scholarly journals Nitric oxide, but not vasodilating prostaglandins, contributes to the improvement of exercise hyperemia via ascorbic acid in healthy older adults

2010 ◽  
Vol 299 (5) ◽  
pp. H1633-H1641 ◽  
Author(s):  
Anne R. Crecelius ◽  
Brett S. Kirby ◽  
Wyatt F. Voyles ◽  
Frank A. Dinenno

Acute ascorbic acid (AA) administration increases muscle blood flow during dynamic exercise in older adults, and this is associated with improved endothelium-dependent vasodilation. We directly tested the hypothesis that increase in muscle blood flow during AA administration is mediated via endothelium-derived vasodilators nitric oxide (NO) and prostaglandins (PGs). In 14 healthy older adults (64 ± 3 yr), we measured forearm blood flow (FBF; Doppler ultrasound) during rhythmic handgrip exercise at 10% maximum voluntary contraction. After 5-min steady-state exercise with saline, AA was infused via brachial artery catheter for 10 min during continued exercise, and this increased FBF ∼25% from 132 ± 16 to 165 ± 20 ml/min ( P < 0.05). AA was infused for the remainder of the study. Next, subjects performed a 15-min exercise bout in which AA + saline was infused for 5 min, followed by 5 min of the nitric oxide synthase (NOS) inhibitor NG-monomethyl-l-arginine (l-NMMA) and then 5 min of the cyclooxygenase inhibitor ketorolac ( group 1). The order of inhibition was reversed in eight subjects ( group 2). In group 1, independent NOS inhibition reduced steady-state FBF by ∼20% ( P < 0.05), and subsequent PG inhibition had no impact on FBF (Δ 3 ± 5%). Similarly, in group 2, independent PG inhibition had little effect on FBF (Δ −4 ± 4%), whereas subsequent NO inhibition significantly decreased FBF by ∼20% ( P < 0.05). In a subgroup of five subjects, we inhibited NO and PG synthesis before AA administration. In these subjects, there was a minimal nonsignificant improvement in FBF with AA infusion (Δ 7 ± 3%; P = nonsignificant vs. zero). Together, our data indicate that the increase in muscle blood flow during dynamic exercise with acute AA administration in older adults is mediated primarily via an increase in the bioavailability of NO derived from the NOS pathway.

2010 ◽  
Vol 109 (3) ◽  
pp. 768-777 ◽  
Author(s):  
William G. Schrage ◽  
Brad W. Wilkins ◽  
Christopher P. Johnson ◽  
John H. Eisenach ◽  
Jacqueline K. Limberg ◽  
...  

The vasodilator signals regulating muscle blood flow during exercise are unclear. We tested the hypothesis that in young adults leg muscle vasodilation during steady-state exercise would be reduced independently by sequential pharmacological inhibition of nitric oxide synthase (NOS) and cyclooxygenase (COX) with NG-nitro-l-arginine methyl ester (l-NAME) and ketorolac, respectively. We tested a second hypothesis that NOS and COX inhibition would increase leg oxygen consumption (V̇o2) based on the reported inhibition of mitochondrial respiration by nitric oxide. In 13 young adults, we measured heart rate (ECG), blood pressure (femoral venous and arterial catheters), blood gases, and venous oxygen saturation (indwelling femoral venous oximeter) during prolonged (25 min) steady-state dynamic knee extension exercise (60 kick/min, 19 W). Leg blood flow (LBF) was determined by Doppler ultrasound of the femoral artery. Whole body V̇o2 was measured, and leg V̇o2 was calculated from blood gases and LBF. Resting intra-arterial infusions of acetylcholine (ACh) and nitroprusside (NTP) tested inhibitor efficacy. Leg vascular conductance (LVC) to ACh was reduced up to 53 ± 4% by l-NAME + ketorolac infusion, and the LVC responses to NTP were unaltered. Exercise increased LVC from 4 ± 1 to 33.1 ± 2 ml·min−1·mmHg−1 and tended to decrease after l-NAME infusion (31 ± 2 ml·min−1·mmHg−1, P = 0.09). With subsequent administration of ketorolac LVC decreased to 29.6 ± 2 ml·min−1·mmHg−1 ( P = 0.02; n = 9). While exercise continued, LVC returned to control values (33 ± 2 ml·min−1·mmHg−1) within 3 min, suggesting involvement of additional vasodilator mechanisms. In four additional subjects, LVC tended to decrease with l-NAME infusion alone ( P = 0.08) but did not demonstrate the transient recovery. Whole body and leg V̇o2 increased with exercise but were not altered by l-NAME or l-NAME + ketorolac. These data indicate a modest role for NOS- and COX-mediated vasodilation in the leg of exercising humans during prolonged steady-state exercise, which can be restored acutely. Furthermore, NOS and COX do not appear to influence muscle V̇o2 in untrained healthy young adults.


2015 ◽  
Vol 309 (2) ◽  
pp. H360-H368 ◽  
Author(s):  
Jennifer C. Richards ◽  
Anne R. Crecelius ◽  
Dennis G. Larson ◽  
Frank A. Dinenno

Human aging is associated with reduced skeletal muscle perfusion during exercise, which may be a result of impaired endothelium-dependent dilation and/or attenuated ability to blunt sympathetically mediated vasoconstriction. Intra-arterial infusion of ascorbic acid (AA) increases nitric oxide-mediated vasodilation and forearm blood flow (FBF) during handgrip exercise in older adults, yet it remains unknown whether an acute oral dose can similarly improve FBF or enhance the ability to blunt sympathetic vasoconstriction during exercise. We hypothesized that 1) acute oral AA would improve FBF (Doppler ultrasound) and oxygen consumption (V̇o2) via local vasodilation during graded rhythmic handgrip exercise in older adults ( protocol 1), and 2) AA ingestion would not enhance sympatholysis in older adults during handgrip exercise ( protocol 2). In protocol 1 ( n = 8; 65 ± 3 yr), AA did not influence FBF or V̇o2 during rest or 5% maximal voluntary contraction (MVC) exercise, but increased FBF (199 ± 13 vs. 248 ± 16 ml/min and 343 ± 24 vs. 403 ± 33 ml/min; P < 0.05) and V̇o2 (26 ± 2 vs. 34 ± 3 ml/min and 43 ± 4 vs. 50 ± 5 ml/min; P < 0.05) at both 15 and 25% MVC, respectively. The increased FBF was due to elevations in forearm vascular conductance (FVC). In protocol 2 ( n = 10; 63 ± 2 yr), following AA, FBF was similarly elevated during 15% MVC (∼20%); however, vasoconstriction to reflex increases in sympathetic activity during −40 mmHg lower-body negative pressure at rest (ΔFVC: −16 ± 3 vs. −16 ± 2%) or during 15% MVC (ΔFVC: −12 ± 2 vs. −11 ± 4%) was unchanged. Our collective results indicate that acute oral ingestion of AA improves muscle blood flow and V̇o2 during exercise in older adults via local vasodilation.


2008 ◽  
Vol 22 (S1) ◽  
Author(s):  
Brett S Kirby ◽  
Wyatt F Voyles ◽  
Carrie B Simpson ◽  
Rick E Carlson ◽  
William G Schrage ◽  
...  

1997 ◽  
Vol 273 (1) ◽  
pp. H405-H410 ◽  
Author(s):  
R. C. Hickner ◽  
J. S. Fisher ◽  
A. A. Ehsani ◽  
W. M. Kohrt

The role of nitric oxide at rest and in the active hyperemic response within skeletal muscle was investigated in eight physically active men. Three microdialysis probes were inserted into the vastus lateralis of the quadriceps femoris muscle group in each subject. Microdialysis probes were perfused with a Ringer solution containing 5.0 mM ethanol, 2.5 mM glucose, and either 10 mg/ml of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) monoacetate salt, 30 mg/ml of the nitric oxide precursor L-arginine, or no additional substance (control probe). Subjects performed one-legged cycling exercise at work rates ranging from 25 to 100 W. Dialysate and perfusate ethanol concentrations were presented as the ratio of [ethanol]dialysate to [ethanol]perfusate (ethanol outflow-to-inflow ratio), an indicator that is inversely related to blood flow. The ethanol outflow-to-inflow ratios at rest were 0.614 +/- 0.032, 0.523 +/- 0.023, and 0.578 +/- 0.039 in the L-NMMA, L-arginine, and control probes, respectively. Calculated resting blood flows were therefore 8.7 +/- 4.1, 20.5 +/- 4.6, and 14.0 +/- 4.7 ml.min-1.100 g-1 around the L-NMMA, L-arginine, and control probes, respectively. The ethanol outflow-to-inflow ratios were significantly higher at all exercise intensities in the L-NMMA probe than in the control and L-arginine probes, resulting in calculated blood flows of 195 +/- 55, 407 +/- 47, and 352 +/- 60 ml.min-1.100 g-1 at 25 W and 268 +/- 65, 602 +/- 129, and 519 +/- 113 ml.min-1.100 g-1 at 100 W around the L-NMMA, L-arginine, and control probes, respectively. Skeletal muscle blood flow was therefore reduced both at rest and during continuous, dynamic exercise by the action of L-NMMA, whereas blood flow was increased only at rest by L-arginine.


2003 ◽  
Vol 284 (2) ◽  
pp. H668-H675 ◽  
Author(s):  
Jorge A. Guzman ◽  
Ariosto E. Rosado ◽  
James A. Kruse

Effects of a dopamine-1 (DA-1) receptor agonist on systemic and intestinal oxygen delivery (D˙o 2)-uptake relationships were studied in anesthetized dogs during sequential hemorrhage. Control ( group 1) and experimental animals ( group 2) were treated similarly except for the addition of fenoldopam (1.0 μg · kg−1 · min−1) in group 2. Both groups had comparable systemic criticalD˙o 2(D˙o 2crit), but animals in group 2 had a higher gut D˙o 2crit(1.12 ± 1.13 vs. 0.80 ± 0.09 ml · kg−1 · min−1, P < 0.05). At the mucosal level, a clear biphasic delivery-uptake relationship was not observed in group 1; thus oxygen consumption by the mucosa may be supply dependent under physiological conditions. Group 2 demonstrated higher peak mucosal blood flow and lack of supply dependency at higher mucosalD˙o 2 levels. Fenoldopam resulted in a more conspicuous biphasic relationship at the mucosa and a rightward shift of overall splanchnic D˙o 2crit despite increased splanchnic blood flow. These findings suggest that DA-1 receptor stimulation results in increased gut perfusion heterogeneity and maldistribution of perfusion, resulting in increased susceptibility to ischemia.


2011 ◽  
Vol 110 (5) ◽  
pp. 1181-1189 ◽  
Author(s):  
Darren P. Casey ◽  
Michael J. Joyner

We previously demonstrated that nitric oxide (NO) contributes to compensatory vasodilation in the contracting human forearm subjected to acute hypoperfusion. We examined the potential role of an adenosine-NO interaction to this response in 17 male subjects (25 ± 2 yr). In separate protocols subjects performed rhythmic forearm exercise (20% of maximum) while hypoperfusion was evoked by balloon inflation in the brachial artery above the elbow. Each trial included exercise before inflation, exercise with inflation, and exercise after deflation (3 min each). Forearm blood flow (FBF; ultrasound) and local [brachial artery catheter pressure (BAP)] and systemic [mean arterial pressure (MAP); Finometer] arterial pressure were measured. In protocol 1 ( n = 10), exercise was repeated during nitric oxide synthase inhibition [ NG-monomethyl-l-arginine (l-NMMA)] alone and during l-NMMA-aminophylline (adenosine receptor blockade) administration. In protocol 2, exercise was repeated during aminophylline alone and during aminophylline-l-NMMA. Forearm vascular conductance (FVC; ml·min−1·100 mmHg−1) was calculated from blood flow (ml/min) and BAP (mmHg). Percent recovery in FVC during inflation was calculated as (steady-state inflation + exercise value − nadir)/[steady-state exercise (control) value − nadir]. In protocol 1, percent recovery in FVC was 108 ± 8% during the control (no drug) trial. Percent recovery in FVC was attenuated with inhibition of NO formation alone (78 ± 9%; P < 0.01 vs. control) and was attenuated further with combined inhibition of NO and adenosine (58 ± 9%; P < 0.01 vs. l-NMMA). In protocol 2, percent recovery was reduced with adenosine receptor blockade (74 ± 11% vs. 113 ± 6%, P < 0.01) compared with control drug trials. Percent recovery in FVC was attenuated further with combined inhibition of adenosine and NO (48 ± 11%; P < 0.05 vs. aminophylline). Our data indicate that adenosine contributes to compensatory vasodilation in an NO-independent manner during exercise with acute hypoperfusion.


1988 ◽  
Vol 255 (5) ◽  
pp. H1004-H1010 ◽  
Author(s):  
D. E. Mohrman ◽  
R. R. Regal

We pump-perfused gastrocnemius-plantaris muscle preparations at constant pressure to study the relationship of muscle blood flow (Q) to muscle oxygen consumption (VO2), venous oxygen tension (PVO2), and venous carbon dioxide tension (PVCO2) during steady-state exercise at different rates. Tests were performed under four experimental conditions produced by altering the perfusate blood-gas status with a membrane lung. The consistency of the relationship of Q to other variables was evaluated by statistical analysis of fitted curves. Not one of the above listed variables had the same relationship with Q in all four of the experimental conditions we tested. However, we did find that a consistent relationship existed among Q, PVO2, and PVCO2 in our data. That relationship is well described by the equation (Q-23).[PVO2 - (0.5.PVCO2) - 3] = 105 (when Q is expressed in ml.100 g-1.min-1 and PVO2 and PVCO2 in mmHg). One interpretation of this result is that both PO2 and PCO2 are important variables in the control of blood flow in skeletal muscle the combined influence of which could account for nearly all of the hyperemia response to steady-state muscle exercise.


2004 ◽  
Vol 97 (3) ◽  
pp. 1130-1137 ◽  
Author(s):  
Csongor Csekő ◽  
Zsolt Bagi ◽  
Akos Koller

We hypothesized that hydrogen peroxide (H2O2) has a role in the local regulation of skeletal muscle blood flow, thus significantly affecting the myogenic tone of arterioles. In our study, we investigated the effects of exogenous H2O2 on the diameter of isolated, pressurized (at 80 mmHg) rat gracilis skeletal muscle arterioles (diameter of ∼150 μm). Lower concentrations of H2O2 (10−6–3 × 10−5 M) elicited constrictions, whereas higher concentrations of H2O2 (6 × 10−5–3 × 10−4 M), after initial constrictions, caused dilations of arterioles (at 10−4 M H2O2, −19 ± 1% constriction and 66 ± 4% dilation). Endothelium removal reduced both constrictions (to −10 ± 1%) and dilations (to 33 ± 3%) due to H2O2. Constrictions due to H2O2 were completely abolished by indomethacin and the prostaglandin H2/thromboxane A2 (PGH2/TxA2) receptor antagonist SQ-29548. Dilations due to H2O2 were significantly reduced by inhibition of nitric oxide synthase (to 38 ± 7%) but were unaffected by clotrimazole or sulfaphenazole (inhibitors of cytochrome P-450 enzymes), indomethacin, or SQ-29548. In endothelium-denuded arterioles, clotrimazole had no effect, whereas H2O2-induced dilations were significantly reduced by charybdotoxin plus apamin, inhibitors of Ca2+-activated K+ channels (to 24 ± 3%), the selective blocker of ATP-sensitive K+ channels glybenclamide (to 14 ± 2%), and the nonselective K+-channel inhibitor tetrabutylammonium (to −1 ± 1%). Thus exogenous administration of H2O2 elicits 1) release of PGH2/TxA2 from both endothelium and smooth muscle, 2) release of nitric oxide from the endothelium, and 3) activation of K+ channels, such as Ca2+-activated and ATP-sensitive K+ channels in the smooth muscle resulting in biphasic changes of arteriolar diameter. Because H2O2 at low micromolar concentrations activates several intrinsic mechanisms, we suggest that H2O2 contributes to the local regulation of skeletal muscle blood flow in various physiological and pathophysiological conditions.


2019 ◽  
Vol 34 (1) ◽  
pp. 54-60
Author(s):  
M. S. Kamenskikh ◽  
A. V. Zagatina ◽  
N. T. Zhuravskaya ◽  
Yu. N. Fedotov ◽  
D. V. Shmatov

Aim of the study was to identify the effects of myocardial revascularization on the prognosis in patients with altered coronary blood flow detected by transthoracic ultrasound.Material and Methods. Four hundred and twelve (412) patients were included in the study. The inclusion criterion was coronary velocity more than 70 cm/s during echocardiography. The study population was divided into three groups: Group 1 comprised patients with high velocities in the coronary arteries detected by ultrasound, in whom myocardial revascularization was performed; Group 2 comprised patients with high velocities in the coronary arteries, in whom myocardial revascularization was not performed and; the Control Group comprised patients with normal coronary blood flow according to ultrasound. The follow-up period was 10–11 months.Results. Seventeen (17) deaths (4.7%) occurred during follow-up. Death rates were 1.6 vs. 8.1 vs. 0% in Group 1, Group 2 and the Control Group, respectively, with a p-value for the difference between Group 1 and Group 2 (p1) of <0.009; and a p-value for the differences compared with the Control group (р2) of <0.03. Death, myocardial infarction, pulmonary edema, and acute coronary syndrome were observed in 27 patients (7.7% of the study group with accelerated blood flow). The rates of these outcomes were 4.9 vs. 11.0 vs. 0% in Group 1, Group 2, and the Control Group, respectively (p1<0.05; p2<0.006). Discussion. The study showed high rates of mortality or acute coronary events in the group of patients with pathologically high coronary flow velocities. The positive effects of revascularization on survival in this group were verified.Conclusions: 1. Left artery coronary flow velocities over 70 cm/s indicate a high probability of death or acute coronary events within 10.5 months.2. Myocardial revascularization has a significant positive effect on the survival rate and incidence of acute coronary events in patients with coronary artery flow velocities greater than 70 cm/s.3. Patients with high coronary blood flow velocities should be referred to coronary angiography or other diagnostic tests without waiting for clinical manifestations and specific symptoms for coronary artery disease.


2022 ◽  
Vol 24 (5) ◽  
pp. 440-447
Author(s):  
I. A. Khripun ◽  
S. V. Vorobyev

Background: Type 2 diabetes mellitus (T2DM) and hypogonadism are mutually aggravating diseases associated with the development and progression of cardiovascular pathology. The status of endothelial function in men with T2DM and hypogonadism hasn’t been studied.Aims: To assess the effect of hypogonadism on endothelial function in men with T2DM.Materials and methods: Patients underwent clinical studies, assessment of carbohydrate and lipid metabolism, the content of sex hormones (total testosterone (T), sex hormones binding globulin, free T, luteinizing hormone) and markers of endothelial function (nitric oxide (NO), endothelial nitric oxide synthase type 3 (eNOS3), endothelin, adhesion molecules ICAM-1, VCAM-1, p- and e-selectins, cadherin), ultrasound examinations of endothelium-dependent vasodilation (EDVD) of the brachial artery (BA) and carotid arteries with an assessment of the thickness of intima-media complex (TIM) were performed.Results: The study included 276 men with T2DM (age 54.0[49;60] years), who were divided into 2 groups: 1–124 patients with hypogonadism; 2–152 eugonadal patients. Reduction of the endothelial vasomotor function was detected in 32.4% of patients in the 2st group and in 55.3% of the 1nd group (χ2=6.1; p=0.01), which was associated with a decrease in EDVD by 29.8 % (p<0.001) and an increase in the time of development of maximal BA vasodilation by 30 seconds in patients with hypogonadism (p<0.001). The TIM of the carotid arteries was 10% more in group 1 compared with group 2 (p=0.03). The ­level of NO in the 1st group was reduced by 1.6 times (p=0.001), eNOS3–by 1.5 times (p=0.038) compared with the 2nd group. The concentrations of adhesion molecules were higher in group 1 compared to group 2: VCAM-1 by 32.5% (p<0.001), ICAM-1 by 43.5% (p<0.001), p-selectin–by 19.3% (p=0.004), cadherin–6 times (p<0.001).Conclusion: Hypogonadism in men with T2DM is associated with the development of endothelial dysfunction, which manifests in a weakening of the EDVD and a slowdown in its development, as well as disturbances of the secretory activity of endothelium–a decrease in NO synthesis and activation of the adhesion molecules expression, which can be regarded as an universal pathogenetic mechanism of the development of cardiovascular diseases in combination of T deficiency and T2DM.


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