Intracarotid artery cold saline infusion (ICSI) is an effective method for protecting brain tissue, but its use is limited because of undesirable secondary effects, such as severe decreases in hematocrit levels, as well as its relatively brief duration. In this study, the authors describe and investigate the effects of a novel ICSI pattern (interrupted ICSI) relative to the traditional method (uninterrupted ICSI).
Ischemic strokes were induced in 85 male Sprague-Dawley rats by occluding the middle cerebral artery for 3 hours using an intraluminal filament. Uninterrupted infusion groups received an infusion at 15 ml/hour for 30 minutes continuously. The same infusion speed was used in the interrupted infusion groups, but the whole duration was divided into trisections, and there was a 20-minute interval without infusion between sections. Forty-eight hours after reperfusion, H & E and silver nitrate staining were utilized for morphological assessment. Infarct sizes and brain water contents were determined using H & E staining and the dry-wet weight method, respectively. Levels of neuron-specific enolase (NSE), S100β protein, and matrix metalloproteinase 9 (MMP-9) in the serum were determined using enzyme-linked immunosorbent assay. Neurological deficits were also evaluated.
Histology showed that interrupted ICSI did not affect neurons or fibers in rat brains, which suggests that this method is safe for brain tissues with ischemia. The duration of hypothermia induced by interrupted ICSI was longer than that induced via the traditional method, and the decrease in hematocrit levels was less pronounced. There were no differences in infarct size or brain water content between uninterrupted and interrupted ICSI groups, but neuron-specific enolase and matrix metalloproteinase 9 serum levels were more reduced after interrupted ICSI than after the traditional method.
Interrupted ICSI is a safe method. Compared with traditional ICSI, the interrupted method has a longer duration of hypothermia and less effect on hematocrit and offers more potentially improved neuroprotection, thereby making it more attractive as an infusion technique in the clinic.