Importance of the malate-aspartate shuttle for the reoxidation of glycolytically produced NADH and for cell aggregation in porcine blood platelets.

Malate dehydrogenase (EC 1.1.1.37) and aspartate aminotransferase (EC 2.6.1.1) are present in porcine blood platelets in both mitochondria and the cytosol. The latter enzyme is inhibited in a typical way by aminooxycompounds and cycloserine. Blocking of aminotransferase or inhibition of the mitochondrial dicarboxylate carrier by butylmalonate stimulates lactate production by intact platelets and inhibits their aggregation induced by ADP or collagen. These results indicate that the reoxidation of cytosolic NADH via the malate-aspartate shuttle is important for covering the energy demand of platelets necessary for their stimulation.