title: Plasma nitrate/nitrite response to an oral glucose load and the effect of endurance training.
abstract: To assess the role of circulating nitric oxide (NO) production in glucose homeostasis, plasma nitrate/nitrite (NO(x)) was assessed during oral glucose tolerance tests (OGTTs) on 64 sedentary subjects and in a subset 40 subjects before and after 6 months of endurance exercise training. NO(x) decreased with the oral glucose load (P </=.001 for linear and quadratic effects). OGTT NO(x) response indices (NO(x) response area (NO(x) AREA), change in NO(x) from baseline to the minimum (DeltaNO(x)), and NO(x) time-to-minimum) were not associated with OGTT insulin or glucose areas under the curve (AUCs) or with insulin sensitivity index (ISI). Training did not alter NO(x) AREA, or DeltaNO(x), however, NO(x) time-to-minimum occurred later after training (P =.038). Training-induced insulin AUC and ISI changes were not associated with OGTT NO(x) index changes; however, glucose total AUC changes were associated with changes in NO(x) AREA (r =.42, P =.007) and DeltaNO(x) (r =.37, P =.019). In conclusion, these data suggest that circulating NO production is not involved in glycemic control after an oral glucose load in sedentary adults. In response to endurance training, however, it appears that the time required to reach minimum NO(x) levels after a glucose load is greater after training. Furthermore, although the magnitude of NO(x) response (as indicated by NO(x) AREA and DeltaNO(x)) to an oral glucose load does not appear to change with training for all individuals, individual training-induced changes in the NO(x) response magnitude are partly explained by training-induced changes in OGTT glucose responses.
authors.affiliation: Department of Kinesiology, University of Maryland, College Park, MD, USA.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Weiss
authors.forename: Jung-Jun
authors.initials: JJ
authors.lastname: Park
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: McKenzie
authors.forename: Joon-Young
authors.initials: JY
authors.lastname: Park
authors.forename: Onanong
authors.initials: O
authors.lastname: Kulaputana
authors.forename: Michael D
authors.initials: MD
authors.lastname: Brown
authors.forename: Dana A
authors.initials: DA
authors.lastname: Phares
authors.forename: James M
authors.initials: JM
authors.lastname: Hagberg
mesh_terms: D000284:Administration, Oral; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000097:blood*; D009573:Nitrites / Q000097:blood*; D010807:Physical Endurance / Q000502:physiology*; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin; D009566:Nitrates; D009573:Nitrites; D005947:Glucose