Final answer:
A decrease in blood supply to the renal tubule results in decreased reabsorption of water and solutes due to impaired ADH activity and less water being reabsorbed in the collecting ducts.
Step-by-step explanation:
The effect of a decrease in the blood supply on the renal tubule is decreased reabsorption of water and solutes. This occurs because there is less blood flow to facilitate the transport of substances from the filtrate back into the bloodstream. With decreased blood flow, essential processes like the activity of anti-diuretic hormone (ADH) that regulates water reabsorption in the kidneys are impaired, leading to less water being reabsorbed in the collecting ducts. Consequently, there is a reduction in the volume of water reabsorbed, which results in increased urine output and a decrease in the blood volume.