Studies of blood flow through the spinal cord of rabbit using the H2 clearance method

: Using the H2 clearance method, spinal cord blood flow of the rabbit could be steadily measured. This allowed examination of blood flow problems using data analysis to provide informed decisions as to whether or not the blood flow through the gray and white matter was distinguishable. Spinal cord blood flow was also compared through the cervical, thoracic, and lumbar cord regions. The results were as follows: 1. The H2 clearance curves consisted of about 70% monoexponential curve (Mono), and 30% biexponenial curve (Bi), with a tendency toward higher values in the latter. 2. In Bi, a significant positive correlation was noted between the total flow values and the initial slope method values. The initial slope method was therefore used for subsequent data analysis. 3. By using a histogram to evaluate the data on each medullary segment, it was possible to separate a subgroup with a peak around 20 ml/100 g/min and another one with a peak around 40 ml/100 g/min. Based on the microangiographic findings, a more abundant vascular distribution was demonstrated in the gray matter than in the white matter. The first subgroup was noted corresponding to the blood flow through the white matter, and the latter through the gray matter. When the blood flow through the white and gray matter was calculated according to the subgroup data base, the flow ratio through the white and gray matter was 1:2. 4. Comparing the blood flow through each spinal cord segment revealed no significant difference at a p level of 0.01.