title: The influence of reduced insulin sensitivity via short-term reductions in physical activity on cardiac baroreflex sensitivity during acute hyperglycemia.
abstract: Reduced insulin sensitivity and impaired glycemic control are among the consequences of physical inactivity and have been associated with reduced cardiac baroreflex sensitivity (BRS). However, the effect of reduced insulin sensitivity and acute hyperglycemia following glucose consumption on cardiac BRS in young, healthy subjects has not been well characterized. We hypothesized that a reduction in insulin sensitivity via reductions in physical activity would reduce cardiac BRS at rest and following an oral glucose tolerance test (OGTT). Nine recreationally active men (23 ± 1 yr; >10,000 steps/day) underwent 5 days of reduced daily physical activity (RA5) by refraining from planned exercise and reducing daily steps (<5,000 steps/day). Spontaneous cardiac BRS (sequence technique) was compared at rest and for 120 min following an OGTT at baseline and after RA5. A substudy (n = 8) was also performed to independently investigate the influence of elevated insulin alone on cardiac BRS using a 120-min hyperinsulinemic-euglycemic clamp. Insulin sensitivity (Matsuda index) was significantly reduced following RA5 (BL 9.2 ± 1.3 vs. RA5 6.4 ± 1.1, P < 0.001). Resting cardiac BRS was unaffected by RA5 and significantly reduced during the OGTT similarly at baseline and RA5 (baseline 0 min, 28 ± 4 vs. 120 min, 18 ± 4; RA5 0 min, 28 ± 4 vs. 120 min, 21 ± 3 ms/mmHg). Spontaneous cardiac BRS was also reduced during the hyperinsulinemic-euglycemic clamp (P < 0.05). Collectively, these data demonstrate that acute elevations in plasma glucose and insulin can impair spontaneous cardiac BRS in young, healthy subjects, and that reductions in cardiac BRS following acute hyperglycemia are unaffected by reduced insulin sensitivity via short-term reductions in physical activity.
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: S W
authors.initials: SW
authors.lastname: Holwerda
authors.affiliation: Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky;
authors.forename: L J
authors.initials: LJ
authors.lastname: Reynolds
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: R M
authors.initials: RM
authors.lastname: Restaino
authors.affiliation: School of Kinesiology, University of Southern Mississippi, Hattiesburg, Mississippi; and.
authors.forename: D P
authors.initials: DP
authors.lastname: Credeur
authors.affiliation: Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri;
authors.forename: H J
authors.initials: HJ
authors.lastname: Leidy
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: J P
authors.initials: JP
authors.lastname: Thyfault
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; fadelp@uta.edu.
authors.forename: P J
authors.initials: PJ
authors.lastname: Fadel
mesh_terms: D000208:Acute Disease; D017704:Baroreflex; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D009043:Motor Activity; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin
keywords: arterial baroreflex; blood pressure; insulin resistance; oral glucose tolerance test