scholarly journals Effects of 1 MHz Therapeutic Ultrasound on Limb Blood Flow and Microvascular Reactivity: A Randomized Pilot Trial

2021 ◽  
Vol 18 (21) ◽  
pp. 11444
Author(s):  
Megan Waters ◽  
Branko Miljkovic ◽  
Jozelyn Rascon ◽  
Manuel Gomez ◽  
Alvaro N. Gurovich
Keyword(s):  
Blood Flow ◽  
Repeated Measures ◽  
Forearm Blood Flow ◽  
Pilot Trial ◽  
Therapeutic Ultrasound ◽  
Venous Occlusion ◽  
Double Blind ◽  
Effective Treatment Modality ◽  
Group Time ◽  
Before And After

A randomized, double-blind, placebo-controlled, cross-over study where continuous therapeutic ultrasound (CUS; at 0.4 W/cm2), pulsed therapeutic ultrasound (PUS; at 20% duty cycle, 0.08 W/cm2), both at 1 MHz, and placebo (equipment on, no energy provided) were randomized and applied over the forearm of the non-dominant arm for 5 min in 10 young, healthy individuals. Absolute and peak forearm blood flow (FBF) were measured via Venous Occlusion Plethysmography. FBF was measured before, halfway, and after (immediately and 5 min after) the therapeutic ultrasound (TUS) intervention. Post-ischemic peak FBF was measured 10 min before and 10 min after the TUS intervention. A two-way repeated measures ANOVA (group × time) was selected to assess differences in FBF before, during, and after TUS treatment, and for peak FBF before and after TUS treatment. FBF increased 5 min after TUS in CUS compared to placebo (2.96 ± 1.04 vs. 2.09 ± 0.63 mL/min/100 mL of tissue, p < 0.05). PUS resulted in the greatest increase in Peak FBF at 10 min after US (Δ = 3.96 ± 2.02 mL/min/100 mL of tissue, p = 0.06). CUS at 1 MHz was an effective treatment modality for increasing FBF up to 5 min after intervention, but PUS resulted in the greatest increase in peak FBF at 10 min after intervention.

Vascular KATP channel blockade by glibenclamide, but not by acarbose, in patients with Type II diabetes

2002 ◽  
Vol 102 (3) ◽  
pp. 307-314
Author(s):  
E.J. ABBINK ◽  
P. PICKKERS ◽  
A. Jansen VAN ROSENDAAL ◽  
J.A. LUTTERMAN ◽  
C.J. TACK ◽  
...  
Keyword(s):  
Blood Flow ◽  
Type Ii Diabetes ◽  
Katp Channel ◽  
Forearm Blood Flow ◽  
Cardiovascular Effects ◽  
Venous Occlusion ◽  
Type Ii Diabetes Mellitus ◽  
Protective Mechanism ◽  
Type Ii ◽  
Double Blind

Glibenclamide inhibits the opening of vascular ATP-sensitive potassium (KATP) channels, which represents a protective mechanism during ischaemia. This effect may imply harmful cardiovascular effects of glibenclamide when used under conditions of ischaemia in patients with Type II diabetes. Acarbose is not associated with effects on the cardiovascular system, because the drug is not absorbed from the bowel. Therefore we hypothesized that treatment of Type II diabetes patients with glibenclamide will impair the vasodilator function of KATP opening, unlike treatment with acarbose. A double-blind randomized cross-over study in 12 patients with Type II diabetes was performed to compare the effects of glibenclamide with those of acarbose on the vasodilator responses to KATP channel opening in the forearm vascular bed. The study consisted of two periods: 8 weeks of treatment with orally administered glibenclamide (10mgċday-1) followed by 8 weeks of treatment with acarbose (300mgċday-1), or vice versa. At the end of each treatment period, forearm blood flow (venous occlusion plethysmography) in response to intra-arterially administered diazoxide, acetylcholine and dipyridamole and to forearm ischaemia was measured. The diazoxide-mediated increase in the forearm blood flow ratio (infused/control arm) was significantly less pronounced after glibenclamide than after acarbose (290±58% and 561±101% respectively; P < 0.0005). Forearm blood flow responses to acetylcholine, dipyridamole and forearm ischaemia were similar during glibenclamide and acarbose treatment. Thus, in patients with Type II diabetes mellitus, treatment with glibenclamide is associated with an attenuated response to KATP opening as compared with treatment with acarbose. This implies that glibenclamide may affect defensive mechanisms under conditions of KATP channel activation.

Hypercapnia-induced cerebral and ocular vasodilation is not altered by glibenclamide in humans

2000 ◽  
Vol 278 (6) ◽  
pp. R1667-R1673 ◽  
Author(s):  
Michaela Bayerle-Eder ◽  
Michael Wolzt ◽  
Elzbieta Polska ◽  
Herbert Langenberger ◽  
Johannes Pleiner ◽  
...  
Keyword(s):  
Blood Flow ◽  
Crossover Study ◽  
Flow Velocity ◽  
Forearm Blood Flow ◽  
Resistive Index ◽  
Venous Occlusion ◽  
Mean Flow ◽  
Choroidal Blood Flow ◽  
Double Blind ◽  
Induced Changes

Carbon dioxide is an important regulator of vascular tone. Glibenclamide, an inhibitor of ATP-sensitive potassium channel (KATP) activation, significantly blunts vasodilation in response to hypercapnic acidosis in animals. We investigated whether glibenclamide also alters the cerebral and ocular vasodilator response to hypercapnia in humans. Ten healthy male subjects were studied in a controlled, randomized, double-blind two-way crossover study under normoxic and hypercapnic conditions. Glibenclamide (5 mg po) or insulin (0.3 mU ⋅ kg− 1 ⋅ min− 1iv) were administered with glucose to achieve comparable plasma insulin levels. In control experiments, five healthy volunteers received glibenclamide (5 mg) or nicorandil (40 mg) or glibenclamide and nicorandil in a randomized, three-way crossover study. Mean blood flow velocity and resistive index in the middle cerebral artery (MCA) and in the ophthalmic artery (OA) were measured with Doppler sonography. Pulsatile choroidal blood flow was assessed with laser interferometric measurement of fundus pulsation. Forearm blood flow was measured with venous occlusion plethysmography. Hypercapnia increased ocular fundus pulsation amplitude by +18.2–22.3% ( P < 0.001) and mean flow velocity in the MCA by +27.4–33.3% ( P < 0.001), but not in the OA (2.1–6.5%, P = 0.2). Forearm blood flow increased by 78.2% vs. baseline ( P = 0.041) after nicorandil administration. Glibenclamide did not alter hypercapnia-induced changes in cerebral or ocular hemodynamics and did not affect systemic hemodynamics or forearm blood flow but significantly increased glucose utilization and blunted the nicorandil-induced vasodilation in the forearm. This suggests that hypercapnia-induced changes in the vascular beds under study are not mediated by activation of KATPchannels in humans.

scholarly journals Continuous release of vasodilator prostanoids contributes to regulation of resting forearm blood flow in humans

1998 ◽  
Vol 274 (4) ◽  
pp. H1174-H1183 ◽  
Author(s):  
Stephen J. Duffy ◽  
Binh T. Tran ◽  
Gishel New ◽  
Ronald N. Tudball ◽  
Murray D. Esler ◽  
...  
Keyword(s):  
Blood Flow ◽  
Forearm Blood Flow ◽  
Venous Occlusion ◽  
Continuous Release ◽  
Before And After ◽  
Prostaglandin F ◽  
Resting Tone ◽  
Dose Dependent ◽  
Prostacyclin Production

Continuous release of nitric oxide contributes to the maintenance of resting tone in the human forearm and coronary circulations; however, evidence for a similar role of vasodilator prostanoids such as prostacyclin is lacking. We examined whether continuous release of prostacyclin contributes to basal forearm blood flow. Flow was measured using venous occlusion plethysmography in 38 healthy volunteers [mean age 21.3 ± 2.5 yr (±SD); 13 female, 25 male] at rest, after administration of three incremental intra-arterial infusions of either the cyclooxygenase inhibitor aspirin or placebo, and before and after administration of the endothelium-dependent and -independent dilators acetylcholine (30 μg/min) and nitroprusside (1 μg/min). To assess the effect of aspirin on the production of prostacyclin, plasma 6-keto prostaglandin F1α(6-keto-PGF1α; the stable metabolite of prostacyclin) was measured by simultaneous arterial and venous sampling. Aspirin produced a time- and dose-dependent reduction in forearm blood flow, resulting in a 32% decrease at the highest dose. The effect was maximal after 10 min. Flow at rest and after aspirin doses of 1, 3, and 10 mg/min was 2.6 ± 0.2, 2.3 ± 0.2, 2.1 ± 0.2, and 1.8 ± 0.2 ml ⋅ 100 ml forearm tissue−1 ⋅ min−1, respectively (means ± SE, P< 0.001). Commensurate with these data, the net forearm production of 6-keto-PGF1α was 52.9 ± 16.4, 11.7 ± 8.6, 18.7 ± 8.5, and 12.0 ± 12.5 pg ⋅ 100 ml forearm tissue−1 ⋅ min−1 for the respective doses ( P = 0.04). No time-dependent reduction in flow was seen in subjects with vehicle infusion. Aspirin did not affect the responses to acetylcholine or nitroprusside. These data suggest that continuous release of prostacyclin plays a role in the maintenance of resting forearm blood flow. There appears to be a direct link between the reduction in flow with aspirin and inhibition of prostacyclin production.

scholarly journals Limb Blood Flow After Class 4 Laser Therapy

2012 ◽  
Vol 47 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Kelly A. Larkin ◽  
Jeffrey S. Martin ◽  
Elizabeth H. Zeanah ◽  
Jerry M. True ◽  
Randy W. Braith ◽  
...  
Keyword(s):  
Blood Flow ◽  
Laser Therapy ◽  
Repeated Measures ◽  
Soft Tissues ◽  
Biceps Brachii ◽  
Grid Point ◽  
Dose Range ◽  
Venous Occlusion ◽  
Effective Treatment Modality ◽  
Over Time

Context: Laser therapy is purported to improve blood flow in soft tissues. Modulating circulation would promote healing by controlling postinjury ischemia, hypoxia, edema, and secondary tissue damage. However, no studies have quantified these responses to laser therapy. Objective: To determine a therapeutic dose range for laser therapy for increasing blood flow to the forearm. Design: Crossover study. Setting: Controlled laboratory setting. Patients or Other Participants: Ten healthy, college-aged men (age = 20.80 ± 2.16 years, height = 177.93 ± 3.38 cm, weight = 73.64 ± 9.10 kg) with no current history of injury to the upper extremity or cardiovascular conditions. Intervention(s): A class 4 laser device was used to treat the biceps brachii muscle. Each grid point was treated for 3 to 4 seconds, for a total of 4 minutes. Each participant received 4 doses of laser therapy: sham, 1 W, 3 W, and 6 W. Main Outcome Measure(s): The dependent variables were changes in blood flow, measured using venous occlusion plethysmography. We used a repeated-measures analysis of variance to analyze changes in blood flow for each dose at 2, 3, and 4 minutes and at 1, 2, 3, 4, and 5 minutes after treatment. The Huynh-Feldt test was conducted to examine differences over time. Results: Compared with baseline, blood flow increased over time with the 3-W treatment (F3,9 = 3.468, P &lt; .011) at minute 4 of treatment (2.417 ± 0.342 versus 2.794 ± 0.351 mL/min per 100 mL tissue, P = .032), and at 1 minute (2.767 ± 0.358 mL/min per 100 mL tissue, P &lt; .01) and 2 minutes (2.657 ± 0.369 mL/min per 100 mL tissue, P = .022) after treatment. The sham, 1-W, and 6-W treatment doses did not change blood flow from baseline at any time point. Conclusions: Laser therapy at the 3-W (360-J) dose level was an effective treatment modality to increase blood flow in the soft tissues.

Effects of age and acclimation on responses to passive heat exposure

1993 ◽  
Vol 75 (5) ◽  
pp. 2162-2167 ◽  
Author(s):  
C. G. Armstrong ◽  
W. L. Kenney
Keyword(s):  
Blood Flow ◽  
Forearm Blood Flow ◽  
Heat Exposure ◽  
Heat Acclimation ◽  
Baseline Period ◽  
Venous Occlusion ◽  
Dew Point ◽  
Mean Body Temperature ◽  
Lower Baseline ◽  
Before And After

To examine the effect of chronological age on thermoregulation during passive heat exposure, six older (O, 61 +/- 1 yr) and six young (Y, 26 +/- 2 yr) men sat at rest during a 30-min baseline period (dry-bulb temperature = 28 degrees C), a 60-min thermal transient (28–46 degrees C by 2 degrees C steps every 5 min), and 30 min at 46 degrees C dry-bulb temperature. Subjects were matched for maximal O2 consumption, anthropometry, and body composition. Testing was repeated after a 9-day active heat acclimation protocol. There were no age differences in rectal (Tre), mean skin (Tsk), or mean body temperature (Tb = 0.8Tre + 0.2Tsk) before or after acclimation, but heart rate was lower (P < 0.01) in the O group in both acclimation states. Heat acclimation resulted in a significantly lower baseline Tre and Tb in both groups, which remained lower throughout the passive heat stress (P < 0.05). To examine the effects of age and acclimation on thermoregulatory effector function, forearm blood flow (by venous occlusion plethysmography) and chest sweating rate (SRch, by dew-point hygrometry) were plotted against Tb. The slope of the forearm blood flow-Tb relationship was significantly (P < 0.05) lower in the O group before and after acclimation. A lower maximal SRch (P < 0.05) was achieved by the O group, but neither the slope of SRch-Tb relationship nor the Tb threshold for sweating was affected by age. Predictably, acclimation resulted in a lower Tb threshold for the onset of sweating and skin vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of prostaglandins to modulate the time course of blood flow during dynamic forearm exercise in humans

1996 ◽  
Vol 81 (4) ◽  
pp. 1516-1521 ◽  
Author(s):  
J. K. Shoemaker ◽  
H. L. Naylor ◽  
Z. I. Pozeg ◽  
R. L. Hughson
Keyword(s):  
Blood Flow ◽  
Brachial Artery ◽  
Time Course ◽  
Forearm Blood Flow ◽  
Voluntary Contraction ◽  
Double Blind ◽  
Rate Of Increase ◽  
Forearm Exercise ◽  
Blind Manner ◽  
Exercise In Humans

Shoemaker, J. K., H. L. Naylor, Z. I. Pozeg, and R. L. Hughson. Failure of prostaglandins to modulate the time course of blood flow during dynamic forearm exercise in humans. J. Appl. Physiol. 81(4): 1516–1521, 1996.—The time course and magnitude of increases in brachial artery mean blood velocity (MBV; pulsed Doppler), diameter ( D; echo Doppler), mean perfusion pressure (MPP; Finapres), shear rate (γ˙ = 8 ⋅ MBV/ D), and forearm blood flow (FBF = MBV ⋅ π r 2) were assessed to investigate the effect that prostaglandins (PGs) have on the hyperemic response on going from rest to rhythmic exercise in humans. While supine, eight healthy men performed 5 min of dynamic handgrip exercise by alternately raising and lowering a 4.4-kg weight (∼10% maximal voluntary contraction) with a work-to-rest cycle of 1:1 (s/s). When the exercise was performed with the arm positioned below the heart, the rate of increase in MBV and γ˙ was faster compared with the same exercise performed above the heart. Ibuprofen (Ibu; 1,200 mg/day, to reduce PG-induced vasodilation) and placebo were administered orally for 2 days before two separate testing sessions in a double-blind manner. Resting heart rate was reduced in Ibu (52 ± 3 beats/min) compared with placebo (57 ± 3 beats/min) ( P < 0.05) without change to MPP. With placebo, D increased in both arm positions from ∼4.3 mm at rest to ∼4.5 mm at 5 min of exercise ( P < 0.05). This response was not altered with Ibu ( P > 0.05). Ibu did not alter the time course of MBV or forearm blood flow ( P > 0.05) in either arm position. The γ˙ was significantly greater in Ibu vs. placebo at 30 and 40 s of above the heart exercise and for all time points after 25 s of below the heart exercise ( P < 0.05). Because PG inhibition altered the time course ofγ˙ at the brachial artery, but not FBF, it was concluded that PGs are not essential in regulating the blood flow responses to dynamic exercise in humans.

Peak calf blood flow estimates are higher with Dohn than with Whitney plethysmograph

1996 ◽  
Vol 81 (3) ◽  
pp. 1418-1422 ◽  
Author(s):  
D. N. Proctor ◽  
J. R. Halliwill ◽  
P. H. Shen ◽  
N. E. Vlahakis ◽  
M. J. Joyner
Keyword(s):  
Blood Flow ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Venous Occlusion ◽  
Calf Blood Flow ◽  
Absolute Flow ◽  
Wide Range ◽  
Before And After ◽  
The Mean ◽  
Highly Correlated

Estimates of calf blood flow with venous occlusion plethysmography vary widely between studies, perhaps due to the use of different plethysmographs. Consequently, we compared calf blood flow estimates at rest and during reactive hyperemia in eight healthy subjects (four men and four women) with two commonly used plethysmographs: the mercury-in-silastic (Whitney) strain gauge and Dohn air-filled cuff. To minimize technical variability, flow estimates were compared with a Whitney gauge and a Dohn cuff on opposite calves before and after 10 min of bilateral femoral arterial occlusion. To account for any differences between limbs, a second trial was conducted in which the plethysmographs were switched. Resting flows did not differ between the plethysmographs (P = 0.096), but a trend toward lower values with the Whitney was apparent. Peak flows averaged 37% lower with the Whitney (27.8 +/- 2.8 ml.dl-1.min-1) than with the Dohn plethysmograph (44.4 +/- 2.8 ml.dl-1.min-1; P < 0.05). Peak flow expressed as a multiple above baseline was also lower with the Whitney (10-fold) than with the Dohn plethysmograph (14.5-fold; P = 0.02). Across all flows at rest and during reactive hyperemia, estimates were highly correlated between the plethysmographs in all subjects (r2 = 0.96-0.99). However, the mean slope for the Whitney-Dohn relationship was only 60 +/- 2%, indicating that over a wide range of flows the Whitney gauge estimate was 40% lower than that for the Dohn cuff. These results demonstrate that the same qualitative results can be obtained with either plethysmograph but that absolute flow values will generally be lower with Whitney gauges.

Noninvasive measurement of forearm blood flow and oxygen consumption by near-infrared spectroscopy

1994 ◽  
Vol 76 (3) ◽  
pp. 1388-1393 ◽  
Author(s):  
R. A. De Blasi ◽  
M. Ferrari ◽  
A. Natali ◽  
G. Conti ◽  
A. Mega ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Healthy Subjects ◽  
Near Infrared ◽  
Forearm Blood Flow ◽  
Vascular Occlusion ◽  
Venous Occlusion ◽  
The Subject

We applied near-infrared spectroscopy (NIRS) for the simultaneous measurement of forearm blood flow (FBF) and oxygen consumption (VO2) in the human by inducing a 50-mmHg venous occlusion. Eleven healthy subjects were studied both at rest and after hand exercise during vascular occlusion. FBF was also measured by strain-gauge plethysmography. FBF measured by NIRS was 1.9 +/- 0.8 ml.100 ml-1.min-1 at rest and 8.2 +/- 2.9 ml.100 ml-1.min-1 after hand exercise. These values showed a correlation (r = 0.94) with those obtained by the plethysmography. VO2 values were 4.6 +/- 1.3 microM O2 x 100 ml-1.min-1 at rest and 24.9 +/- 11.2 microM O2 x 100 ml-1.min-1 after hand exercise. The scatter of the FBF and VO2 values showed a good correlation between the two variables (r = 0.93). The results demonstrate that NIRS provides the particular advantage of obtaining the contemporary evaluation of blood flow and VO2, allowing correlation of these two variables by a single maneuver without discomfort for the subject.

scholarly journals Parathyroid Hormone's Acute Effect on Vasodilatory Function

2010 ◽  
Vol 3 ◽  
pp. CMED.S4650 ◽  
Author(s):  
P. Farahnak ◽  
L. Lind ◽  
K. Mattala ◽  
I-L. Nilsson
Keyword(s):  
Cardiovascular Disease ◽  
Blood Flow ◽  
Healthy Subjects ◽  
Forearm Blood Flow ◽  
Acute Effect ◽  
Venous Occlusion ◽  
Arterial Infusion ◽  
Resistance Vessels ◽  
Vasodilatory Function ◽  
Pth Level

Parathyroid hormone (PTH) seems to affect the risk of cardiovascular disease. The aim of the present study was to investigate PTH's acute effect on endothelial vasodilatory function in forearm resistance vessels. Ten healthy subjects underwent forearm venous occlusion plethysmography. We measured forearm blood flow at baseline and at a stable, locally increased PTH level after intra-arterial infusion of metacholine and nitroprusside. The contralateral arm served as a control. Ionized calcium (Ca++) and PTH values were normal in all subjects at baseline (1.26 ± 0.02 mM/L, 3.6 ± 1.2 pM/L). After 30 minutes of PTH infusion, the PTH level increased in the active arm (13.8 ± 4.0 pM/L P < 0.01), while the Ca++ level was unchanged (1.25 ± 0.04; mM/L). Both the PTH and the Ca++ level in the contralateral arm remained unchanged, which indicates no systemic influence. The endothelial-dependent vasodilation was inversely correlated to the Ca++ level at baseline (r = −0.75, P < 0.05) and after PTH infusion (r = −0.68, P < 0.05). The vasodilatory function was not affected during PTH-infusion.

scholarly journals Beta alanine supplementation effects on metabolic contribution and swimming performance

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Matheus Silva Norberto ◽  
Ricardo Augusto Barbieri ◽  
Danilo Rodrigues Bertucci ◽  
Ronaldo Bucken Gobbi ◽  
Eduardo Zapaterra Campos ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Energy Demand ◽  
Swimming Performance ◽  
Controlled Study ◽  
Double Blind ◽  
Repeated Measures Anova ◽  
Beta Alanine ◽  
Before And After ◽  
The Difference ◽  
And Performance

Abstract Background Investigations of β-alanine supplementation shows effects on metabolic (aerobic and anaerobic) participation and performance on swimming by a possible blood acidosis buffering. Considering this background, the objective of the present study was to analyze the effects of β-alanine supplementation on metabolic contribution and performance during 400-m swim. Methods Thirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8 g.day− 1 of β-alanine or placebo. Before and after the supplementation period, the total anaerobic contribution (TAn) and 30-s all-out tethered swimming effort (30TS) were assessed. Anaerobic alactic (AnAl) and lactic energy (AnLa) was assumed as the fast component of excess post-exercise oxygen consumption and net blood lactate accumulation during exercise (∆[La−]), respectively. Aerobic contribution (Aer) was determined by the difference between total energy demand and TAn. In addition to conventional statistical analysis (Repeated measures ANOVA; p > 0.05), a Bayesian repeated measures ANOVA was used to evidence the effect probability (BFincl). Results No differences and effects were found between groups, indicating no supplementation effects. Repeated measures ANOVA, with confirmation of effect, was indicate reduce in ∆Lactate (p: 0.001; BFincl: 25.02); absolute AnLa (p: 0.002; BFincl: 12.61), fatigue index (p > 0.001; BFincl: 63.25) and total anaerobic participation (p: 0.008; BFincl: 4.89). Conclusions Thus, the results demonstrated that all changes presented were evidenced as a result of exposure to the training period and β-alanine supplementation doesn’t affect metabolic contribution and performance during 400-m freestyle.

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