The Effects of Hypertension on Collateral Arteries (2011)

Undergraduates: Matt Waters, Scott Moore

Faculty Advisor: Jim Faber
Department: Biology

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Collateral arteries are unique arterial anastomoses which provide a supplemental circulation that can prevent or reduce ischemic tissue damage in the presence of an arterial occlusion by remodeling (increasing in diameter). Certain cardiovascular risk factors and disease (CVRFD) have been associated with vascular damage and poorer outcomes from ischemic injury, such as myocardial infarction or stroke. Hypertension (HTN) is a CVRFD with harmful effects on the vasculature. Chronic high blood pressure has been shown to promote vessel loss and narrowing of diameter in normal arteries, through enhothelial dysfunction (decreased eNOS activity and NO bioavailability). Information regarding HTN’s effects on collaterals is less clear. To determine whether HTN causes rarefaction of the native collaterals our lab examined the native cerebral collateral number and diameter of two different mouse models for HTN, PPAR?L/-/ApoE-/- (mild hypertension and dyslipidemia); and RenTgMK+/- (moderate-severe hypertension), which we compared to normatensive control mice. Both sets of mice showed a drop in collateral density (number and diameter), with the more severe model of HTN showing a greater drop in collateral diameter. These data demonstrate that HTN has damaging effects on the native collateral circulation. The loss of native collaterals results in fewer available to remodel, which in an already hypertensive body will result in worse ischemic tissue injury after an acute obstruction.