title: Carbohydrate ingestion induces sex-specific cardiac vagal inhibition, but not vascular sympathetic modulation, in healthy older women.
abstract: The role of vagal function in cardiovascular risk in older women remains unclear. Autonomic modulation following carbohydrate ingestion (CI) and postural stress (PS) were investigated in 14 healthy men and 21 age-matched postmenopausal women (age: 65.0 ± 2.1 vs. 64.1 ± 1.6 years), with normal and comparable insulin sensitivity. Continuous noninvasive finger arterial pressure and ECG were recorded in the lying and the standing positions before and after ingestion of a carbohydrate-rich meal (600 kcal, carbohydrate 78%, protein 13%, and fat 8%). Low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.4 Hz) components (ms(2)) of heart rate variability (HRV), low-frequency power (mmHg(2)) of systolic blood pressure variability (SBP LF power), and the sequence method for spontaneous baroreflex sensitivity (BRS, ms/mmHg) were used to quantify autonomic modulation. In response to CI and PS, mean arterial pressure maintained stable, and heart rate increased in women and men in the lying and standing positions. Following CI (60, 90, and 120 min postprandially) in the standing position, SBP LF power increased by 40% in men (P = 0.02), with unchanged HRV parameters; in contrast, in women, HRV HF power halved (P = 0.02), with unaltered SBP LF power. During PS before and after CI, similar magnitude of SBP LF power, HRV, and BRS changes was observed in men and women. In conclusion, CI induces sex-specific vascular sympathetic activation in healthy older men, and cardiac vagal inhibition in healthy older women; this CI-mediated efferent vagal inhibition may suggest differential cardiovascular risk factors in women, irrespective of insulin resistance, and impairment of autonomic control.
authors.affiliation: The Heart Research Institute and The University of Sydney, New South Wales, Australia; and.
authors.forename: Lei
authors.initials: L
authors.lastname: Cao
authors.affiliation: Australian School of Advanced Medicine, Macquarie University, New South Wales, Australia.
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Graham
authors.affiliation: The Heart Research Institute and The University of Sydney, New South Wales, Australia; and paul.pilowsky@hri.org.au.
authors.forename: Paul M
authors.identifier: 0000-0003-3500-467X
authors.initials: PM
authors.lastname: Pilowsky
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D001808:Blood Vessels / Q000187:drug effects / Q000294:innervation*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D011187:Posture; D012727:Sex Characteristics; D013564:Sympathetic Nervous System / Q000187:drug effects*; D014630:Vagus Nerve / Q000187:drug effects*
chemical_list: D004040:Dietary Carbohydrates
keywords: aging; autonomic modulation; insulin sensitivity; orthostatic; postprandial; sex