Abstract P547: Soluble Fiber Diet Alters Cardiovascular Responses To Stress In Normotensive Wky Rats

Abstract

Gut microbiota is crucial for function of the gastrointestinal (GI) tract, and modulates the communication between the GI tract and the central nervous system. Microbial metabolites such as propionate have been shown to regulate blood pressure (BP), while butyrate, one of the major bacterial fermented byproducts, reportedly produces beneficial effects in multiple dysbiosis-related diseases. We previously showed that chronic supplementation with soluble fiber-rich, butyrolytic diet modified microbiota and increased BP in the spontaneously hypertensive rat (SHR). Here, we tested the impact of same diet on BP regulation in the Wistar Kyoto rats (WKY). Methods: Male 4 weeks old WKY were placed on either the fructooligosaccharides/inulin-rich diet (fiber, N=6), or its calorie-matched control diet (control, N=6) (Research Diets, Inc.) for 14 weeks. Baseline BP was measured by tail cuff every week for the duration of the study, and by telemetry at the end of the study and during 20 minutes of restraint stress. Spectral analysis of BP waveform was performed during restraint stress to measure autonomic variables. Results: We observed no significant difference in mean BP measured by tailcuff or by telemetry between the two groups. However, there was an increase in mean BP after 2 minutes of restraint (104.5 ± 7.45 mmHg vs. 116.3 ± 3.19 mmHg; p=0.0411, n=6), which was associated with a trend in increase in LF/HF variable linked with vasovagal balance (1.99 ± 1.43 vs. 3.04 ± 1.46, p=0.17) in the fiber group when submitted to restraint stress. Conclusion: Unlike in the SHR, fiber-rich diet did not alter baseline BP in the normotensive WKY. However, chronic fiber diet produced autonomic imbalance and increased BP in response to restraint stress in the WKY.