Multiple sclerosis (MS) is a progressive disease characterized by demyelination in the central nervous system which disproportionately impacts females. Previous studies suggest MS-related exercise intolerance may be due to abnormal control of arterial blood pressure (BP) via the skeletal muscle metaboreflex. However, few studies have been performed and equivocal results reported. Discontinuity in prior data may be due to limited perturbation of metaboreflex activation using only low and moderate intensity exercise. PURPOSE: The purpose of this investigation was to test the hypothesis that females with MS have blunted BP and sympathetic responses to graded static handgrip (HG) exercise and isolated metaboreflex activation during postexercise ischemia (PEI) compared to healthy controls. METHODS: In 7 females with relapsing-remitting MS and 9 healthy female controls beat-to-beat BP (finometer) and muscle sympathetic nerve activity (MSNA; peroneal microneurography) were recorded at rest and during two minutes of handgrip performed at 30% and 40% maximum voluntary contraction followed by two minutes of PEI to isolate the muscle metaboreflex. RESULTS: There were no differences in resting mean arterial pressure (MAP; P= 0.16) or MSNA burst frequency (P= 0.15) between MS and controls. MAP and MSNA increased during 30% HG (MS: Δ19.8 ± 9.1 mmHg vs. Con: Δ17.8 ± 5.4 mmHg; P= 0.30 and MS: Δ17 ± 12 bursts/min vs. Con: Δ18 ± 17 bursts/min; P= 0.46) and 40% HG (MS: Δ29.3 ± 8.0 mmHg vs. Con: Δ30.0 ± 6.9 mmHg; P= 0.43 and MS: Δ36 ± 16 bursts/min vs. Con: Δ40 ± 9 bursts/min; P= 0.30) with no differences between groups. Likewise, MAP and MSNA responses were also not different during PEI post 30% HG (MS: Δ15.8 ± 7.6 mmHg vs. Con: Δ15.8 ± 6.4 mmHg; P= 0.50 and MS: Δ15 ± 9 bursts/min vs. Con: Δ11 ± 7 bursts/min; P= 0.19) or PEI post 40% HG (MS: Δ25.8 ± 6.3 mmHg vs. Con: Δ22.6 ± 8.2 mmHg; P= 0.43 and MS: Δ23 ± 13 bursts/min vs. Con: Δ24 ± 7 bursts/min; P= 0.46) between MS and controls. CONCLUSION: These preliminary data suggest intact skeletal muscle metaboreflex control of arterial BP in females with MS.



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