Abstract Details

Title Cerebral Autoregulation: The Genetic Basis of The Myogenic Response

Topic Cerebrovascular Disease and Interventional Neurology

Presentation(s) P04 - (-)

Poster/Presentation
Number 046

Objective

Background BACKGROUND: Cerebral blood flow (CBF) autoregulation (AR) is a homeostatic mechanism that maintains constant oxygen delivery to the brain despite fluctuations in cerebral perfusion pressure. Myogenic response is vital in maintaining AR, and it is impaired following stroke and traumatic brain injury and shifted to higher pressures in hypertension. The Fawn Hooded Hypertensive (FHH) rat, a genetic model of hypertension that is very susceptible to renal end organ damage, exhibits impaired myogenic response in afferent arterioles.

Design/Methods DESIGN/METHODS: Rats that include (autoregulation (AR) +) and exclude (AR-) the 2.4Mbp region were bred transferring this region from Brown Norway (BN) RNO1 into the FHH rat genetic background. Laser Doppler flowmetry to study CBF autoregulation, vascular reactivity to measure myogenic response and transient- Middle Cerebral Artery Occlusion studies to assess CBF perfusion were performed.

Results RESULTS: AR of CBF was poor in FHH and FHH.1BN AR- strains, but it was completely restored in AR+ strains. MCA diameters of FHH rats increased from 140 + 14 to 157+18[mu]m but decreased in FHH.1BN AR+ congenic strains from 137+ 5 to 94+ 7[mu]m when transmural pressure was increased from 40 to 140mmHg. Transient occlusion of MCA reduced CBF by 80% in all strains. However, the hyperemic response following ischemia was significantly greater in FHH and AR- strains than that seen in AR+ rats (AR-: 173 ± 11% versus AR+: 124 ± 5%).

Conclusions CONCLUSIONS: These results indicate that there is a gene that plays a critical role in regulation of the myogenic tone in the 2.4Mbp region of RNO1. Transfer of this region from BN to FHH rats restores AR of CBF, vascular reactivity and reduces cerebral injury.

Authors/Disclosures
Hurtis Tullos PRESENTER	No disclosure on file
	No disclosure on file
	No disclosure on file
Syed A. Raza, MD (National Institutes of Health)	Dr. Raza has nothing to disclose.
	No disclosure on file
	No disclosure on file
	No disclosure on file

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