Guanidinoethyl sulfonate, also known as taurocyamine, is a natural guanidine-taurine analog derived from taurine. It is an intermediate of taurine and hypotaurine metabolism and is phosphorylated by taurocyamine kinase. Guanidinoethyl sulfonate competitively inhibits taurine uptake by sodium-dependent taurine transporters in rat hepatocytes (Ki = 1.75 mM). It also acts as a competitive glycine receptor antagonist in mouse striatal neurons. Plasma levels of guanidinoethyl sulfonate are significantly increased in patients with chronic renal failure.
