Platelet adhesion and arteriolar dilation in the photothrombosis: observation with the rat closed cranial and spinal windows

Ishikawa, Mami; Sekizuka, Eiichi; Oshio, Chikara; Sato, Shuzo; Yamaguchi, Noriyuki; Terao, Satoshi; Tsukada, Kosuke; Minamitani, Haruyuki; Kawase, Takeshi

« Previous Next »Journal of the Neurological Sciences
Volume 194, Issue 1 , Pages 59-69, 15 February 2002

Platelet adhesion and arteriolar dilation in the photothrombosis: observation with the rat closed cranial and spinal windows

Mami Ishikawa
- Corresponding author. Department of Molecular and Cellular Physiology, LSU Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA. Tel.: +1-318-675-6011; fax: +1-318-675-6005
- Clinical Research Unit, National Saitama Hospital, 2-1 Suwa, Wako-city, Saitama 351-0102, Japan
- Department of Neurosurgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
Eiichi Sekizuka
- Clinical Research Unit, National Saitama Hospital, 2-1 Suwa, Wako-city, Saitama 351-0102, Japan
Chikara Oshio
- Clinical Research Unit, National Saitama Hospital, 2-1 Suwa, Wako-city, Saitama 351-0102, Japan
Shuzo Sato
- Department of Neurosurgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
Noriyuki Yamaguchi
- Department of Neurosurgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
Satoshi Terao
- Clinical Research Unit, National Saitama Hospital, 2-1 Suwa, Wako-city, Saitama 351-0102, Japan
Kosuke Tsukada
- Faculty of Science and Technology, Institute of Biomedical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama-city, Kanagawa 223-8522, Japan
Haruyuki Minamitani
- Faculty of Science and Technology, Institute of Biomedical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama-city, Kanagawa 223-8522, Japan
Takeshi Kawase
- Department of Neurosurgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan

Received 26 July 2001; received in revised form 19 October 2001; accepted 19 November 2001.

Abstract

The mechanism of cerebral infarction, in which thrombus formation and platelet–endothelium interaction play an important part, have not yet been clearly elucidated in vivo. The aim of this study was to observe rolling and adherent platelets and to analyze adherent leukocytes and vessel diameter change in vivo using a photothrombotic vessel occlusion model.

A photothrombosis, which is mediated by free radicals, was induced in male Wistar rats in the presence of a photosensitizing dye (Photofrin II) and exposure to a filtered light. Rhodamine 6G-labeled platelets and leukocytes were visualized with intravital fluorescence videomicroscopy through a closed cranial or spinal window. The vessel diameter, photothrombosis and leukocyte adhesion were analyzed.

Rolling and adherent platelets were observed during irradiation through the cerebral and spinal window. Before the platelets were recognized, the irradiated arteriole dilated significantly. After the photochemical occlusion of an arteriole, other arterioles also dilated and the adherent leukocytes increased in the venules. The photothrombi were almost completely composed of platelets according to electron microscopic analysis. The arteriolar dilation rate and the number of adherent leukocytes in the cerebrum were greater than those in the spinal cord.

By combining the photochemical thrombus formation and the fluorescence microscope techniques, we were able for the first time to observe rolling and adherent platelets and microvascular responses during photothrombosis in the cerebral and spinal microvasculature. It is suggested that free radicals, which can lead to platelet aggregation, play an important role as a cerebral vasodilator. This model is useful for cerebral and spinal microcirculatory analysis to investigate the platelet–endothelium interaction, the platelet aggregation and the effect of free radicals on cerebral and spinal microcirculation.

Keywords: Photothrombus, Activated oxygens, Fluorescence microscope, Platelet, Leukocyte, Adhesion