[Effect of the blood flow rate in the carotid artery on the hematocrit of the blood distributed to the brain].

The red cell count and hematocrit were determined in the blood distributed to the rabbit brain through the carotid artery. Both parameters were found to be far greater than those in the blood distributed to the hind limb through the femoral artery. The decrease in the blood flow velocity in the carotid artery (caused by local luminal narrowing and increase in the flow resistance) brought about a proportional diminution of both red cells and hematocrit in the blood inflowing to the brain. Meanwhile these parameters remained unchanged in the control arteries (femoral and contralateral carotid ones). Hence the separation of red blood cells from the blood plasma in the vascular system occurs in the arterial branchings and depends on the blood flow velocity in the appropriate branches.