[Taurine transport in the heart].

The rat heart accumulates taurine against the concentration gradient when perfused for 60 minutes with solutions containing taurine in concentrations of 0.01 to 0.5 mM. The uptake of taurine by the myocardium at 37 degrees C is characterized by kinetic constants Km equal to 3.3 micron and Vmax equal to 0.77 micron/min. Heart taurine uptake is inhibited by sodium azide and carbonylcyanide-m-chlorophenylhydrosone and reduced by 30-50% by ouabain. Partial or total replacement of Na+ or K+ by equimolar amounts of trihydrochloride reduces taurine uptake. Competitive inhibition of taurine transport by beta-alanine and GABA is noted. The presence of alpha-alanine in the external medium does not affect the passage of taurine from the perfusate into the myocardium. It is concluded that the uptake of taurine by the rat heart is accomplished by means of active transport through a transport system which possesses affinity to gamma- and beta-amino acids.