Robert M. Jr. Bryan

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Direct lateral cortical impact through the intact leptomeninges using a pneumatically driven piston produces increasingly severe pathophysiologic derangements with increasing cortical deformation. We studied the histopathologic correlates of cortical impact injury produced by 2 mm, 2.5 mm, and 3 mm deformation in the rat at 5 m/sec. Additionally, the effect(More)
The cerebrovascular endothelium exerts a profound influence on cerebral vessels and cerebral blood flow. This review summarizes current knowledge of various dilator and constrictor mechanisms intrinsic to the cerebrovascular endothelium. The endothelium contributes to the resting tone of cerebral arteries and arterioles by tonically releasing nitric oxide(More)
Regional cerebral blood flow (rCBF) and laser-Doppler perfusion were measured in rats after controlled cortical impact injury (CCII), a model of traumatic brain injury. Male Long-Evans rats were anesthetized with isoflurane and surgically prepared with arterial and venous cannulae. CCII was induced after a craniectomy by deforming the right parietal cortex(More)
Regional cerebral glucose utilization (rCMRgl) was studied during insulin-induced hypoglycemia in unanesthetized rats. Rats were surgically prepared using halothane and nitrous oxide anesthesia and allowed 5 h to recover from the anesthesia before rCMRgl was measured. The rCMRgl was measured using [6-14C]glucose in a normoglycemic control group and two(More)
Elevations in arterial pressure associated with hypertension, microgravity, and prolonged bed rest alter cerebrovascular autoregulation in humans. Using head-down tail suspension (HDT) in rats to induce cephalic fluid shifts and elevate arterial pressure, this study tested the hypothesis that 2-wk HDT enhances cerebral artery vasoconstriction and that an(More)
BACKGROUND AND PURPOSE Traumatic injury makes the brain susceptible to secondary insults. An uncomplicated mild lateral cortical impact injury (3 m/s, 2.5-mm deformation) that causes little or no permanent sequelae results in a large contusion at the impact site when the traumatic injury is complicated by a secondary insult, such as 40 minutes of bilateral(More)
Cerebrovascular reactivity to CO(2) or hypotension was studied in vivo and in vitro [pressurized arteries ( approximately 82 micrometer) and arterioles ( approximately 30 micrometer)] at 1 h after mild controlled cortical impact (CCI) injury in rats. The cortical perfusion response [assessed using laser-Doppler flowmetry (LDF)] to altered CO(2) was(More)
Previous models of the cerebrovascular smooth muscle cell have not addressed the interaction between the electrical, chemical, and mechanical components of cell function during the development of active tension. These models are primarily electrical, biochemical or mechanical in their orientation, and do not permit a full exploration of how the smooth(More)
Previous data indicate that regional cerebral blood flow (rCBF) decreases during acute and chronic hyperglycemia. To test the hypothesis that the decrease in rCBF is secondary to a decrease in cerebral metabolic rate, the rate of regional cerebral glucose utilization (rCMRgl) was measured in awake-restrained rats during acute and chronic hyperglycemia.(More)
We tested the hypothesis that TREK-1, a two-pore domain K channel, is involved with dilations in arteries. Because there are no selective activators or inhibitors of TREK-1, we generated a mouse line deficient in TREK-1. Endothelium-mediated dilations were not different in arteries from wild-type (WT) and TREK-1 knockout (KO) mice. This includes dilations(More)