Diet-related changes in the control mechanisms for vasomotion in the microcirculation
Authors: Ramnanansingh Timmy , Lewis Aneisha , Youssef Farid , Singh Shamjeet , Gonzalez-Juarbe Norberto , Wiscovitch-Russo Rosana , Carrington Christine , Addae Jonas 
Published: May 2023

Diet affects peripheral blood flow and the control mechanisms for microcirculation. Our objective was to determine the extent to which the five main control mechanisms of cutaneous microcirculation i.e., cardiac, respiratory, myogenic, neurogenic, and metabolic factors are affected by poor diet and prebiotic intake, and the associated changes in gut microbiome. Male Sprague-Dawley rats, 6-8 weeks old, were randomly allocated to four groups (n=7 each): Group 1 – Regular-diet (CON), Group 2 – Cafeteria-diet (CAF), Group 3 - Regular-diet with inulin prebiotic (PRE), and Group 4 – Cafeteria-diet with prebiotic (PRE-CAF). Groups 1 and 3 received standard rat chow with macronutrient content (kcal) of 75.9% carbohydrates, 14.1% protein and 10% fat. Groups 2 and 4 had access to 200 ml of commercial soft drink; they also received standard chow plus a CAF diet consisting of white-bread, canned-sausages, and cookies with macronutrient content (kcal) of 38% carbohydrates, 14% protein and 48% fat. Groups 3 and 4 were given a 10 % (w/w) inulin prebiotic dissolved in the water or drink. Food, water and soft drink were available ad libitum and supplied daily for six months. Faecal samples were collected from rats during experimental weeks 0 to13. The composition of gut microbiome was determined using 16S rRNA analysis. At the end of six months, Laser-Doppler Flowmetry was recorded from the palmar surface of the forepaw while maintaining the rat’s body temperature at 35–37oC with a heating blanket. Perfusion analysis was used to estimate the microvascular blood flow within the selected region of interest. The spectral composition of flowmotion was analysed with Continuous Wavelet Transform using the Morlet mother wavelet. We used the following published frequency bands for rats for the spectral analysis for the control of microvascular flowmotion: cardiac (2-5 Hz), respiratory (0.7-2 Hz), myogenic (0.2–0.7 Hz), neurogenic (0.08–0.2 Hz), and metabolic control (0.01–0.08 Hz). Statistical analyses were performed with SPSS using ANOVA and post-hoc analyses; p < 0.05 was considered statistically significant. The mean (±SEM) weights (g) of the rats after six months were: CON (537±44), PRE (510±54), CAF (640±43) and PRE-CAF (608±73); there was significant increase in weight of the CAF group compared to the CON, and of the PRE-CAF group compared to the PRE group. Skin perfusion was significantly lower in the CAF group compared to the CON group or the PRE-CAF group. Compared to the CON group, the CAF group had significant decreases in all the wavelet bands. Additionally, there were significant decreases in the myogenic, neurogenic and metabolic bands in the CAF group compared to the PRE-CAF group. There were no significant differences between the CON and PRE groups in the perfusion or any of the wavelet parameters. Analysis of the microbiome showed Allobaculum spp., Bifidobacterium spp. and Coriobacteriaceae UCG-02 were significantly more abundant in the prebiotic groups. Funding provided by UWI, Trinidad This is the full abstract presented at the American Physiology Summit 2023 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.