Forearm vascular conductance responses to rhythmic handgrip in young Hispanic American adults compared to Caucasian American adults
Authors: Liu Randy , Nyarko Ruby , Perez Justo , Dalve Ashlesha , Van Wagoner Tyler , Appiah Crystal , Kaur Jasdeep 
Published: May 2023

Hispanic American (HA) individuals have double the prevalence and earlier onset of Type 2 Diabetes (T2D) compared to Caucasian American (CA) individuals. The underlying mechanisms for this disproportionately high incidence of T2D in HA individuals remains unknown. Impaired vascular dysfunction is a well-known hallmark of T2D however, very few studies have investigated vascular function in HA population. Equivocal results have been reported regarding flow-mediated dilation (FMD), a measure of endothelium-mediated, nitric oxide-dependent vasodilation in response to a cuff inflation, in HA population. In addition, vascular responsiveness during exercise has not been investigated in this racial group. Previous studies have indicated that exercise at increasing workloads elicits progressive increases in shear stress causing intensity-dependent vasodilation, which is primarily mediated by NO. Therefore, we aim to extend the previous findings by evoking a stepwise increase in shear stress during three exercise workloads to investigate the vascular function in HA adults during exercise. We tested the hypothesis that HA individuals would exhibit an attenuated forearm blood flow (FBF) and forearm vascular conductance (FVC) compared to CA individuals during RHG (rhythmic handgrip exercise). Forearm blood flow (duplex Doppler ultrasound), heart rate (ECG) and mean arterial pressure (MAP; finger photoplethysmography) were measured in young, healthy CA (n = 17 (7M/10F)) as well as in young, healthy HA (n = 13 (7M/6F)) during three trials of RHG performed at 15%, 30%, and 45% of their maximum voluntary contraction (MVC). As studies have reported sex differences in vascular function in HA previously, data will be presented in different sexes(Mean±standard deviation). In men, baseline FBF (CA: 121.1±45.6, HA: 98.7±34.5, p=0.28), MAP (CA: 84±6, HA: 85±7, p=0.47), FVC (calculated as FBF/MAP, p=0.28), and MVCs (CA: 79±15, HA: 74±17, p=0.19) were similar between groups. Similarly, in women, baseline FBF (CA: CA: 67.8±22.6, HA: 67.3±5.2, p=0.98), MAP (CA: 84±9, HA: 82±6, p=0.64), FVC (p=0.95), and MVC (CA: 49±6, HA: 53±13, p=0.21) were not different between groups. In men, an intensity-dependent increase in FVC and FBF was observed, with no difference between the racial groups (e.g., %Δ FVC 45%MVC CA=417±296% vs. HA=367±84% in HA; race effect p=0.40, intensity effect p<0.01, interaction p=0.32). Increase in MAP was also not significant (e.g., ΔMAP 45%MVC CA=8±5, HA=11±7, p=0.50) In women, a similar intensity-dependent increase in FVC and FBF was observed (e.g., %Δ FVC 45%MVC: 455±164% in CA, 418±104% in HA; race effect p=0.48, intensity effect p<0.01, interaction p=0.92). Increase in MAP was also not significant. (e.g., ΔMAP 45%MVC CA=15±8, HA=12±8, p=0.41) These preliminary findings indicate that vascular function during rhythmic handgrip exercise is preserved in Hispanic men and women, compared to their white counterparts. Kinesiology and Health Education UT Austin Start-Up Account 19-2635-91 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.