Skeletal muscles in the body have a small reserve of ATP. During the first few seconds after contraction, phosphocreatine is used by the enzyme creatine kinase in order to phosphorylate ADP to ATP before the mitochondria start producing it. CK is also found in heart muscle cells, which is why elevated levels of CK in the blood can indicate a heart attack or some other damage to the heart muscle. However, supposing that, for whatever reason, a person's creatine kinase enzymes were to be either inhibited or the supplies of creatine/phosphocreatine were to disappear, what would happen? Could the heart still remain functional without it? What about other muscles and organs?