9306555 Benyajati The goal of this proposal is to elucidate the mechanisms and regulation of the transport of taurine in vertebrate kidneys. Taurine is an abundant amino acid which functions as an intracellular osmolyte, important in the regulation of cell volume. The snake kidney can simultaneously reabsorb and secrete taurine and membrane and membrane vesicle preparations have been used to study the transport mechanisms in this species. The experiments in this proposal will test the hypothesis that secretion of taurine across the kidney cells occurs under conditions of low osmolality, low NaCl/and or high K+concentration in the extracellular fluid. These studies will be done in intact animals, isolated units of the kidney (nephrons) and isolated membranes. Conditions of renal transport in vivo will be correlated with the specific transport characteristics at the membrane level in vitro. These studies will provide new information on the mechanisms by which taurine preforms its functions, and will also aid in understanding osmoregulation at the cellular and organismic levels. ***
