Abstract
Objective: Given recent evidence from rodents supporting a novel role for the carotid bodies in insulin‐mediated sympathoexcitation, we sought to determine whether carotid chemoreceptor desensitization would reduce muscle sympathetic nerve activity (MSNA) during hyperinsulinemia in humans. Methods: Young, healthy subjects (n=4, 30±2 yrs) breathed hyperoxic gas (End‐tidal O2 = 100%, PaO2 505±13 mmHg) for 15 min at baseline and during steady‐state hyperinsulinemia (5±1 vs 53±1 µU/mL). Hyperinsulinemia was achieved using a 90‐min hyperinsulinemic (1 mU/kg FFM/min), euglycemic (108±4 mg/dL) clamp. CO2 was maintained at resting levels (PaCO2 41±1 mmHg). Changes in heart rate, blood pressure, minute ventilation, and MSNA (microneurography of the peroneal nerve) were assessed. Results: Hyperinsulinemia increased MSNA [burst frequency (p<0.01), burst incidence (p=0.02), total activity (p=0.02)]. Hyperoxia decreased heart rate (p=0.01) and minute ventilation (p=0.11), and increased mean blood pressure (p=0.04). Consistent with our hypothesis, the effect of hyperoxia on MSNA (Δ) was different between baseline and hyperinsulinemia (burst frequency, p=0.03; burst incidence, p=0.10). Conclusion: These data are the first to suggest the carotid chemoreceptors may contribute to insulin‐mediated sympathoexcitation in humans.Grant Funding Source: Supported by: NIH R01 DK090541 (MJJ), NIH T32 DK07352 (JKL)
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