| Autor: |
McMillan NJ; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States.; NextGen Precision Health, University of Missouri, Columbia, Missouri, United States., Jacob DW; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States., Shariffi B; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States., Harper JL; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States., Foster GE; School of Health and Exercise Sciences, Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, Canada., Manrique-Acevedo C; NextGen Precision Health, University of Missouri, Columbia, Missouri, United States.; Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Missouri, Columbia, Missouri, United States.; Research Services, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri, United States., Padilla J; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States.; NextGen Precision Health, University of Missouri, Columbia, Missouri, United States.; Research Services, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri, United States., Limberg JK; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States.; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States. |
| Abstrakt: |
Systemic insulin increases muscle sympathetic nerve activity (MSNA) via both central actions within the brainstem and peripheral activation of the arterial baroreflex. Augmented MSNA during hyperinsulinemia likely restrains peripheral vasodilation and contributes to the maintenance of blood pressure (BP). However, in the absence of insulin action within the peripheral vasculature, whether central insulin stimulation increases MSNA and influences peripheral hemodynamics in humans remains unknown. Herein, we hypothesized intranasal insulin administration would increase MSNA and BP in healthy young adults. Participants were assigned to time control [TC, n = 13 (5 females/8 males), 28 ± 1 yr] or 160 IU of intranasal insulin administered over 5 min [ n = 15 (5 females/10 males), 26 ± 2 yr]; five (1 female/4 males) participants completed both conditions. MSNA (fibular microneurography), BP (finger photoplethysmography), and leg blood flow (LBF, femoral Doppler ultrasound) were assessed at baseline, and 15 and 30 min following insulin administration. Leg vascular conductance [LVC = (LBF ÷ mean BP) × 100] was calculated. Venous insulin and glucose concentrations remained unchanged throughout ( P > 0.05). Following intranasal insulin administration, MSNA (burst frequency; baseline = 100%; minute 15 , 121 ± 8%; minute 30 , 118 ± 6%; P = 0.009, n = 7) and mean BP (baseline = 100%; minute 15 , 103 ± 1%; minute 30 , 102 ± 1%; P = 0.003) increased, whereas LVC decreased (baseline = 100%; minute 15 , 93 ± 3%; minute 30 , 99 ± 3%; P = 0.03). In contrast, MSNA, mean BP, and LVC were unchanged in TC participants ( P > 0.05). We provide the first evidence that intranasal insulin administration in healthy young adults acutely increases MSNA and BP and decreases LVC. These results enhance mechanistic understanding of the sympathetic and peripheral hemodynamic response to insulin. NEW & NOTEWORTHY Systemic insulin increases muscle sympathetic nerve activity (MSNA) via central actions within the brainstem and peripheral activation of the arterial baroreflex. In the absence of peripheral insulin action, whether central insulin stimulation increases MSNA and influences peripheral hemodynamics in humans was unknown. We provide the first evidence that intranasal insulin administration increases MSNA and blood pressure and reduces leg vascular conductance. These results enhance mechanistic understanding of the sympathetic and hemodynamic response to insulin. |
