Pyruvate dehydrogenase is the entry point for the glycolytic product pyruvate into oxidative metabolism (the citric acid cycle and oxidative phosphorylation). Because it occupies such an important checkpoint in metabolism, it is tightly regulated. Determine whether the given conditions promote entry into oxidative metabolism or limit entry into oxidative metabolism. These abbreviations may be used: PDH is pyruvate dehydrogenase; PDK is pyruvate dehydrogenase kinase; PDP is pyruvate dehydrogenase phosphatase.