Recently, it has been reported that dietary supplementation with grape seed extract (GSE) ameliorates endothelial function and increase nitric oxide (NO) bioavailability. Thus, we investigated if elevated blood pressure and aortic stiffness (AoS) characterized in obese individuals are attenuated following acute GSE supplementation. Twenty men (obese510; normal body weight (NBW)510) participated in this study. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR), and AoS were compared 2 h after ingestion of GSE or placebo (PL) on different days, 1 wk apart. Compared with the PL, GSE supplementation significantly decreased SBP (NBW: 10364 vs. 9963 mmHg; obese: 11863 vs. 11265 mmHg) and MAP (NBW: 7562 vs. 7262 mmHg; obese: 8663 vs. 8463 mmHg) in both groups, while there were no differences in HR, SV, DBP, TPR, and AoS. GSE supplementation significantly decreased CO in only obese group. In NBW group, TPR tended to be decreased, but there was no significant difference. Our study suggests that acute supplementation with GSE reduced both SBP and MAP via a reduction in CO in obese individuals and decreased peripheral vasoconstriction in NBW group.
Muscle sympathetic nerve activity (MSNA) increases during hyperinsulinemia, primarily attributed to central nervous system effects. Whether peripheral vasodilation induced by insulin further contributes to increased MSNA via arterial baroreflex-mediated mechanisms requires further investigation. Accordingly, we examined baroreflex modulation of the MSNA response to hyperinsulinemia. We hypothesized that rescuing peripheral resistance with co-infusion of the vasoconstrictor phenylephrine would attenuate the MSNA response to hyperinsulinemia. We further hypothesized the insulin-mediated increase in MSNA would be recapitulated with another vasodilator (sodium nitroprusside, SNP). Methods: In 33 young healthy adults (28M/5F), MSNA (microneurography) and arterial blood pressure (BP, Finometer/brachial catheter) were measured, and total peripheral resistance (TPR, ModelFlow) and baroreflex sensitivity were calculated at rest and during intravenous infusion of insulin (n=20) or SNP (n=13). A subset of participants receiving insulin (n=7) were co-infused with phenylephrine. Results: Insulin infusion decreased TPR (p=0.01) and increased MSNA (p<0.01), with no effect on arterial baroreflex sensitivity or BP (p>0.05). Co-infusion with phenylephrine returned TPR and MSNA to baseline, with no effect on arterial baroreflex sensitivity (p>0.05). Similar to insulin, SNP decreased TPR (p<0.05) and increased MSNA (p<0.01), with no effect on arterial baroreflex sensitivity (p>0.05). Conclusions: Acute hyperinsulinemia shifts the baroreflex stimulus-response curve to higher MSNA without changing sensitivity, likely due to insulin's peripheral vasodilatory effects. Results show peripheral vasodilation induced by insulin contributes to increased MSNA during hyperinsulinemia.
Herein we report in a sample of healthy young men (n=14) and women (n=12) that hyperinsulinemia induces time-dependent decreases in total peripheral resistance and its contribution to the maintenance of blood pressure. In the same participants, we observe profound vasodilatory effects of insulin in the lower limb despite concomitant activation of the sympathetic nervous system. We hypothesized this prominent peripheral vasodilation is possibly due to an ability of the leg vasculature to escape sympathetic vasoconstriction during systemic insulin stimulation. Consistent with this notion, we demonstrate in a subset of healthy men (n=9) and women (n=7) that systemic infusion of insulin blunts sympathetically-mediated leg vasoconstriction evoked by a cold pressor test, a well-established sympathoexcitatory stimulus. Further substantiating this observation, we show in mouse aortic rings that insulin exposure suppresses epinephrine and norepinephrine-induced vasoconstriction. Notably, we found that such insulin-suppressing effects on catecholamine-induced constriction are diminished following β-adrenergic receptor blockade. In accordance, we also reveal that insulin augments β-adrenergic-mediated vasodilation in isolated arteries. Collectively, these findings support the idea that sympathetic vasoconstriction can be attenuated during systemic hyperinsulinemia in the leg vasculature of both men and women and that this phenomenon may be in part mediated by potentiation of β-adrenergic vasodilation neutralizing α-adrenergic vasoconstriction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.