Sex-Specific and Dose-Dependent Effects of Drag-Reducing Polymers on Microcirculation and Tissue Oxygenation in Rats After Traumatic Brain Injury

• Published in: Advances in experimental medicine and biology Vol. 1438; p. 77
• Main Authors: Bragin, Denis E, Bragina, Olga A, Kameneva, Marina V, Trofimov, Alex O, Nemoto, Edwin M
• Format: Journal Article
• Language: English
• Published: United States 2023
• Subjects: Animals; Blood-Brain Barrier - metabolism; Brain Injuries, Traumatic - drug therapy; Cerebrovascular Circulation; Female; Male; Microcirculation; Oxygen - metabolism; Polymers - metabolism; Rats; Microcirculation; Traumatic brain injury; Cerebral blood flow; Drag-reducing polymers; NADH autofluorescence; Intracranial pressure; Microvascular flow; Tissue oxygenation
• ISSN: 0065-2598
• DOI: 10.1007/978-3-031-42003-0_13

Traumatic brain injury (TBI) ultimately leads to a reduction in the cerebral metabolic rate for oxygen due to ischemia. Previously, we showed that 2 ppm i.v. of drag-reducing polymers (DRP) improve hemodynamic and oxygen delivery to tissue in a rat model of mild-to-moderate TBI. Here we evaluated sex-specific and dose-dependent effects of DRP on microvascular CBF (mvCBF) and tissue oxygenation in rats after moderate TBI. In vivo two-photon laser scanning microscopy over the rat parietal cortex was used to monitor the effects of DRP on microvascular perfusion, tissue oxygenation, and blood-brain barrier (BBB) permeability. Lateral fluid-percussion TBI (1.5 ATA, 100 ms) was induced after baseline imaging and followed by 4 h of monitoring. DRP was injected at 1, 2, or 4 ppm within 30 min after TBI. Differences between groups were determined using a two-way ANOVA analysis for multiple comparisons and post hoc testing using the Mann-Whitney U test. Moderate TBI progressively decreased mvCBF, leading to tissue hypoxia and BBB degradation in the pericontusion zone (p < 0.05). The i.v. injection of DRP increased near-wall flow velocity and flow rate in arterioles, leading to an increase in the number of erythrocytes entering capillaries, enhancing capillary perfusion and tissue oxygenation while protecting BBB in a dose-dependent manner without significant difference between males and females (p < 0.01). TBI resulted in an increase in intracranial pressure (20.1 ± 3.2 mmHg, p < 0.05), microcirculatory redistribution to non-nutritive microvascular shunt flow, and stagnation of capillary flow, all of which were dose-dependently mitigated by DRP. DRP at 4 ppm was most effective, with a non-significant trend to better outcomes in female rats.