Article Figures & Data
Figures
- fig 1.
A, Schematic representation of the experimental set-up. DAT indicates digital audiotape; LAN, local area network; SR, synchrotron radiation.
B, An example of the method used to measure vessel diameters. Radiographic image shows cerebral vessels and a reference copper wire with a diameter of 130 μm (arrowhead). The mean density profiles (thin lines) and the running averaged mean density profiles (thick lines) for the two measured vessels (a and b) and the two sites of the reference wire (c and d) are shown. The diameter is calculated on the basis of the distance between the edges, which are defined as the two half-maximum points of the profile (see Methods). Ordinate represents density; abscissa, distance (μm). The measured value of the reference wire is approximately 130 μm. This angiogram was made from figure 2.
- fig 2.
Cerebral angiogram obtained at baseline. The contrast material was injected into the brachiocephalic artery. Arrows indicate small branches of the circle of Willis; arrowheads, reference copper wires with a diameter of 130 μm. See figure 4A for the names of the vessels. The field of view was 20 × 20 mm
- fig 3.
Vessel diameters, with and without brachiocephalic occlusion, were measured on brachiocephalic angiograms without occlusion (three images in three dogs) and vertebral angiograms with partial brachiocephalic occlusion (nine images in three dogs). The numbers of measured vessels on both sides are indicated in parentheses. The brachiocephalic angiogram of one representative dog is shown in figure 2. MCA indicates middle cerebral artery; PCA, posterior cerebral artery; ACA, anterior cerebellar artery; BA, basilar artery; CoA-1, communicating artery between MCA and PCA; CoA-2, CoA between ACA and BA; PA-1 and PA-2 are the anterior and posterior vessels of the two small branches of the circle of Willis, respectively. Data are means ± SD. *P = .053, **P < .001 (unpaired t-test)
- fig 4.
Temporal digital subtracted image of a cerebral angiogram obtained during CO2 inhalation. The digital image obtained immediately before injection of contrast material into the brachiocephalic artery was subtracted from that obtained during the injection. The field of view was 20 × 20 mm.
A, Before CO2 inhalation. The original image is the same as that shown in figure 2. Arrowheads indicate large branches of the circle of Willis, namely, the middle cerebral artery, the posterior cerebral artery, the anterior cerebellar artery, and the basilar artery; arrows, small branches of the circle of Willis; double arrowheads, the internal carotid artery; double arrows, anastomotic ramus (between the internal carotid artery and the external ophthalmic artery). The anterior cerebellar artery arises from the communicating artery in the dog. PaCO2 was 34.9 mm Hg.
B, During CO2 inhalation, PaCO2 was 125.5 mm Hg.
C, 60 minutes after the completion of CO2 inhalation, PaCO2 was 30.2 mm Hg.
- fig 5.
Effects of CO2 inhalation on changes in vessel diameters in the brains. Vessel diameters were measured on brachiocephalic angiograms before CO2 inhalation, during CO2 inhalation (2 L/min), and 60 minutes after completion of CO2 inhalation in three dogs. The numbers of vessels examined on both sides are indicated in parentheses. Images from one representative dog are shown in figure 4. In one dog, the basilar artery was outside the field of view. Abbreviations are the same as in figure 3. Data are means ± SD. *P < .05 (ANOVA)
Tables
Blood gases and hemodynamic data during CO2 inhalation in three dogs
