapidly penetrating solutes (NH 4 Cl, ethylene glycol) caused increased release of taurine from the cells. Isosmotic swelling also increased the cellular levels of radiolabeled diacylglycerol, a second messenger previously implicated in volume regulation by skate RBC. These results indicate that the release of intracellular solutes by hypoosmotically stressed skate RBC is brought about by cell swelling.