Arteries Of Different Sizes Research Articles

Vascular calcification in different arterial beds in ex vivo ring culture and in vivo rat model

Vascular calcification is a risk factor for cardiovascular and kidney diseases. Medial calcification may differently affect the arterial tree depending on vessel location and smooth muscle injury. The aim was to map the anatomical distribution of vascular calcifications on different arteries and artery locations, in cultured artery rings (ex vivo) and in a rat model of elastocalcinosis (in vivo). Vascular calcification was assessed histologically (von Kossa staining of the media) and by calcium content measurement. Arteries of different sizes were harvested from untreated rats for ring culture and from the vitamin D3-nicotine (VDN) rat model for direct observation. When cultured in pro-calcifying conditions, thoracic aorta exhibited similar calcification from the arch to the diaphragm. Calcification increased in abdominal aorta along with the reduction in cross sectional area. Carotid and renal arteries exhibited similar ex vivo calcification. In VDN rats, calcification was greater in carotid artery than in aorta, and was accompanied by fibrosis and apoptosis. Ex vivo, calcification was increased by the induction of lesions on arteries. Along the vascular tree, calcification of the arterial wall increases with the narrowing of vessels in ex vivo ring culture and in vivo. The observed differences represent local susceptibility of the vessels to the calcifying processes.

ARTERIAL HYPERTENSION IN YOUNG PEOPLE REVEALING SYSTEMIC AFFECTIONS

Objective: Arterial hypertension in young patients can reveal or be a complication involving multiple mechanisms (coarctation of the aorta, inflammatory stenosis and / or thrombosis of the renal artery, vasculitis of arteries of different sizes, glomerular nephropathies, fibrosis retro peritoneal …) many systemic conditions. Design and method: We retrospectively studied hypertension in 16 patients under 40. Data were collected retrospectively from 16 patients, under 40 years old, and hospitalized d in an internal medicine department for systemic diseases. Results: These were 2 men and 14 women. The average age was 34 years and 8 months (range 16–40 years). The systemic conditions identified were: systemic lupus erythematosus (7 cases), Takayasu disease (4 cases), systemic sclerosis (1 case), Sjögren syndrome (1 case), Behçet's disease (1 case), Buerger's disease (1 case) and cryoglobulinemia (1 case). Conclusions: Hypertension in young patients revealing a systemic disorder is rare and has complex mechanisms. Its etiological treatment depends on the specific context of each identified condition, on surgical treatment and / or long-term medical treatment.

An integrated lumped-parameter model of the cardiovascular system for the simulation of acute ischemic stroke: description of instantaneous changes in hemodynamics.

Acute Ischemic Stroke (AIS) is defined as the acute condition of occlusion of a cerebral artery and is often caused by a Hypertensive Condition (HC). Due to its sudden occurrence, AIS is not observable the right moment it occurs, thus information about instantaneous changes in hemodynamics is limited. This study aimed to propose an integrated Lumped Parameter (LP) model of the cardiovascular system to simulate an AIS and describe instantaneous changes in hemodynamics. In the integrated LP model of the cardiovascular system, heart chambers have been modelled with elastance systems with controlled pressure inputs; heart valves have been modelled with static open/closed pressure-controlled valves; eventually, the vasculature has been modelled with resistor-inductor-capacitor (RLC) direct circuits and have been linked to the rest of the system through a series connection. After simulating physiological conditions, HC has been simulated by changing pressure inputs and constant RLC parameters. Then, AIS occurring in arteries of different sizes have been simulated by considering time-dependent RLC parameters due to the elimination from the model of the occluding artery; instantaneous changes in hemodynamics have been evaluated by Systemic Arteriolar Flow (Qa) and Systemic Arteriolar Pressure (Pa) drop with respect to those measured in HC. Occlusion of arteries of different sizes leaded to an average Qa drop of 0.38 ml/s per cardiac cycle (with minimum and maximum values of 0.04 ml/s and 1.93 ml/s) and average Pa drop of 0.39 mmHg, (with minimum and maximum values of 0.04 mmHg and 1.98 mmHg). In conclusion, hemodynamic variations due to AIS are very small with respect to HC. A direct relation between the inverse of the length of the artery in which the occlusion occurs and the hemodynamic variations has been highlighted; this may allow to link the severity of AIS to the length of the interested artery.

Cholesterol Inhibits H2S‐Mediated Vasodilation

Hydrogen sulfide (H2S), the most recently described endothelium‐derived vasodilator, is predominantly produced in the endothelium by cystathionine γ‐lyase (CSE). We previously demonstrated that within endothelial cells (ECs), H2S‐mediated vasodilation involves activation of transient receptor potential cation channel subfamily V member 4 (TRPV4)‐dependent Ca2+ influx and large conductance Ca2+‐activated potassium (BK) channel. In addition, a single concentration of H2S donor NaHS (1 μM) dilated small mesenteric arteries (<100 μm) but had no effect in large mesenteric arteries (>300 μm). Furthermore, inhibiting CSE generation of H2S with β‐cyanoalanine (BCA, 100 μM) impaired acetylcholine (ACh)‐induced dilation in small mesenteric arteries, but had no effect in large mesenteric arteries. These data suggest that H2S‐induced dilation is prominent and important in small resistance arteries but not in larger arteries. It is possible that decreased availability of TRPV4 and/or BK in larger arteries is responsible for the diminished sensitivity to H2S‐induced vasodilation. Previous reports suggest that membrane cholesterol negatively regulates TRPV4 mobility and BK activity. Our current study tested the hypothesis that H2S‐mediated vasodilation is inhibited by membrane cholesterol. Mesenteric arteries induced vasodilation was assessed in pressurized large rat mesenteric arteries (>300 μm). Isolated pressurized mesenteric arteries (320 μm – 360 μm) were pretreated luminally with vehicle (HEPES) or the cholesterol‐depleting agent, methyl β cyclodextran (MBCD, 100 μM) and exposed to NaHS (100 μM). NaHS‐induced dilation in U46619 pre‐constricted arteries was significantly enhanced by MBCD pretreatment (+vehicle: 6.78% ± 1.6, +MBCD: 17.10% ± 6.8, p < 0.05, n=3–4 animals/group). These studies suggest that membrane cholesterol disrupts H2S‐mediated vasodilation. Ongoing studies in isolated mesenteric arteries of different sizes are investigating endothelial cell membrane cholesterol content and the effect of cholesterol depletion on TRPV4‐dependent Ca2+ influx in large and small mesenteric arteries.Support or Funding InformationFunding provided by the NIH HL12330 & HL7736‐23This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Translational value of mechanical and vasomotor properties of mouse isolated mesenteric resistance-sized arteries.

Mice are increasingly used in vascular research for studying perturbations and responses to vasoactive agents in small artery preparations. Historically, small artery function has preferably been studied in rat isolated mesenteric resistance‐sized arteries (MRA) using the wire myograph technique. Although different mouse arteries have been studied using the wire myograph no establishment of optimal settings has yet been performed. Therefore, the purposes of this study were firstly to establish the optimal settings for wire myograph studies of mouse MRA and compare them to those of rat MRA. Second, by surveying the literature, we aimed to evaluate the overall translatability of observed pharmacological vasomotor responses of mouse MRA to those obtained in rat MRA as well as corresponding and different arteries in terms of vessel size and species origin. Our results showed that the optimal conditions for maximal active force development in mouse MRA were not significantly different to those determined in rat MRA. Furthermore, we found that the observed concentration‐dependent vasomotor responses of mouse MRA to noradrenaline, phenylephrine, angiotensin II, sarafotoxin 6c, 5‐hydroxytryptamine, carbachol, sodium nitroprusside, and retigabine were generally similar to those described in rat MRA as well as arteries of different sizes and species origin. In summary, the results of this study provide a framework for evidence‐based optimization of the isometric wire myograph setup to mouse MRA. Additionally, in terms of translational value, our study suggests that mouse MRA can be applied as a useful model for studying vascular reactivity.

Vasorelaxant activities of Danhong injection and their differential effects on the rat abdominal aorta and mesenteric artery.

Previous studies have found that Danhong injection (DHI), an extensively used herbal extract preparation in China, might be a powerful vasodilator. The aims of this study were to determine the vascular activity of DHI and its effects on arteries of different sizes. The results showed that DHI significantly inhibited rat-hindquarters and rabbit-ear vasoconstriction elicited by norepinephrine (NE) perfusion and markedly relaxed KCl-contracted and NE-contracted rat abdominal aortic and mesenteric artery rings. The endothelium made only a minor contribution to the vasorelaxant effect of DHI on artery segments. The vasorelaxant effect of DHI varied with the artery size, with larger arteries exhibiting a more sensitive and potent vasodilator response. DHI relaxed NE-induced vasoconstriction probably through inhibition of the intracellular Ca2+ release through the inositol triphosphate receptor system in the abdominal aorta and mesenteric artery, along with blockage of extracellular Ca2+ influx through the receptor-linked Ca2+ channels in the mesenteric artery. In addition, DHI completely relaxed KCl-induced contraction in both of the arteries, suggesting that inhibition of Ca2+ influx through voltage-gated Ca2+ channels is involved in the vasorelaxant effect of DHI. This elucidation of the vascular effects of DHI and the underlying mechanisms could lead to improved clinical applications.

Role of shear stress on nitrite and NOS protein content in different size conduit arteries of swine

Inherent fundamental difference exists among arteries of different sizes. The purpose of this study was to evaluate the relation between regional difference of wall shear stress (WSS) in various sizes arteries and contents of nitrite and NO synthase (NOS) isoforms. Five different conduit arteries in a wide range of diameter (1-8 mm) were examined in the hind limbs of 13 pigs. Blood flow rate and outer diameter were measured in vivo to determine WSS. Arterial tissues were harvested for the measurement of nitrite and NOS protein contents. The concentration of nitrite, a product of NO synthesis, was determined by high-performance liquid chromatography method. Western blot analysis was used to assess the protein contents of endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS). Our data show that WSS increases with a decrease in artery diameter. Nitrite level increases with increasing WSS and hence decreases with artery diameter. The eNOS protein contents decrease with an increase in diameter. No significant difference for iNOS and nNOS protein contents was found with different artery diameter. A significant positive correlation between tissue nitrite and eNOS protein contents was also observed. Finally, the WSS-normalized eNOS is not significantly different in various size vessels. Regional difference in blood flow has no effect on iNOS and nNOS protein contents in these conduit arteries. Regional difference in eNOS expression and nitrite contents may be related to the WSS-induced NO by the endothelium under normal physiological conditions.

Mechanical function of intermediate filaments in arteries of different size examined using desmin deficient mice.

Protein composition and mechanical function of intermediate filaments were examined in arteries of different sizes using desmin deficient mice (Des-/-) and their wild-type controls (Des+/+). Using SDS-PAGE gels and Western blots we found a gradient in desmin expression in the arterial tree; the desmin content increased from the elastic artery aorta, via the muscular mesenteric artery to the resistance-sized mesenteric microarteries approximately 150 microm in diameter in Des+/+ mice. Mechanical experiments were performed on the aorta, the mesenteric artery and resistance-sized arteries using wire myographs. For aorta and mesenteric artery, no differences in passive or active circumference- stress relations were found between Des-/- and Des+/+ mice. In microarteries, both passive and active stress were lower in the Des-/- group. In conclusion, large elastic and muscular arteries contain a relatively low amount of desmin, and the desmin intermediate filaments do not seem to play a major role in the mechanical properties of these larger arterial vessels. In the microarteries, where expression of desmin is high, desmin plays a role in supporting both passive and active tension.

P2X Receptor Immunoreactivity in Different Arteries from the Femoral, Pulmonary, Cerebral, Coronary and Renal Circulations

The expression of the seven P2X receptor subunits (P2X_1–7) in the rat vascular system was determined using subtype-selective antibodies. Arteries of different sizes (from arterioles to conduit vessels) from a range of vascular beds were used to give an overview of receptor expression. P2X₁ receptor immunoreactivity was detected in the smooth muscle layer of arteries. The relative level of P2X₁ receptor immunoreactivity was dependent on the size of the artery and the vascular bed; expression was highest in small and medium arteries. P2X₄ receptors were detected in all arteries; once again, the relative level of expression was dependent on the size of the artery and the vascular bed. P2X₅ receptor immunoreactivity was barely detectable in most arteries studied. P2X₇ receptor immunoreactivity was generally punctate and associated with the outer adventitial layer. Immunoreactivity for P2X₂, P2X₃ and P2X₆ receptors was not detected in arteries. These results demonstrate that arteries express multiple P2X receptor subunits and that there is a heterogeneity in the level of expression. The properties of artery P2X receptors correspond to homomeric P2X₁ receptors, and the function of P2X₄ and P2X₅ receptor subunits in arteries is unclear.

Transbrachial Endovascular Exclusion of an Axillary Artery Pseudoaneurysm with PTFE-Covered Stents

Purpose: Endovascular exclusion of arterial injuries associated with arteriovenous fistulas and pseudoaneurysms has only recently been described using various stent-graft prostheses. This report details a transbrachial technique used to exclude an axillary artery pseudoaneurysm developing at the axillary anastomosis of an axillofemoral graft. Methods and Results: Thin-walled polytetrafluoroethylene was expanded with an angioplasty balloon catheter and used to cover standard Palmaz stents. Two covered stents were delivered under fluoroscopic guidance via open brachial artery access to the site, resulting in complete exclusion of the pseudoaneurysm. Follow-up duplex scanning confirmed aneurysm exclusion 3 months postprocedure. Conclusions: This technique can be applied in arteries of different sizes and lengths, using currently available materials. However, the long-term behavior of these devices in the arterial tree must be determined before their widespread use can be recommended for most indications.

Vasorelaxant mechanism of KRN2391 and nicorandil in porcine coronary arteries of different sizes.

1. The relaxant mechanisms of action of KRN2391, a novel vasodilator, and nicorandil on epimyocardial coronary artery (2.5- 3.0 mm outer diameter) and mid-myocardial coronary artery (0.8-1.0 mm outer diameter) were investigated in porcine isolated coronary arteries. In addition, the vasorelaxant responses of KRN2391 and nicorandil were compared with those of nitroglycerin and cromakalim, a K+ channel opener, in epi- and mid-myocardial coronary arteries. 2. Nitroglycerin showed a more potent relaxant effect on epi-myocardial coronary arteries than on mid-myocardial coronary arteries, whereas cromakalim produced greater relaxation responses in mid-myocardial coronary arteries. There was no difference between epi- and mid-myocardial coronary arteries in terms of the relaxant effect of KRN2391 and nicorandil. 3. Relaxation induced by KRN2391 in epi- and mid-myocardial coronary arteries was inhibited by oxyhaemoglobin, a pharmacological antagonist of nitrovasodilators, and glibenclamide, a pharmacological antagonist of K+ channel opening drugs. However, the inhibitory effect of glibenclamide on KRN2391-induced relaxation was greater in mid-myocardial coronary artery than in epi-myocardial coronary artery. 4. Relaxation induced by nicorandil was inhibited by oxyhaemoglobin alone in epi-myocardial coronary arteries and by both oxyhaemoglobin and glibenclamide in mid-myocardial coronary arteries. 5. In epi- and mid-myocardial coronary arteries, relaxation induced by cromakalim was inhibited by glibenclamide but not by oxyhaemoglobin, whereas relaxation induced by nitroglycerin was inhibited by oxyhaemoglobin but not by glibenclamide. 6. These results suggest that KRN2391 and nicorandil exhibit a dual mechanism of action acting partly as a nitrate and partly as a K+ channel opener. The mechanism of action of these drugs depend on the segment of coronary artery studied. Furthermore, the dual mechanism of action of KRN2391 and nicorandil seems to contribute to the equipotent relaxant effect between epi- and mid-myocardial coronary arteries.

A method for the isolation of cells from arteries of various sizes

This report describes a technique for the isolation of smooth muscle cells (SMC) from arteries of different sizes. SMC from dog carotid arteries were dissociated by collagenase-elastase perfusion under constant pressure. The freshly isolated cells were spindle shaped with an average length of 118.0 + 8.0 μm. A distinct basal lamina, ovoid nucleus, and both thick and thin filaments were observable by transmission electron microscopy. Scanning electron microscopy of the cells revealed a continuous plasma membrane and several fingerlike processes. A chamber used to study the contractile properties of isolated cells is also described. Studies of the contractile properties of SMC isolated by this technique found that cells exposed to calcium (2.5 mM) or potassium (50 mM) or both contracted by 25 to 35%. Thus, SMC isolated by the collagenase-elastase perfusion technique described here possess morphologic and contractile characteristics typical of SMC.

Comparison of the Direct Effects of Halothane and Isoflurane on Large and Small Coronary Arteries Isolated from Dogs

Relaxant responses to halothane and isoflurane were compared in helical strips of dog epicardial coronary arteries of different sizes: proximal large coronary arteries with outside diameters (OD) larger than 2.5 mm and distal small arteries with 0.7-0.9 mm OD. Responses to pharmacologic vasodilators, including nitroglycerin (NTG) and adenosine, were also studied for comparison. The relaxation induced by halothane in concentrations of 0.8-2.3% and by NTG (10(-9)-10(-5) M) was greater in proximal large coronary arteries than in distal small ones contracted with 20 mM KCl. In contrast, the relaxation by isoflurane (1.2-3.5%) and by adenosine (10(-8)-10(-4) M) was greater in small coronary arteries than in large ones. These results suggest that isoflurane is, like adenosine, preferentially a small artery dilator.

The Regional Difference of Relaxations Induced by Various Vasodilators in Isolated Dog Coronary and Mesenteric Arteries

Relaxant responses to vasodilators, including nitroglycerin, sodium nitroprusside, prostaglandin I2 sodium salt (PGI2), prostaglandin E1 (PGE1), diltiazem hydrochloride and adenosine, were compared in heiical strips of dog coronary arteries of different sizes and in coronary and mesenteric arterial strips. The relaxant responses to nitroglycerin, sodium nitroprusside, diltiazem and adenosine were significantly greater in coronary arteries than in mesenteric arteries, whereas the responses to PGI2 and PGEt in these arteries did not significantly differ. In coronary arteries of different sizes, the relaxation induced by nitroglycerin was in the order of large>medium>small-size, while in contrast, the relaxations by adenosine, PGI2 and PGE1 were greatest in the small-size arteries and least in the large-size arteries. The relaxant responses to sodium nitroprusside and diltiazem did not differ in the coronary arteries of different sizes. Nitroglycerin, sodium nitroprusside and diltiazem appear to dilate coronary arteries more predominantly than mesenteric arteries. The preferential dilator action of PGI2 and PGE1 on distal coronary arteries, like that of adenosine, may lead more blood to re-distribute to the non-ischemic region of the heart in anginal patients.

Response of isolated monkey coronary arteries to catecholamines and to transmural electrical stimulation.

In helically cut stripes of monkey coronary arteries of different sizes, contracted with prostaglandin F2 alpha or K+, responses to norepinephrine, epinephrine, isoproterenol, and transmural electrical stimulation were compared. In response to norepinephrine, only contractions were induced in large arteries, contractions at low concentrations and relaxations at high concentrations in medium-size arteries, and only relaxations in small arteries. Epinephrine produced a greater contraction than norepinephrine in the arteries. Relaxant effects of isoproterenol were greater in small and medium-size arteries than in large arteries. Transmural electrical stimulation applied at frequencies of 2,5, and 20 Hz to strips of medium-size arteries produced a frequency-dependent contraction that was reversed to a relaxation following treatment with phentolamine. Propranolol abolished the relaxation. In strips of dog coronary arteries of medium size, transmural stimulation elicited only a relaxation which was suppressed or reversed to a contraction by propranolol. Dog arteries of this size responded to norepinephrine and epinephrine with only a relaxation. It may be concluded that the quantity or the susceptibility of alpha-adrenoceptors is in the order of large greater than or equal to medium greater than small-size arteries from monkeys, whereas that of beta-adrenoceptors is in the order of medium = small greater than large arteries. Monkey coronary arteries appear to respond to endogenous and exogenous norepinephrine with a contraction more consistently than dog coronary arteries.

On the “normalization” of active developed force of isolated helical strips of muscular and elastic arteries for variation in wall thickness

Responses of helical strips of ventral tail (muscular) and anterior mesenteric (elastic) artery of rats of two different sizes to a fixed concentration of norepinephrine (NE, 6 × 10 −7M) were plotted versus incremental levels of resting tension. In addition, complete NE cumulative dose-response curves (6 × 10 −10to 6 × 10 −4M) were obtained at the optimal resting tension of each strip. Thirteen measurements or calculations of strip dimensions were made on each vessel and active developed force was divided by each of the dimensions. Vessels from larger rats had thicker walls. The active versus resting tension curve for the muscular artery was steeper and thus determination of optimal resting tension is more critical in this artery. Among the measurements used, active developed force of the muscular artery strip was best “normalized” for variation in wall thickness when expressed as percentage or force per unit of total or tunica media crosssectional area. Active developed force of the elastic artery strip was best “normalized” for variation in wall thickness when expressed as percentage or per unit of total volume. NE dose-response curves have substantially different appearances when responses are expressed in alternative ways. In conclusion, careful attention to these technical details is necessary in comparison of active developed force in arteries of different sizes. Different techniques may be needed for muscular and elastic arteries.

Ultrasonic diagnosis of arterial aneurysms.

In the present work attempts have been made, with the aid of ultrasonic scanning, A-presentation, and TM-Mode, to demonstrate the cross-section of arteries of different sizes, both in vitro and in vivo. In this connection a material is presented consisting of 10 aneurysms of the femoral artery and 4 aneurysms of the abdominal aorta—all demonstrated by means of ultrasound. It is concluded that the method is well suited for the selection of cases, clinically suspected of aneurysms, for ateriography, and, as a supplementary form of investigation, since the method is superior to arterography in providing information on the actual size of the aneurysm.