Role of SIRT3 in Compensatory Flow-Induced Dilation Following High Pressure Stress in the Human Microcirculation

Abstract

Reductions in flow-induced dilation (FID; vasodilation in response to increased blood flow from shear stress) is predictive of future adverse cardiac events. Vasodilatory capacity to flow is maintained in arterioles from healthy adults following exposure to high intraluminal pressure (150mmHg, 30min) by utilizing hydrogen peroxide (H2O2) to compensate for decreased bioavailability of nitric oxide (NO). Here, we tested the hypothesis that knockdown of NAD-dependent deacetylase sirtuin-3 (SIRT3), a mitochondrial protein activated during stress and known to stimulate cellular survival pathways, would prevent compensatory signaling during FID and reduce overall vasodilatory capacity following high intraluminal pressure. Adipose arterioles (100-200μm) from otherwise healthy adults (0-1 risk factor for cardiovascular disease) were treated intraluminally with siSIRT3 or negative control siRNA for 16-20hrs and cannulated for videomicroscopy prior to pre-constriction with endothelin-1. Changes in internal microvessel diameter in response to graded increases in flow were measured. Maximal dilation to flow was maintained both pre- and post-pressure in arterioles treated with negative control siRNA (93.3%±2.3 of maximal dilator capacity±SEM, n=3 versus 69.9%±11.5, n=3, respectively), however, vasodilatory capacity was significantly reduced post-pressure in arterioles treated with siSIRT3 (19.8%±5.7, n=3) compared to pre-pressure (76.0%±10.6, n=3, p<0.01, one-way ANOVA). These data suggest that SIRT3 plays a key mechanistic component in compensatory signaling during flow in human arterioles following stress. We conclude that SIRT3 may be a potential therapeutic target to increase vascular resilience and protect from stress in the human microcirculation thereby preventing microvascular dysfunction and future cardiovascular disease. None. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.