Forearm Vasoreactivity in Type I Diabetic Subjects

2001 ◽  
Vol 26 (1) ◽  
pp. 34-43 ◽  
Author(s):  
Jason D. Allen ◽  
Michael Welsch ◽  
Nikki Aucoin ◽  
Robert Wood ◽  
Matt Lee ◽  
...  
Keyword(s):  
Risk Factors ◽  
Blood Flow ◽  
Vascular Function ◽  
Forearm Blood Flow ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Type I ◽  
Handgrip Exercise ◽  
Blood Flows

This study compared forearm vasoreactivity in 15 Type 1 diabetic subjects with 15 healthy controls. The groups were matched for age, exercise capacity, and the absence of other cardiovascular risk factors. Vasoreactivity was measured using strain gauge plethysmography, at rest, after arterial occlusion (OCC), and following OCC coupled with handgrip exercise (ROCC). Forearm blood flows were significantly elevated between conditions 2.58 ± 0.37 ml/100mltissue at rest to 26.80 ± 6.56 after OCC and 32.80 ± 8.26ml/100mltissue following ROCC in Type 1 diabetic subjects. There were no differences in forearm blood flow between groups for any of the conditions. These data indicate the degree of forearm blood flow is directly related to the intensity of the vasodilatory stimulus. However, our study did not reveal evidence of impaired vasodilatory capacity in Type 1 diabetic subjects compared to controls in the absence of other risk factors. Key words: IDDM, vascular function, exercise, fitness, and reactive hyperemia

Gastric mucosal blood flow measured by laser-Doppler velocimetry

1985 ◽  
Vol 249 (4) ◽  
pp. G539-G545 ◽  
Author(s):  
J. W. Kiel ◽  
G. L. Riedel ◽  
G. R. DiResta ◽  
A. P. Shepherd
Keyword(s):  
Blood Flow ◽  
Laser Doppler Velocimetry ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Mucosal Blood Flow ◽  
Gastric Mucosal Blood Flow ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Blood Flows ◽  
Ldv Measurement

To determine the feasibility of measuring gastric mucosal blood flow by laser-Doppler velocimetry (LDV), we utilized two LDV flowmeters to monitor blood flow in mucosa and serosa of chambered canine stomach. In isolated, nonautoregulating gastric segments vasodilated with isoproterenol, LDV mucosal and muscularis blood flows were both linearly related to total electromagnetic blood flow during step increases in perfusion pressure. To assess the depth of the LDV measurement, we recorded reactive hyperemia following arterial occlusion. Reactive hyperemia was frequently registered in the mucosa but rarely in muscularis. Placing a layer of nonperfused mucosa-submucosa between the probe and the perfused mucosa abolished the resting LDV mucosal flow signal and attenuated the recording of peak hyperemia by 85%. Furthermore, intra-arterial infusions of both adenosine and isoproterenol frequently increased LDV mucosal flow and decreased LDV muscularis flow, although total flow was consistently increased. These findings indicate that our LDV instruments yield linear, superficial measurements of gastric blood flow in either mucosa or muscularis. Although calibration in absolute units remains to be achieved, our results demonstrate that LDV is a practical means of studying the gastric mucosal microcirculation.

scholarly journals Hyperglycemia Increases Muscle Blood Flow and Alters Endothelial Function in Adolescents with Type 1 Diabetes

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Amanda S. Dye ◽  
Hong Huang ◽  
John A. Bauer ◽  
Robert P. Hoffman
Keyword(s):  
Blood Flow ◽  
Type 1 Diabetes ◽  
Endothelial Function ◽  
Vascular Function ◽  
Microvascular Complications ◽  
Muscle Blood Flow ◽  
Arterial Occlusion ◽  
Venous Occlusion ◽  
Before And After

Alterations of blood flow and endothelial function precede development of complications in type 1 diabetes. The effects of hyperglycemia on vascular function in early type 1 diabetes are poorly understood. To investigate the effect of hyperglycemia on forearm vascular resistance (FVR) and endothelial function in adolescents with type 1 diabetes, FVR was measured before and after 5 minutes of upper arm arterial occlusion using venous occlusion plethysmography in (1) fasted state, (2) euglycemic state (~90 mg/dL; using 40 mU/m2/min insulin infusion), and (3) hyperglycemic state (~200 mg/dL) in 11 adolescents with type 1 diabetes. Endothelial function was assessed by the change in FVR following occlusion. Seven subjects returned for a repeat study with hyperglycemia replaced by euglycemia. Preocclusion FVR decreased from euglycemia to hyperglycemia (P=0.003). Postocclusion fall in FVR during hyperglycemia was less than during euglycemia (P=0.002). These findings were not reproduced when hyperglycemia was replaced with a second euglycemia. These results demonstrate that acute hyperglycemia causes vasodilation and alters endothelial function in adolescents with type 1 diabetes. In addition they have implications for future studies of endothelial function in type 1 diabetes and provide insight into the etiology of macrovascular and microvascular complications of type 1 diabetes.

Enhanced maximal metabolic vasodilatation in the dominant forearms of tennis players

1986 ◽  
Vol 61 (2) ◽  
pp. 673-678 ◽  
Author(s):  
L. I. Sinoway ◽  
T. I. Musch ◽  
J. R. Minotti ◽  
R. Zelis
Keyword(s):  
Blood Flow ◽  
Forearm Blood Flow ◽  
Arterial Occlusion ◽  
Study Groups ◽  
Venous Occlusion ◽  
Control Group ◽  
Tennis Players ◽  
Blood Flows ◽  
Metabolic Vasodilation ◽  
Adaptation To Exercise

In an effort to evaluate potential peripheral adaptations to training, maximal metabolic vasodilation was studied in the dominant and nondominant forearms of six tennis players and six control subjects. Maximal metabolic vasodilation was defined as the peak forearm blood flow measured after release of arterial occlusion, the reactive hyperemic blood flow (RHBF). Two ischemic stimuli were employed in each subject: 5 min of arterial occlusion (RHBF5) and 5 min of arterial occlusion coupled with 1 min of ischemic exercise (RHBF5ex). RHBF and resting forearm blood flows were measured using venous occlusion strain-gauge plethysmography (ml X min-1 X 100 ml-1). Resting forearm blood flows were similar in both arms of both groups. RHBF5ex was similar in both arms of our control group (dominant, 40.8 +/- 1.2 vs. nondominant, 40.9 +/- 2.1). However, RHBF5ex was 42% higher in the dominant than in the nondominant forearms of our tennis player population (dominant, 48.7 +/- 4.0 vs. nondominant, 34.4 +/- 3.4; P less than 0.05). This intraindividual difference in peak forearm blood flows was not secondary to improved systemic conditioning since the maximal O2 consumptions in the two study groups were similar (controls, 45.4 +/- 3.9 vs. tennis players, 46.1 +/- 1.7). These findings suggest a primary peripheral cardiovascular adaptation to exercise training in the dominant forearms of the tennis players resulting in a greater maximal vasodilatation.

scholarly journals Confocal Blood Flow Videomicroscopy of Thrombus Formation over Human Arteries and Local Targeting of P2X7

2021 ◽  
Vol 22 (8) ◽  
pp. 4066
Author(s):  
Patrizia Marchese ◽  
Maria Lombardi ◽  
Maria Elena Mantione ◽  
Domenico Baccellieri ◽  
David Ferrara ◽  
...  
Keyword(s):  
Blood Flow ◽  
Vascular Function ◽  
Collagen Type ◽  
Thrombus Formation ◽  
Collagen Type I ◽  
Type I ◽  
Prevention Therapy ◽  
Healthy Donors ◽  
Internal Mammary ◽  
Human Arteries

Atherothrombosis exposes vascular components to blood. Currently, new antithrombotic therapies are emerging. Herein we investigated thrombogenesis of human arteries with/without atherosclerosis, and the interaction of coagulation and vascular components, we and explored the anti-thrombogenic efficacy of blockade of the P2X purinoceptor 7 (P2X7). A confocal blood flow videomicroscopy system was performed on cryosections of internal mammary artery (IMA) or carotid plaque (CPL) determining/localizing platelets and fibrin. Blood from healthy donors elicited thrombi over arterial layers. Confocal microscopy associated thrombus with tissue presence of collagen type I, laminin, fibrin(ogen) and tissue factor (TF). The addition of antibodies blocking TF (aTF) or factor XI (aFXI) to blood significantly reduced fibrin deposition, variable platelet aggregation and aTF + aFXI almost abolished thrombus formation, showing synergy between coagulation pathways. A scarce effect of aTF over sub-endothelial regions, more abundant in tissue TF and bundles of laminin and collagen type I than deep intima, may suggest tissue thrombogenicity as molecular structure-related. Consistently with TF-related vascular function and expression of P2X7, the sections from CPL but not IMA tissue cultures pre-treated with the P2X7 antagonist A740003 demonstrated poor thrombogenesis in flow experiments. These data hint to local targeting studies on P2X7 modulation for atherothrombosis prevention/therapy.

Vasodilation contributes to the rapid hyperemia with rhythmic contractions in humans

1998 ◽  
Vol 76 (4) ◽  
pp. 418-427 ◽  
Author(s):  
J K Shoemaker ◽  
M E Tschakovsky ◽  
R L Hughson
Keyword(s):  
Blood Flow ◽  
Forearm Blood Flow ◽  
Perfusion Pressure ◽  
Blood Velocity ◽  
Pulsed Doppler ◽  
Contraction Rate ◽  
Handgrip Exercise ◽  
Arterial Diameter ◽  
Exercise Tests ◽  
Rhythmic Contractions

The hypothesis that the rapid increases in blood flow at the exercise onsetare exclusively due to the mechanical effects of the muscle pump was tested in six volunteersduring dynamic handgrip exercise. While supine, each subject completed a series of eightdifferent exercise tests in which brachial artery blood pressure (BP) was altered by25–30 mmHg (1 mmHg = 133.3 Pa) by positioning the arm above or below the heart.Two different weights, corresponding to 4.9 and 9.7% of maximal voluntary isometriccontraction, were raised and lowered at two different contraction rate schedules (1s:1s and 2s:2swork–rest) each with a 50% duty cycle. Beat-by-beat measures of mean blood velocity (MBV)(pulsed Doppler) were obtained at rest and for 5 min following step increases in work ratewith emphasis on the first 24 s. MBV was increased 50–100% above rest following the firstcontraction in both arm positions (p < 0.05). The increase in MBV from rest was greaterin the below position compared with above, and this effect was observed following the first andsubsequent contractions (p < 0.05). However, the positional effect on the increase inMBV could not be explained entirely by the ~40% greater BP in this position. Also, the greaterworkload resulted in greater increases in MBV as early as the first contraction, compared withthe light workload (p < 0.05) despite similar reductions in forearm volume followingsingle contractions. MBV was greater with faster contraction rate tests by 8 s of exercise. Itwas concluded that microvascular vasodilation must act in concert with a reduction in venouspressure to increase forearm blood flow within the initial 2–4 s of exercise.Key words: Doppler, mean blood velocity, arterial diameter,handgrip exercise, perfusion pressure.

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.

Maximal vascular leg conductance in trained and untrained men

1987 ◽  
Vol 62 (2) ◽  
pp. 606-610 ◽  
Author(s):  
P. G. Snell ◽  
W. H. Martin ◽  
J. C. Buckey ◽  
C. G. Blomqvist
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Reactive Hyperemia ◽  
Venous Occlusion ◽  
Vascular Conductance ◽  
Blood Flows ◽  
Arterial Blood ◽  
Sedentary Subjects

Lower leg blood flow and vascular conductance were studied and related to maximal oxygen uptake in 15 sedentary men (28.5 +/- 1.2 yr, mean +/- SE) and 11 endurance-trained men (30.5 +/- 2.0 yr). Blood flows were obtained at rest and during reactive hyperemia produced by ischemic exercise to fatigue. Vascular conductance was computed from blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. Resting blood flow and mean arterial pressure were similar in both groups (combined mean, 3.0 ml X min-1 X 100 ml-1 and 88.2 mmHg). After ischemic exercise, blood flows were 29- and 19-fold higher (P less than 0.001) than rest in trained (83.3 +/- 3.8 ml X min-1 X 100 ml-1) and sedentary subjects (61.5 +/- 2.3 ml X min-1 X 100 ml-1), respectively. Blood pressure and heart rate were only slightly elevated in both groups. Maximal vascular conductance was significantly higher (P less than 0.001) in the trained compared with the sedentary subjects. The correlation coefficients for maximal oxygen uptake vs. vascular conductance were 0.81 (trained) and 0.45 (sedentary). These data suggest that physical training increases the capacity for vasodilation in active limbs and also enables the trained individual to utilize a larger fraction of maximal vascular conductance than the sedentary subject.

scholarly journals Hepatorenal Syndrome

2021 ◽  
Author(s):  
Arshpal Gill ◽  
Ra’ed Nassar ◽  
Ruby Sangha ◽  
Mohammed Abureesh ◽  
Dhineshreddy Gurala ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Renal Failure ◽  
Blood Flow ◽  
Mortality Rate ◽  
Kidney Injury ◽  
Type I ◽  
Tubular Necrosis ◽  
Cirrhotic Patients

Hepatorenal Syndrome (HRS) is an important condition for clinicians to be aware of in the presence of cirrhosis. In simple terms, HRS is defined as a relative rise in creatinine and relative drop in serum glomerular filtration rate (GFR) alongside renal plasma flow (RPF) in the absence of other competing etiologies of acute kidney injury (AKI) in patients with hepatic cirrhosis. It represents the end stage complication of decompensated cirrhosis in the presence of severe portal hypertension, in the absence of prerenal azotemia, acute tubular necrosis or others. It is a diagnosis of exclusion. The recognition of HRS is of paramount importance for clinicians as it carries a high mortality rate and is an indication for transplantation. Recent advances in understanding the pathophysiology of the disease improved treatment approaches, but the overall prognosis remains poor, with Type I HRS having an average survival under 2 weeks. Generally speaking, AKI and renal failure in cirrhotic patients carry a very high mortality rate, with up to 60% mortality rate for patients with renal failure and cirrhosis and 86.6% of overall mortality rates of patients admitted to the intensive care unit. Of the various etiologies of renal failure in cirrhosis, HRS carries a poor prognosis among cirrhotic patients with acute kidney injury. HRS continues to pose a diagnostic challenge. AKI can be either pre-renal, intrarenal or postrenal. Prerenal causes include hypovolemia, infection, use of vasodilators and functional due to decreased blood flow to the kidney, intra-renal such as glomerulopathy, acute tubular necrosis and post-renal such as obstruction. Patients with cirrhosis are susceptible to developing renal impairment. HRS may be classified as Type 1 or rapidly progressive disease, and Type 2 or slowly progressive disease. There are other types of HRS, but this chapter will focus on Type 1 HRS and Type 2 HRS. HRS is considered a functional etiology of acute kidney injury as there is an apparent lack of nephrological parenchymal damage. It is one several possibilities for acute kidney injury in patients with both acute and chronic liver disease. Acute kidney injury (AKI) is one of the most severe complications that could occur with cirrhosis. Up to 50% of hospitalized patients with cirrhosis can suffer from acute kidney injury, and as mentioned earlier an AKI in the presence of cirrhosis in a hospitalized patient has been associated with nearly a 3.5-fold increase in mortality. The definition of HRS will be discussed in this chapter, but it is characterized specifically as a form of acute kidney injury that occurs in patients with advanced liver cirrhosis which results in a reduction in renal blood flow, unresponsive to fluids this occurs in the setting of portal hypertension and splanchnic vasodilation. This chapter will discuss the incidence of HRS, recognizing HRS, focusing mainly on HRS Type I and Type II, recognizing competing etiologies of renal impairment in cirrhotic patients, and the management HRS.

Differences in reactive hyperemia between the intestinal mucosa and muscularis

1984 ◽  
Vol 247 (6) ◽  
pp. G617-G622
Author(s):  
A. P. Shepherd ◽  
G. L. Riedel
Keyword(s):  
Blood Flow ◽  
Metabolic Rate ◽  
Laser Doppler Velocimetry ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Oxygen Demand ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Total Blood ◽  
Total Blood Flow

In a previous study of regional intestinal blood flow by laser-Doppler velocimetry, we noted that the mucosa displayed reactive hyperemia following arterial occlusion but that the muscularis did not. Therefore, to determine whether this observation is generally valid, we compared responses of the mucosa and muscularis externa to arterial occlusion. We measured total blood flow to isolated loops of canine small bowel with an electromagnetic flow probe on the supply artery; blood flow either in the mucosa or in the muscularis was measured by laser-Doppler velocimetry. Mucosal and total blood flow consistently showed reactive hyperemia in response to a 60-s occlusion, but the muscularis did not. To determine whether metabolic rate influenced reactive hyperemia, we increased enteric oxygen uptake by placing 5% bile and transportable solutes in the lumen; these agents increased oxygen consumption by 36%. After a 60-s occlusion, the durations of both total and mucosal reactive hyperemia were significantly prolonged by increased metabolic rate. Similarly, the payback-to-debt ratios in both total and mucosal blood flows were significantly increased at elevated metabolic rate. These data support the conclusions that reactive hyperemia occurs more frequently and has a greater magnitude in the mucosa compared with the muscularis and both total and mucosal reactive hyperemia are strongly influenced by the preocclusive oxygen demand. These findings therefore constitute further evidence that metabolic factors contribute to reactive hyperemia in the intestinal circulation.

Sign in / Sign up

Export Citation Format

Share Document