Answer:
Hypertonic blood draws water out of the interstitial fluid, which makes the interstitial fluid hypertonic. This, in turn, draws water out of the cells.
Basically an hype tonic blood has high solute potential,( low water potential) compare with the surrounding plasma and the interstitial fluid. Thus the interstitial fluid is hypotonic to the blood.
Consequently,water with higher potential moves from the interstitial fluid medium into the blood by osmosis through the capillary endothelial. This raises the water potential of the blood, lowering the solute potential, thus making it hypotonic to the interstitial fluid; which is now hypertonic(lower water potential ,due to loss to the blood by osmosis).
Since the interstitial fluids is now hyper tonic to the surrounding cells, water moves from the hypo tonic surrounding cells through osmosis into the interstitial fluids. The sequence continues until a stable internal environment is achieved,