Affect Blood Flow Research Articles

Pathophysiology of the cortico-sympathoadrenal system in the postoperative period of partial nephrectomy

Introduction. Organ-preserving kidney surgeries are widespread in urological practice. Any surgical intervention triggers a cascade of reactions in the body that are characteristic of stressful situations, which adversely affects blood flow volume in the parenchymal organs, worsens microcirculation, and reduces the trophic and reparative abilities of organs. The application of anti-ischemic protection is an essential part of patient rehabilitation to maintain renal function. Objective. To investigate the nephroprotective properties of α-tocopherol acetate (a-TA) and its effect on α-tocopherol acetate (a-TA) parameters of the cortico-sympathoadrenal system following organ-preserving kidney surgery. Material and methods. An experimental study was performed on 70 white laboratory rats, 10 of which were not subjected to surgical treatment. Sixty rats underwent lower pole left kidney superimposition with Z-joints. Postoperatively, 30 rats were intramuscularly injected with a 10% oil solution of 0.2 mL a-TA twice a day for 5 days. The cortico-sympathoadrenal system parameters were determined on the 7th, 14th, and 28th days. Results. Postoperative administration of a-TA resulted in early normalization of the cortico-sympathoadrenal system. Conclusion. The studied indices regarding the tissue of the operated kidney are responsible for regulating vascular tone, severity of the inflammatory response, microcirculation, and reparative processes. The use of a-TA accelerates recovery from organ-preserving surgery and biochemical abnormalities. (For citation: Shormanov IS, Los MS. Pathophysiology of the cortico-sympathoadrenal system in the postoperative period of partial nephrectomy. Urologicheskie vedomosti. 2018;8(2):11-17. doi: 10.17816/uroved8211-17).

Recombinant human erythropoietin does not affect several microvascular parameters in well-trained cyclists.

Recombinant human erythropoietin (rHuEPO) has been used as a performance‐enhancing agent by athletes in a variety of sports. The resulting increase in hematocrit levels leads to increased blood viscosity and can affect blood flow, potentially increasing the athlete's risk of developing health complications. However, the actual effects of using rHuEPO on microvascular blood flow and post‐occlusive reactive hyperemia are currently unknown. We therefore evaluated the effect of rHuEPO on the cutaneous microcirculation in well‐trained cyclists using laser speckle contrast imaging (LSCI). This study was part of a randomized, double‐blind, placebo‐controlled, parallel trial designed to investigate the effects of rHuEPO in 47 well‐trained adult cyclists (age 18–50 years). Subjects received a weekly dose of either rHuEPO or placebo for 8 weeks, and LSCI was performed at baseline, after a maximal exercise test in week 6, and before maximal exercise in week 8. Endpoints included basal blood flux, maximum post‐occlusion reperfusion, and time to return to baseline. Despite an increase in hematocrit levels in the rHuEPO‐treated group, we found no statistically significant difference in microvascular function measured between the rHuEPO‐treated group and the placebo group. Our results suggest that the increased hematocrit levels in rHuEPO‐treated well‐trained cyclists are not associated with changes in microvascular blood flow or post‐occlusive reactive hyperemia measured using LSCI.

Altered Placental Chorionic Arterial Biomechanical Properties During Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is a pregnancy complication due to placental dysfunction that prevents the fetus from obtaining enough oxygen and nutrients, leading to serious mortality and morbidity risks. There is no treatment for IUGR despite having a prevalence of 3% in developed countries, giving rise to an urgency to improve our understanding of the disease. Applying biomechanics investigation on IUGR placental tissues can give important new insights. We performed pressure-diameter mechanical testing of placental chorionic arteries and found that in severe IUGR cases (RI > 90th centile) but not in IUGR cases (RI < 90th centile), vascular distensibility was significantly increased from normal. Constitutive modeling demonstrated that a simplified Fung-type hyperelastic model was able to describe the mechanical properties well, and histology showed that severe IUGR had the lowest collagen to elastin ratio. To demonstrate that the increased distensibility in the severe IUGR group was related to their elevated umbilical resistance and pulsatility indices, we modelled the placental circulation using a Windkessel model, and demonstrated that vascular compliance (and not just vascular resistance) directly affected blood flow pulsatility, suggesting that it is an important parameter for the disease. Our study showed that biomechanics study on placenta could extend our understanding on placenta physiology.

Is intra-abdominal hypertension a risk factor for ventilator-associated pneumonia?

In the last years, there has been a significant amount of research about the impact of intra-abdominal hypertension (IAH) on the outcomes of critical care patients. IAH is increasingly recognized as potential complication in intensive care unit (ICU) patients. IAH affects all body systems, most notably the cardiac, respiratory, renal, and neurologic systems. IAH affects blood flow to various organs and plays a significant role in the prognosis of the patients. Recognition of IAH, its risk factors and clinical signs can reduce the morbidity and mortality associated. Moreover, knowledge of the pathophysiology may help rationalize the therapeutic approach. On the other hand, ICU patients present frequently ventilator- associated respiratory infections. Ventilator-associated pneumonia (VAP) is the most common healthcare-associated infection (HAI) in adult critical care units. It is associated with increased ICU stay, patient ventilator days and mortality. This paper reviews the relationship between IAH and VAP. Despite animal experimentation and physiological studies on humans, in favor of the impact of IAH to VAP, there is no definitive clinical data that IAH is associated with VAP. Microaspirations form the gastrointestinal track is a pathophysiological mechanism for VAP. This review provides data suggesting that under IAH conditions bacterial translocation might be an additional responsible mechanism for VAP in those patients that merits further investigation in the future.

The effect of respiration-driven flow waveforms on hemodynamic metrics used in Fontan surgical planning

ObjectivePoor total cavopulmonary connection (TCPC) hemodynamics have been hypothesized to be associated with long-term complications in Fontan patients. Image-based Fontan surgical planning has shown great potential as a clinical tool because it can pre-operatively evaluate patient-specific hemodynamics. Current surgical planning paradigms commonly utilize cardiac-gated phase contrast magnetic resonance (MR) imaging to acquire vessel flows. These acquisitions are often taken under breath-held (BH) conditions and ignore the effect of respiration on blood flow waveforms. This study investigates the effect of respiration-driven flow waveforms on patient-specific hemodynamics using real-time MR acquisitions. MethodsPatient-specific TCPCs were reconstructed from cardiovascular MR images. Real-time phase contrast MR images were acquired under both free-breathing (FB) and breath-held conditions for 9 patients. Numerical simulations were employed to assess flow structures and hemodynamics used in Fontan surgical planning including hepatic flow distribution (HFD) and indexed power loss (iPL), which were then compared between FB and BH conditions. ResultsDifferences in TCPC flow structures between FB and BH conditions were observed throughout the respiratory cycle. However, the average differences (BH – FB values for each patient, which are then averaged) in iPL and HFD between these conditions were 0.002 ± 0.011 (p = 0.40) and 1 ± 3% (p = 0.28), respectively, indicating no significant difference in clinically important hemodynamic metrics. ConclusionsRespiration affects blood flow waveforms and flow structures, but might not significantly influence the values of iPL or HFD. Therefore, breath-held MR acquisition can be adequate for Fontan surgical planning when focusing on iPL and HFD.

Reader response: Peak perihemorrhagic edema correlates with functional outcome in intracerebral hemorrhage.

We read with interest the study by Volbers et al.,1 who found that perihemorrhagic edema (PHE) independently predicted functional outcome after acute intracerebral hemorrhage (ICH) and was associated with inflammatory markers and hematoma expansion. Cerebral edema formation has a multifactorial etiology with time-dependent contributing factors like increased hydrostatic pressure, transcapillary efflux of electrolytes and fluids, clot retraction, thrombin production, inflammatory activation, erythrocyte lysis, iron deposition, and hemoglobin-induced neurotoxicity. Sudden blood pressure (BP) increases may promote arterial bleeding and hematoma growth; BP rises and falls may contribute to disruption of the blood–brain barrier and enhance vasogenic edema. Excessive BP fluctuations may lead to further cell injury and amplify the secondary brain damage by affecting blood flow and brain perfusion in the area of impaired cerebral autoregulation surrounding the hematoma.

Quantification of near-wall hemodynamic risk factors in large-scale cerebral arterial trees.

Detailed hemodynamic analysis of blood flow in pathological segments close to aneurysm and stenosis has provided physicians with invaluable information about the local flow patterns leading to vascular disease. However, these diseases have both local and global effects on the circulation of the blood within the cerebral tree. The aim of this paper is to demonstrate the importance of extending subject-specific hemodynamic simulations to the entire cerebral arterial tree with hundreds of bifurcations and vessels, as well as evaluate hemodynamic risk factors and waveform shape characteristics throughout the cerebral arterial trees. Angioarchitecture and in vivo blood flow measurement were acquired from healthy subjects and in cases with symptomatic intracranial aneurysm and stenosis. A global map of cerebral arterial blood flow distribution revealed regions of low to high hemodynamic risk that may significantly contribute to the development of intracranial aneurysms or atherosclerosis. Comparison of pre-intervention and post-intervention of pathological cases further shows large angular phase shift (~33.8°), and an augmentation of the peak-diastolic velocity. Hemodynamic indexes of waveform analysis revealed on average a 16.35% reduction in the pulsatility index after treatment from lesion site to downstream distal vessels. The lesion regions not only affect blood flow streamlines of the proximal sites but also generate pulse wave shift and disturbed flow in downstream vessels. This network effect necessitates the use of large-scale simulation to visualize both local and global effects of pathological lesions.

Sex‐specific Conditions Affecting Vascular Tone, Cerebral Blood Flow and Cognition

There are sex and sex‐hormone specific differences in autonomic nervous system control of blood pressure. The sympathetic nerve fibers of the autonomic nervous system innervate skeletal muscle blood vessels, initiating vasoconstriction, and thus regulate blood flow and vascular tone. This regulation of vascular tone is different between men and women, such that estrogen increases the activity of the b2‐adrenergic receptor activity (causing vasodilation) which offset sympathetically‐mediated vasoconstriction and results in lower blood pressure values in young women. Higher sympathetic nerve activity is associated with greater augmented aortic blood pressure in young men, but lower augmented aortic blood pressure in young women. Such differences in blood pressure regulation will likely have effects that extend beyond blood pressure, affecting blood flow, and ultimately tissue structure and function. For example, higher aortic blood pressure and greater arterial stiffness of the central arteries are associated with white matter hyperintensity fraction in normotensive postmenopausal women and older adults. In addition, there are conditions unique to women, menopause and pregnancy, that further affect blood pressure and blood flow regulation. Pregnancy constitutes a stress that challenges the regulation of blood pressure and blood flow in women. Hypertensive conditions of pregnancy, such as preeclampsia, carry life‐long risk for developing cardiovascular and cerebrovascular diseases. We evaluated the influence of pregnancy history in postmenopausal women on vascular function, cerebral blood flow, and cognition 35 years after pregnancy. Aortic blood pressure was associated with lower cognitive function scores in women with a history of preeclampsia. Additionally, women with a history of preeclampsia had lower cerebral blood flow responses to a vasodilatory stimulus and this was associated with greater intravascular cellular activation. Furthermore, women with a history of preeclampsia and with late‐life hypertension had atrophy in specific regions of the brain, suggesting that pregnancy history may later impact brain structure. Therefore, conditions that a woman may experience during pregnancy may be informative for future risk of disease. In summary, understanding sex‐specific physiological mechanisms, and how this may change over the lifespan is crucial for identification and treatment of individuals at accelerated risk of cardiovascular and cerebrovascular disease.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Validation of diffuse correlation spectroscopy sensitivity to nicotinamide-induced blood flow elevation in the murine hindlimb using the fluorescent microsphere technique.

Nicotinamide has been shown to affect blood flow in both tumor and normal tissues, including skeletal muscle. Intraperitoneal injection of nicotinamide was used as a simple intervention to test the sensitivity of noninvasive diffuse correlation spectroscopy (DCS) to changes in blood flow in the murine left quadriceps femoris skeletal muscle. DCS was then compared with the gold-standard fluorescent microsphere (FM) technique for validation. The nicotinamide dose-response experiment showed that relative blood flow measured by DCS increased following treatment with 500- and 1000-mg / kg nicotinamide. The DCS and FM technique comparison showed that blood flow index measured by DCS was correlated with FM counts quantified by image analysis. The results of this study show that DCS is sensitive to nicotinamide-induced blood flow elevation in the murine left quadriceps femoris. Additionally, the results of the comparison were consistent with similar studies in higher-order animal models, suggesting that mouse models can be effectively employed to investigate the utility of DCS for various blood flow measurement applications.

Roasted Barley Extract Affects Blood Flow in the Rat Tail and Increases Cutaneous Blood Flow and Skin Temperature in Humans.

Roasted barley extract (RBE, "Mugicha") is a traditional Japanese beverage reported to improve blood viscosity and affect food functionality. RBE is suggested to contain 2,5-diketopiperazines, which are the functional component with neuroprotective and immunostimulatory effects that are produced in food through roasting. In this study, we investigated the effects of RBE on blood circulation, both clinically and in rats. At first, we confirmed five 2,5-diketopiperazine derivatives in RBE by LC-MS analysis. Secondarily, we revealed that RBE affects blood flow in the rat tail and compared the efficacy on rat tail blood flow among five 2,5-diketopiperazines in RBE. Especially, cyclo(d-Phe-l-Pro) was the most effective in increasing blood flow in the rat tail. We also researched the mechanism of cyclo(d-Phe-l-Pro) with rat aorta study. As a result, we confirmed that cyclo(d-Phe-l-Pro) has an effect on vasodilatation through the release of nitric oxide in the vascular endothelium. Finally, we also confirmed that RBE affects cutaneous blood flow and increases skin temperature in humans.

Multiscale modelling of blood flow in cerebral microcirculation: Details at capillary scale control accuracy at the level of the cortex.

Aging or cerebral diseases may induce architectural modifications in human brain microvascular networks, such as capillary rarefaction. Such modifications limit blood and oxygen supply to the cortex, possibly resulting in energy failure and neuronal death. Modelling is key in understanding how these architectural modifications affect blood flow and mass transfers in such complex networks. However, the huge number of vessels in the human brain—tens of billions—prevents any modelling approach with an explicit architectural representation down to the scale of the capillaries. Here, we introduce a hybrid approach to model blood flow at larger scale in the brain microcirculation, based on its multiscale architecture. The capillary bed, which is a space-filling network, is treated as a porous medium and modelled using a homogenized continuum approach. The larger arteriolar and venular trees, which cannot be homogenized because of their fractal-like nature, are treated as a network of interconnected tubes with a detailed representation of their spatial organization. The main contribution of this work is to devise a proper coupling model at the interface between these two components. This model is based on analytical approximations of the pressure field that capture the strong pressure gradients building up in the capillaries connected to arterioles or venules. We evaluate the accuracy of this model for both very simple architectures with one arteriole and/or one venule and for more complex ones, with anatomically realistic tree-like vessels displaying a large number of coupling sites. We show that the hybrid model is very accurate in describing blood flow at large scales and further yields a significant computational gain by comparison with a classical network approach. It is therefore an important step towards large scale simulations of cerebral blood flow and lays the groundwork for introducing additional levels of complexity in the future.

Development of a Computational Fluid Dynamics Model for Myocardial Bridging

Introduction: Myocardial bridging (MB) is a congenital heart abnormality where a coronary artery tunnels into the myocardium and is repetitively squeezed during systole. Myocardial bridging adversely affects blood flow haemodynamics and contributes to development of atherosclerotic plaque in proximal arterial segments. This study aimed to analyse the relationship between MB characteristics, shear stress, and flow deviations, using computational modelling and patient-specific physiology measurements.

High-speed on-demand 3D printed bioresorbable vascular scaffolds

Recent development of the high-resolution Micro-Continuous Liquid Interface Production (μCLIP) process has enabled 3D printing of biomedical devices with micron-scale precision. Despite our recent success in demonstrating fabrication of bioresorbable vascular scaffolds (BVS) via μCLIP, key technical obstacles remain. Specifically, achieving comparable radial stiffness to nitinol stents required strut thickness of 400 μm. Such large struts would negatively affect blood flow through smaller coronary vessels. Low printing speed also made the process impractical for potential on-demand fabrication of patient-specific BVSs. Lack of a systematic optimization strategy capturing the sophisticated process-materials-performance dependencies impedes development of on-demand fabrication of BVSs and other biomedical devices. Herein, we developed a systematic method to optimize the entangled process parameters, such as materials strength/stiffness, exposure dosage, and fabrication speed. A dedicated speed working curve method was developed to calibrate the μCLIP process, which allowed experimental determination of dimensionally-accurate fabrication parameters. Composition of the citric acid-based bioresorbable ink (B-Ink™) was optimized to maximize BVS radial stiffness, allowing scaffold struts at clinically-relevant sizes. Through the described dual optimization, we have successfully fabricated BVSs with radial stiffness comparable to nitinol stents and strut thickness of 150 μm, which is comparable to the ABSORB GT1BVS. Fabrication of 2-cm long BVS with 5 μm, 10 μm, and 15 μm layer slicing can now be accomplished within 26.5, 15.3, and 11.3 min, respectively. The reported process optimization methods and high-speed, high-resolution 3D printing capability demonstrate a promising solution for on-demand fabrication of patient-specific biomedical devices.

Interleukin-12 and its procoagulant effect on erythrocytes, platelets and fibrin(ogen): the lesser known side of inflammation.

Inflammation, with its associated inflammatory molecules, is integral to most chronic diseases, including the various cardiovascular diseases. Interleukin 12 (IL12) is one of the inflammatory cytokines that is upregulated during inflammation; however, we know very little about its exact effect on red blood cells (RBCs), platelets and fibrin(ogen). IL12 is an important pleiotropic cytokine in early inflammatory responses and has potent immunomodulatory, antitumour and anti-infection activity. Here we investigate how low levels of circulating IL12, comparable to levels found during chronic inflammation, affect coagulation parameters, platelets and RBCs. We used thromboelastography, scanning electron microscopy, refractometery and wide-field microscopy. Our results show that IL12 caused hypercoagulation, platelet activation and spreading, as well as RBC agglutination. This phenomenon has far-reaching implications for treatment of the plethora of conditions where IL12 is upregulated, since it suggests aberrant haemorheology as agglutination affects blood flow. This information might be used in future to target the lowering of IL12 in inflammatory conditions, as well as address RBC agglutination.

Prostate vascular flow: The effect of the ejaculation on the power doppler ultrasonographic examination.

Power Doppler sonography (PD) can accurately depict tissue perfusion, recognize slow flows, and is relatively angle independent. The monitoring of local blood flow by Doppler ultrasonography is helpful in differentiating prostatic physio-pathological conditions, but the recognizing of physiological variables that could affect it is crucial to apply this technique in clinical practice. This study aimed to evaluate if ejaculation affects blood flow to the prostate and to state how long this effect lasts. Serial PD examinations of prostate were performed in 18 dogs (1-5years, 6-40kg) immediately before (T0) and after (T1) the ejaculation, and repeated 6 (T2), 18 (T3) and 24 (T4) hours later. For each examination, two representative PD images were chosen and ranked by two independent observers according to the following scoring system: 0=mild subcapsular (S) vascularization without clear evidence of parenchymal (P) vascularization; 1=moderate P and S vascularization; 2=severe S and moderate P vascularization; 3=severe P and moderate S vascularization; 4=severe P and S vascularization. Interobserver agreement was assessed using Kappa of Cohen. Ranked data, grouped according to time, were compared by ANOVA and Tukey HSD test (p<.05). Variations in the vascular flow pattern at different times were observed for all dogs. The statistical analysis evidenced a significant difference for T0 vs T1 and vs T2 and vs T3 (p<.01), with no significant difference for T0 vs T4 (p>.05). Interobserver agreement was very good (Kappa of Cohen = 0.86). This study demonstrated a definite increase in vascular flow to the prostate after ejaculation. The present results suggest a minimum of 24hr sexual rest before the PD examination of the gland. This result should be taken into account whenever Doppler sonography is used to evaluate potential hyperaemia in dogs suspected of having prostate abnormalities.

Sex-specific factors regulating pressure and flow.

What is the topic of this review? There are sex- and sex-hormone-specific differences in autonomic control of blood pressure, central haemodynamics and cerebral blood flow. What advances does it highlight? Sex differences in autonomic control of blood pressure may underlie other sex-specific characteristics associated with cerebral blood flow, which can, in turn, affect tissue function. Over the last decade, there have been many published reports on sex differences in blood pressure regulation between young men and young women. The autonomic nervous system is a primary contributor to both acute and long-term blood pressure regulation. Sex differences in blood pressure regulation are likely to have effects that extend beyond mean arterial pressure and that can affect blood flow and tissue function. This short review includes recent literature from our laboratory focusing on autonomic control of the circulation, specifically age- and sex-hormone-related differences in central haemodynamics and cerebral blood flow, and discusses potential clinical implications.

A Working Module for the Neurovascular Unit in the Sexually Dimorphic Nucleus of the Preoptic Area.

The neurovascular unit (NVU) can be conceptualized as a functional entity consisting of neurons, astrocytes, pericytes, and endothelial and smooth muscle cells that operate in concert to affect blood flow to a very circumscribed area. Although we are currently in a "golden era" of bioengineering, there are, as yet, no living NVUs-on-a-chip modules available and the development of a neural chip that would mimic NVUs is a seemingly lofty goal. The sexually dimorphic nucleus of the preoptic area (SDN-POA) is a tiny brain structure (between 0.001~0.007mm3 in rats) with an assessable biological function (i.e., male sexual behavior). The present effort was undertaken to determine whether there are identifiable NVUs in the SDN-POA by assessing its vasculature relative to its known neural components. First, a thorough and systematic review of thousands of histologic and immunofluorescent images from 201 weanling and adult rats was undertaken to define the characteristics of the vessels supplying the SDN-POA: its primary supply artery/arteriole and capillaries are physically inseparable from their neural elements. A subsequent immunofluorescent study targeting α-smooth muscle actin confirmed the identity of an artery/arteriole supplying the SDN-POA. In reality, the predominant components of the SDN-POA are calbindin D28k-positive neurons that are comingled with tyrosine hydroxylase-positive projections. Finally, a schematic of an SDN-POA NVU is proposed as a working model of the basic building block of the CNS. Such modules could serve the study of neurovascular mechanisms and potentially inform the development of next generation bioengineered neural transplants, i.e., the construct of an NVU neural chip.

Reduced blood flow through intrapulmonary arteriovenous anastomoses during exercise in lowlanders acclimatizing to high altitude.

What is the central question of this study? The aim was to determine, using the technique of agitated saline contrast echocardiography, whether exercise after 4-7days at 5050m would affect blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) compared with exercise at sea level. What is the main finding and its importance? Despite a significant increase in both cardiac output and pulmonary pressure during exercise at high altitude, there is very little Q̇IPAVA at rest or during exercise after 4-7days of acclimatization. Mathematical modelling suggests that bubble instability at high altitude is an unlikely explanation for the reduced Q̇IPAVA. Blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) is elevated during exercise at sea level (SL) and at rest in acute normobaric hypoxia. After high altitude (HA) acclimatization, resting Q̇IPAVA is similar to that at SL, but it is unknown whether this is true during exercise at HA. We reasoned that exercise at HA (5050m) would exacerbate Q̇IPAVA as a result of heightened pulmonary arterial pressure. Using a supine cycle ergometer, seven healthy adults free from intracardiac shunts underwent an incremental exercise test at SL [25, 50 and 75% of SL peak oxygen consumption (V̇O2 peak )] and at HA (25 and 50% of SL V̇O2 peak ). Echocardiography was used to determine cardiac output (Q̇) and pulmonary artery systolic pressure (PASP), and agitated saline contrast was used to determine Q̇IPAVA (bubble score; 0-5). The principal findings were as follows: (i) Q̇ was similar at SL rest (3.9±0.47lmin-1 ) compared with HA rest (4.5±0.49lmin-1 ; P=0.382), but increased from rest during both SL and HA exercise (P<0.001); (ii) PASP increased from SL rest (19.2±0.7mmHg) to HA rest (33.7±2.8mmHg; P=0.001) and, compared with SL, PASP was further elevated during HA exercise (P=0.003); (iii) Q̇IPAVA was increased from SL rest (0) to HA rest (median=1; P=0.04) and increased from resting values during SL exercise (P<0.05), but was unchanged during HA exercise (P=0.91), despite significant increases in Q̇ and PASP. Theoretical modelling of microbubble dissolution suggests that the lack of Q̇IPAVA in response to exercise at HA is unlikely to be caused by saline contrast instability.

The effect of nitric oxide synthase inhibition with and without inhibition of prostaglandins on blood flow in different human skeletal muscles

Animal studies suggest that the inhibition of nitric oxide synthase (NOS) affects blood flow differently in different skeletal muscles according to their muscle fibre type composition (oxidative vs glycolytic). Quadriceps femoris (QF) muscle consists of four different muscle parts: vastus intermedius (VI), rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) of which VI is located deep within the muscle group and is generally regarded to consist mostly of oxidative muscle fibres. We studied the effect of NOS inhibition on blood flow in these four different muscles by positron emission tomography in eight young healthy men at rest and during one-leg dynamic exercise, with and without combined blockade with prostaglandins. At rest blood flow in the VI (2.6±1.1ml/100g/min) was significantly higher than in VL (1.9±0.6ml/100g/min, p=0.015) and RF (1.7±0.6ml/100g/min, p=0.0015), but comparable to VM (2.4±1.1ml/100g/min). NOS inhibition alone or with prostaglandins reduced blood flow by almost 50% (p<0.001), but decrements were similar in all four muscles (drug×muscle interaction, p=0.43). During exercise blood flow was also the highest in VI (45.4±5.5ml/100g/min) and higher compared to VL (35.0±5.5ml/100g/min), RF (38.4±7.4ml/100g/min), and VM (36.2±6.8ml/100g/min). NOS inhibition alone did not reduce exercise hyperemia (p=0.51), but combined NOS and prostaglandin inhibition reduced blood flow during exercise (p=0.002), similarly in all muscles (drug×muscle interaction, p=0.99). NOS inhibition, with or without prostaglandins inhibition, affects blood flow similarly in different human QF muscles both at rest and during low-to-moderate intensity exercise.

Acute dark chocolate ingestion is beneficial for hemodynamics via enhancement of erythrocyte deformability in healthy humans

Erythrocyte deformability is an important property of erythrocytes that considerably affects blood flow and hemodynamics. The high content of polyphenols present in dark chocolate has been reported to play a protective role in functionality of erythrocytes. We hypothesized that chocolate might influence erythrocytes not only after repeated chronic intake, but also immediately after its ingestion. Thus, we determined the acute effect of dark chocolate and milk (with lower content of biologically active substances) chocolate intake on erythrocyte deformability. We also focused on selected factors that may affect erythrocyte deformability, specifically nitric oxide production in erythrocytes and total antioxidant capacity of plasma. We determined posttreatment changes in the mentioned parameters 2hours after consumption of chocolate compared with their levels before consumption of chocolate. In contrast to milk chocolate intake, the dark chocolate led to a significantly higher increase in erythrocyte deformability. Nitric oxide production in erythrocytes was not changed after dark chocolate intake, but significantly decreased after milk chocolate. The plasma total antioxidant capacity remained unaffected after ingestion of both chocolates. We conclude that our hypothesis was confirmed. Single ingestion of dark chocolate improved erythrocyte deformability despite unchanged nitric oxide production and antioxidant capacity of plasma. Increased deformability of erythrocytes may considerably improve rheological properties of blood and thus hemodynamics in humans, resulting in better tissue oxygenation.