Elevated blood pressure causes larger hematoma in a rat model of intracerebral hemorrhage.

Hypertension has been recognized as an independent risk factor for intracerebral hemorrhage (ICH). The objective of this study was to assess the effect of chronically elevated blood pressure on amount of hematoma in a rat model of ICH. A total of 46 rats were divided into two groups-normotensive group (n = 18) and spontaneously hypertensive group (n = 28). To induce ICH, we delivered 2 μL of collagenase solution (0.1 U/1 μL normal saline) into the striatum. Each animal's brain was removed 24 h post-surgery for spectrophotometric hemoglobin assay. Equal or unequal variance t tests were performed to assess changes in variables between the hypertensive and normotensive groups. Tissue analysis revealed a statistically significant difference in optical density percent change at 540-nm wavelength for the hypertensive vs. the normotensive group (261.47 ± 103.68 and 133.33 ± 58.53, p < 0.0001, respectively). As compared to the normotensive rats, hypertensive rats exhibited a higher neurological deficit, loss of balance and coordination, and loss of motor function. Our results demonstrated that hypertensive rats had significantly higher amounts of hemorrhage in comparison to normotensive ones. These findings support the need for further adequately powered studies to investigate differences in amount of hematoma and corresponding functional impairments due to ICH among hypertensive vs. normotensive rats.