Definition: Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.
Input: Abstract: In male Wistar rats, renal adenosine triphosphate (ATP), inorganic phosphate (Pi) and intracellular pH were measured by 31phosphorus nuclear magnetic resonance (31P NMR) and correlated with renal function before, during, and for one hour after a period of 30 to 40 minutes hemorrhagic hypotension. In animals which suffered no change in these metabolites during hypotension, retransfusion immediately restored normal renal function. When metabolite changes were observed during hypotension, they occurred suddenly with severe ATP depletion, Pi accumulation, and intracellular acidosis occurring almost concurrently. Metabolic changes of this magnitude were always associated with renal dysfunction in the post-hypotensive period, which occurred even when the period of biochemical change was only 10 to 15 minutes. The abnormalities in post-hypotensive renal function resemble the pattern of change seen in human acute tubular necrosis (ATN): depressed glomerular filtration rate (GFR), urine output varying from polyuria to oliguria, decreased urine to plasma inulin ratio, increased urinary sodium concentration, increased fractional excretion of sodium, and increased fractional excretion of potassium. It is postulated that changes in renal cellular energy status during hemorrhagic hypotension distinguish pre-renal failure from early or incipient ATN.

Acute renal failure in hemorrhagic hypotension: cellular energetics and renal function.