Renal blood flow and oxygen consumption
Per gram of base weight, the normal kidneys consume oxygen at twice the rate of the brain but 7 times the flow of the brain.
For a person weighing 70 kilograms, the blood flow through both kidneys is about 1100 ml/min, or about 22% of the blood flowing from the heart. It is estimated that 2 kidneys make up about 0.4% of total body weight, but clearly, they receive extremely high blood volume compared to other organs.
As with other tissues, the bloodstream supplies the kidneys with nourishment and eliminates waste products. However, a large amount of flow through the kidneys exceeds this need. The purpose of this flow is to provide enough plasma for high-speed glomerular filtration and is necessary to regulate body fluid volume and solute concentration. The mechanism of renal blood flow regulation is associated with the regulation of the glomerular filtration rate and the renal excretion function.
Per gram of base weight, the normal kidneys consume oxygen at twice the rate of the brain but 7 times the flow of the brain. As a result, the amount of oxygen reaching the kidneys exceeds the required metabolism, and the dynamic-venous system takes oxygen less than other tissues. The large filtration fraction of renal oxygen consumption is related to the high rate of solute reabsorption in the renal tubules. If renal flow and glomerular filtration rate decreases and less amount of solute is filtered.
Figure. Relationship between oxygen consumption and sodium reabsorption in the kidney. Relationship between renal oxygen consumption with blood supply and glomerular filtration in blood pressure variations.
Less amount of solute is reabsorbed and less oxygen consumption. Hence, the oxygen consumption value focuses on the renal tubular solute reabsorption, in relation to the glomerular filtration rate and the solute filtration rate. If glomerular filtration is completely stopped, solute reabsorption also stops and oxygen consumption decreases to about a fifth of normal. The remaining oxygen-consuming reflex is the primary metabolic essential for kidney cells.