Visualization of rat pial microcirculation using the novel orthogonal polarized spectral (OPS) imaging after brain injury

Recently, the novel optical system, orthogonal polarized spectral (OPS) ima ging was developed to visualize microcirculation. Investigation of changes in microcirculation is essential for physiological, pathophysiological, and pharmacological studies. In the present study applicability of OPS imaging was assessed to study,pial microcirculation in normal and traumatized rat brain. High quality images of rat pial microcirculation in normal and traum atized rats were generated with the OPS imaging, allowing to easily differe ntiate arterioles and venules with the dura remaining intact. In non-trauma tized rats, mean vessel diameter of arterioles and venules of five differen t cortical regions was 19.1 +/- 2.7 and 22.2 +/- 1.4 gm, respectively. In t he early phase following focal cortical contusion vessel diameter was signi ficantly decreased in arterioles by 28% while diameter in venules was signi ficantly increased by 27%. For technical reasons velocity in arterioles was not measurable. In venules, mean flow velocity of 0.68 +/- 0.08 mm/s was s ignificantly decreased by 50% at 30 min after trauma. OPS imaging is an eas y to use optical system allowing to generate high quality images and to rel iably investigate pial microcirculation without having to remove the dura. This technique opens the possibility to perform longitudinal studies invest igating changes in pial microcirculation. (C) 2001 Elsevier Science B.V. Al l rights reserved.