HTK-N contains protective constituents, such as Nα-acetyl-L-histidine, which improves endothelial function after vascular ischemia/reperfusion[15], L-arginine as a substrate for the endothelial nitric oxide synthase to enhance the blood flow[16], L-alanine and L-glycine to decrease the sodium-influx[17, 18], and α-Ketoglutarate, which improves cardiac function after cardioplegic cardiac arrest[19]. The gene discussed is NOS3; the disease is cardiac arrest.