bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of the Vasa Vasorum Network in the Uterine Arteries of Domestic and Wild Mammals
Authors: Neumann F.
Published: September 2008

The vasa vasorum patterns in the uterine arteries of virgin and multiparous domestic and wild mammals were investigated. In young virgin females the vasa vasorum network was present in the adventitia. The uterine arteries of adult multiparous females showed various degrees of intimal hyperplasia and the adventitial vasa vasorum were piercing the arterial wall. The depth of penetration was related to the degree of intimal hyperplasia, namely, to the thickness ratio between the intima and media. Intimal vascularisation occurred in those arteries in which the hyperplastic intima overpassed the thickness of the media. These capillaries originated from the adventitial vasa vasorum network and were penetrating transmedially.
X-Ray, Light and Electron Microscopic Observations in Experimental Lymphostasis of the Liver
Authors: Huth F. , Wilde A. , Schulten H.J. , Berger S. , Davaris P. , Baden E.
Published: September 2008

Experimental lymph stasis demonstrates the hepatic lymph vessel system by unfolding of the branching lymphatics. The lymphatics are limited to the interlobular connective tissue. The lymphatic wall consists of a flat endothelium without pores and without a continuous basal membrane. The endothelial cells show overlapping processes and are suspended in a net of delicate filaments. Lymph and bile stasis produce separation of the endothelial junctions. Only reversible changes of liver parenchyma are seen after pure lymphostasis. The storage of tantalum powder by the liver is reduced by the Imphostatic edema. The significance of lymph stasis resides primarily in its existence as an additional stressor. Simultaneous lymph and bile stasis definitely speeded up the cirrhotic process. The experimental models should lead to a greater emphasis of the importance of the hepatic lymphatic drainage system, and especially of lymphostasis as an important additional factor in pathogenesis of human diseases.
Enzymes in the Wall of Normal and Varicose Veins
Authors: Urbanová D. , Přerovský I.
Published: September 2008

An examination was made of 10 samples of the great saphenous vein, removed from persons without varices and serving as the control group. A further 20 samples of typical varices, as well as 20 samples of normal veins obtained from persons with varices, were examined. The venous walls were tested for activities of certain hydrolytic enzymes and dehydrogenase systems. In both the varicose veins and the normal veins obtained from persons with varices it was found that structural changes occur and histochemical tests show a marked increase in the activity of acid phosphatase and decreased activities of malate dehydrogenase, non-specific esterase, ATPase, and 5-nucleotidase. An increased activity of the lactate dehydrogenase was found only in 55 % of the cases. In normal veins obtained from persons with varices, these changes were less pronounced. The layer of the circular muscle cells of the media is the zone of a varicose vein which sustains the heaviest damage.
Effect of O-(β-Hydroxyethyl)-Rutosides on Oedema in Chronic Venous Insufficiency of the Lower Limb
Authors: Rish L. , Rodriguez J.C.
Published: September 2008

O-(β-hydroxyethyl)-rutosides (HR) was compared with placebo in a double blind trial lasting 1 month in patients suffering from oedema, pain, heaviness and cramps in the lower limbs associated with chronic venous insufficiency. HR was significantly more effective than placebo in reducing oedema. There also appeared to be a greater effect on pain, heaviness and cramps.
Adjustment Behavior of Adrenergic-Induced Vasoconstrictions in the Intestinal Circulation of the Cat
Authors: Henrich H.
Published: September 2008

Adrenergic-induced vasoconstrictions are succeeded by an adjustment reaction (‘escape phenommenon’ or ‘autoregulatory escape’) and after the end of stimulation by a postconstrictive dilation (‘reactive hyperemia’)- These vascular reactions have been examined on the intact mesenteric circulation of the cat by performing frequency-response curves (5 and 10 V, 1 msec. 1–50 Hz). An electrotonic blockade and a local summation could be excluded as the cause of the escape within the physiological range. The maximum of the initial reaction was found at a stimulation strength between 12 and 16 V (10 Hz, 1 msec). The maximum of the escape reaction occurred at 5 V. Both vascular reactions were strongly dependent on the local concentration of noradrenaline (i.a. infusion); however, they reached their maximum at different concentrations. The escape reaction is apparently a persisting adjustment to a steady state. Despite a formal similarity, no correlation could be demonstrated between the postconstrictive dilation and the escape reaction. Both vascular adjustment reactions are of myogenic origin. It is concluded that the reason for the escape phenomenon can not be found in the local or propagated nerval response, in the transmitter release, or in its effect on the vascular smooth muscle. But it is suggested that the escape reaction is a form of myogenic, autonomic adjustment behavior.
Altersabhängigkeit der Gefässwandpermeabilität für Makromoleküle bei Kaninchen
Authors: Hauck G. , Schröer H.
Published: September 2008

In rabbits subdivided in three groups of different age, vitalmicroscopic investigations were performed concerning the comparative studies of the microcirculation and microvessel permeability for proteins. The normal brightfield, incomplete darkfield, and bluelight luminescence techniques were used. Young rabbits showed a typical pattern of protein permeation mainly localized on the venous end of the capillary bed with maximum along the venules and participation of capillaries and small collecting veins. The postcapillary blood flow was marked by a considerable instability because of increased tendency to red cell aggregation and blood flow anomalies. The findings obtained in middle-aged rabbits were similar to the results of young rabbits. The findings in the third group of old animals, however, were clearly different in comparison with group 1. The protein permeability remained restricted on the venules and was remarkably diminished. Consequently, the intravascular luminescence persisted for 1 h and more, and the small vessels appeared very sharply delimitated against the extravascular space because of absence of a perivascular luminescence. The postcapillary blood flow seems to be stabilized, and prestasis was extremely rare. The diminution or absence of a protein passage across the capillary wall and interstitial space of old animals is interpreted as an important component responsible for the aging process of tissues and organs.
Kräfte und Kraftwirkungen im Gebiet der Blutkapillaren
Authors: Kuhnke Eberhard
Published: September 2008

The equations of state for the forces acting between the intra- and extracapillary spaces have been developed, and their significance in the filtration and reabsorption properties of the blood capillaries are shown.
Lymphatic Porosity as a Consequence of Complex Vitamin B Deficiency in the Rat
Authors: Földi-Börcsök Ethel , Collard M. , Földi M.
Published: September 2008

Lymphatic porosity was produced by feeding rats a diet, lacking from the vitamins of the B group. Coumarintroxerutin (Venalot®) treatment has been found to prevent this abnormality. Pathophysiologic and therapeutic implications of these findings are discussed.
Vascular Alterations in Adenomas of Human Pituitary Glands
Authors: Kovacs K. , Horvath E.
Published: September 2008

Electron microscopy of 18 human pituitary adenomas revealed vascular abnormalities consisting of thickening of endothelial lining, endothelial swelling, endothelial blebbing, accumulation of microfilaments in the cytoplasm of the endothelial cells, partial or total loss of fenestration, and, rarely, thickening of basement membrane. Disturbance of pituitary microcirculation, possibly due to alteration of intrahypophysial pressure, can result in hypoxia. This might play an important role in the genesis of changes of vasculature. Lesions of the pituitary vessels occur not infrequently. If severe, they may interfere with exchanges of O2 and metabolic products and may alter permeability across the vascular walls. Their further progress may cause irreversible damage to the tumor cells, leading ultimately to hemorrhage and infarction of the tumor.
Angiographic Diagnosis of Leiomyomatous Small Bowel Tumors
Authors: Itzchak Y. , Adar R. , Mozes M. , Deutsch V.
Published: September 2008

The angiographic features of leiomyomatous tumors of the small bowel are described in three cases. Selective celiac and superior-mesenteric angiography disclose large, sometimes multiple, feeding arteries and draining veins. There are many irregular tumor vessels and dense staining, venous pooling and early venous filling. The margins are well circumscribed and correspond to the true size of the mass. The differential diagnostic problems between benign and malignant leiomyomatous lesions and the angiographic features of metastatic leiomyosarcoma in the omentum and the liver are also described.
Pharmacology of the Aorta
Authors: Fleisch Jerome H.
Published: September 2008

This brief review discusses some aspects of drug action on the spirally cut mammalian aorta. Drugs interact with one or more of five major areas: nerves innervating the tissue; drug receptors presumably located on the membrane; one of the steps in the sequence of events connecting the receptor with the contractile apparatus; the membrane itself, and the contractile proteins. Aortic responses to drugs are influenced by various factors including species variation, hormones, and aging. Ca++ mobilization appears to be the central step in the overall control of vascular smooth muscle responsiveness.
Development of Vascular Reactivity in Chickens: Responses of Mesenteric and Hind-Limb Blood Vessels to Norepinephrine and Acetylcholine
Authors: Knight A. , McGregor D.D.
Published: September 2008

Mesenteric arteries and the hind-limb vasculature supplied by the sciatic artery were isolated from chickens 0–25 vity days after hatching and perfused with physiological saline. Mesenteric arteries gave only small responses to norepinephrine until the 2nd week after hatching when there was a striking increase in their reactivity. Hind-limb blood vessels were much more responsive to norepinephrine from the 1st day. The height of vasoconstrictor responses in hind-limbs showed no marked change with age but the duration of responses decreased as chickens grew older. The duration of responses to norepinephrine increased when perfusion temperature was lowered from 40 to 20 °C. Acetylcholine produced vasodilatation in mesenteric and hind-limb blood vessels. It is concluded that the receptor mechanisms for adrenergic and cholinergic control of hind-limb blood flow are functional at or before hatching. The increase in vascular reactivity to norepinephrine in mesenteric arteries coincides with reported increases in blood pressure and thermoregulatory ability of chickens and may contribute to these increases.
Influence of Papaverine and Nitrite on the Responses to Norepinephrine of Inner and Outer Smooth Muscle of Sheep Carotid Arteries
Authors: Keatinge W.R. , Graham J.M.
Published: September 2008

Inner muscle of sheep carotid arteries responded to norepinephrine in lower concentration, and with a larger initial contraction, than outer muscle. Initial contractions of both tissues did not require external Ca but stable contractions did. Papaverine greatly depressed stable but not initial contractions, causing inner muscle to respond to each effective concentration of norepinephrine by contraction followed by relaxation. Papaverine particularly depressed the stable responses of inner muscle to low concentrations of norepinephrine. Nitrite generally caused changes in response qualitatively similar to those produced by papaverine.
Influences of Calcium Concentration and pH on the Tension Development and ATPase Activity of the Arterial Actomyosin Contractile System
Authors: Mrwa U. , Achtig I. , Rüegg J.C.
Published: September 2008

‘Chemically skinned’ muscle fibre bundles of pig carotid arteries and natural actomyosin from the arterial media were compared. In both cases the concentration of Ca++ ions required for half maximal tension development and 50% activation of the Mg++-activated ATPase was similar and strongly pH dependent (10–4 m at pH 6; 10–6 m at pH 7). The optimum pH for contraction and Mg++-activated ATPase activity of glycerinated fibre bundles was found to be near neutrality, while it was below six in the case of A dilute natural actomyosin. This discrepancy seemed to be due to the fact that at pH 6 the actomyosin was insoluble. Neutralization in the presence of Mg++-ATP solubilized natural arterial actomyosin even at low ionic strength. This solubilization inhibited the apparently gel dependent actomyosin ATPase activity. This inhibition could be reversed if the gel formation was produced by increasing the protein concentration: the activity rose to the higher level characteristic for actomyosin in the gel state within glycerinated fibres.
Relation of c-AMP to Relaxation of Pulmonary Artery
Authors: Daniel E.E. , Crankshaw Jean
Published: September 2008

We tested the hypothesis that an increase in c-AMP was necessary or sufficient for relaxation of rabbit pulmonary artery. Isoproterenol (INA) partially relaxed serotonin (5-HT) induced contractions. Theophylline (TH) alone relaxed contraction more effectively, but after TH, INA produced no greater relaxation. At the height of relaxation (2 min), c-AMP was not increased, but after 5 min the c-AMP was decreased and the artery was recontracted. c-AMP was increased after TH, and more when INA was given after TH. Noradrenaline contracted the arteries and increased c-AMP; both effects were prevented by phentolamine. A series of other relaxants (papaverine, nitroglycerine, D600, Ro-7-2956, diazoxide and dipyridamole) also failed to produce relaxations directly related to c-AMP levels. We concluded that c-AMP increase was not necessary or sufficient for relaxation in artery, and that in pulmonary artery phosphodiesterase activity played an important role in determining tissue levels of c-AMP.
Cyclic AMP Blood Vessels of Spontaneously Hypertensive Rat
Authors: Ramanathan S. , Shibata Shoji
Published: September 2008

The vascular smooth muscle (aorta, portal vein and renal arteries) from spontaneously hypertensive rats (SHR) contained a lower level of cyclic adenosine-3’5’-monophosphate (cyclic AMP). Similar differences were observed in young SHR that had not yet developed hypertension, as compared to their normotensive controls. However, no such difference was observed in the vascular smooth muscle from the cross-bred normotensive animals. The adenyl cyclase and phosphodiesterase activities of the vascular smooth muscles from SHR was lower than the normotensive controls. It is suggested that changes in cyclic AMP metabolism occur during the process of hypertension.
Response of the Rabbit Coronary Arteries to Autonomic Agents
Authors: de la Lande Ivan S. , Harvey JudithAnn , Holt Suzanne
Published: September 2008

The right or left coronary arteries were constricted by cholinergic agents and dilated by adrenergic agents. The receptors mediating cholinergic responses are muscarinic. Comparison with the ear artery indicates that the adrenergic receptors mediating dilatation in the coronary artery resemble β1 rather than β2. However, the ratios of the dilator potencies of noradrenaline, adrenaline and isoprenaline on the coronary artery were 1:0.23:2.6 compared with ratios of their positive inotropic potencies of 1:1.1:33 on the rabbit papillary muscle. The markedly smaller relative potency of noradrenaline on the papillary muscle may be due to uptake1, since the potentiating effect of cocaine on noradrenaline on this tissue was approximately 12-fold, but was negligible on the coronary artery. The contribution of uptake2 is unclear, since histochemical observations indicated selective accumulation of noradrenaline in the wall of the artery, whereas the dilator responses were not appreciably altered by uptake2 inhibitors.
Vibration-Induced Inhibition of Vascular Smooth Muscle Contraction
Authors: Ljung Bengt , Sivertsson Ramon
Published: September 2008

Vascular smooth muscle is known to be exposed to an oscillating strain under physiological and pathophysiological conditions as well as in different occupational and environmental situations. The effect of vibrations on smooth muscle seems to be largely unknown. In the present experiments on isolated preparations of the rat portal vein and the rabbit thoracic aorta, imposed sinusoidal changes in length were found to cause prompt reduction in active force, the extent of which was dependent on amplitude (1–10% of tissue length, peak to peak, i.e. approximately ± 50–500 µm) and frequency of vibration (1–400 Hz) as well as on the prevailing level of active and passive forces. Vibrations caused only small and inconsistant reductions of passive force of the vascular smooth muscle. The results are in accordance with the hypothesis that vibrations exert a direct action on the contractile process by causing an increased rate of detachment of actin-myosin cross-links. It is suggested that, in vivo, vibrations may affect the diameter of conduit arteries locally in the case of turbulent blood flow as seen in post-stenotic dilatation and arterio-venous anastomosis. Possibly, even the normal pulse pressure oscillations may sometimes tend to inhibit the smooth muscle activity in such arteries and thereby influence their diameters.
Ajmaline-Induced Changes in Mechanical and Electrical Activity of Vascular Smooth Muscle
Authors: Biamino Giancarlo , Wessel Hans-Joachim , Nöring Jutta
Published: September 2008

The effects of ajmaline on vascular smooth muscle were studied using helical aortic strips and portal veins of male rats. This report is based on the results of 104 mechanical experiments. In 30 additional experiments electrical activity was recorded simultaneously at different points of the preparation using extracellular methods (liquid paraffine or pressure electrodes technique). Ajmaline induces relaxation of aortic helical strips (activated by 2.0 µg/l norepinephrine) to 75% of initial tension in a dose of 0.6 mg/l, to 50% by 2.0 mg/l, and to 25% by 4–5 mg/l. The relaxation slope is shifted to the right by increasing the [Ca++]o from 2.0 to 4.0 mM, by increasing the initial norepinephrine concentration to 4.0–10 µg/l, or by KC1 depolarization, [K+]o ranging from 15 to 60 mM.The relaxing effect of ajmaline on aortic strips can partly be attributed to a change in electrical activity with a dose-dependent conduction impairment or block and, at high concentrations, also a decrease in the frequency of pacemaker excitations. Experiments on aortic strips in K+ contracture show relaxation independent of changes in phasic electrical events. Ajmaline ranging from 0.2 to 80–100 mg/l causes on the portal vein a marked increase in amplitude and a small decrease in frequency of rhythmical contractions. Integrated isometric force reaches 300% of initial values. The increasing amplitude of contractions is related to a prolongation of excitation trains, while the frequency and amplitude of the individual spike are reduced.Our results suggest that the effects of ajmaline on the mechanical and electrical activity of vascular smooth muscle may be partly related to a reduction in Ca++ and probably Na+ conductance.
Effect of Sex Hormones on Rabbit Arterial Subendothelial Connective Tissue
Authors: Gaynor Evelyn
Published: September 2008

The effect of sex hormones on subendothelial connective tissue in rabbit arteries was sought, and striking morphological alterations were noted after prolonged treatment. Depot preparations of testosterone cypionate, 100 mg/week, or estradiol cypionate, 200 µg/week, were injected intramuscularly into intact adult New Zealand male rabbits for 8–16 weeks. The iliac arteries were prepared for electron-microscopic examination from five rabbits in each treatment group and in four normal male rabbits. Thin sections were prepared from three randomly selected cross-sectional tissue blocks for each animal. A minimum of 7 µm of vessel circumference was studied in each block. Selection of an area for electron-microscopic examination was random, except that those sites in which the internal elastic lamina showed fragmentation were discarded. Electron micrographs at a single final magnification were evaluated ‘blind’ by several observers for qualitative difference in subendothelial constituents. In the control group, the subendothelium contained moderate numbers of elastin-associated microfibrils (MF); all the rabbits given testosterone consistently showed significantly fewer MF than the control. In contrast, rabbits given estradiol all had significantly greater numbers of MF. Statistical analysis of variance showed these difference to be significant at p < 0.001.
Concerning the Role of the Amine Pump of the Adrenergic Innervation of Rabbit Aorta in Sustaining the Neuron Blockade Produced by Bethanidine and Bretylium
Authors: Maxwell R.A. , Eckhardt Batmanglidj
Published: September 2008

Adrenergic neuron blockade produced in rabbit aortic strips by bretylium and bethanidine has been studied. Differences were noted in the characteristics of approximately equal, strong neuron blockade produced by these two chemically different agents. The blockade produced by bretylium was readily reversed by washout of the drug from the tissue bath whereas blockade produced by bethanidine was slowly reversed. Desmethylimipramine accelerated the recovery after the washout of bretylium, but had little effect in accelerating recovery following the washout of bethanidine. Desmethylimipramine prevented the onset of blockade from bretylium whereas it only delayed the onset of blockade from bethanidine. Desmethylimipramine also completely antagonized an established blockade due to bretylium but only slightly antagonized an established blockade due to bethanidine. It is suggested that the differences observed between these two neuron blocking agents are the result of their differential retention inside the neuron: bretylium is not firmly bound, leaks out of the neuron and goes through a process of recycling across the cell membrane, while bethanidine is more firmly bound inside the neuron than bretylium, only slowly leaks out of the neuron and is not recycled back across the cell membrane.
Evidence for Non-Mast Cell Histamine in the Vascular Wall
Authors: El-Ackad Tarek M. , Brody Michael J.
Published: September 2008

Histamine has been found biochemically in the mammalian vascular wall. This study was undertaken in an effort to identify the presence of specific histamine-containing cells in walls of large blood vessels such as femoral artery and vein, brachial artery and vein, mesenteric artery and vein, renal artery and vein, and aorta. Segments of vessels from rats, cats, dogs, sheep, cows, humans and chickens were examined. Sections were prepared from fresh tissue by vibratome, from frozen tissue by cryostat and from freeze-dried and fixed tissues. Mast cells were visualized by staining with acidic toluidine blue and by reaction with orthophthalaldehyde to develop histamine fluorescence. Although mast cells were easily identified in preparations such as canine liver, ear and scrotal skin and rat tongue, no such cells were found in any species (except the cow) in any part of the vascular wall. The results indicate that in most species histamine is stored in the vascular wall in a non-mast cell pool which may well be in the smooth muscle cells themselves.
Comparison of Net Fluxes of Li and Na in Vascular Smooth Muscle
Authors: Friedman Sydney M.
Published: September 2008

The rat tail artery enriched by incubation in a lithium-substituted medium loses Li at three distinct rates upon return to a normal medium at 37 °C. The first is very rapid with a single exponential rate constant of the order of 1 min–1, while the second and third are considerably slower with rate constants of the order of 3 h–1 and 0.6 h–1, respectively. Both slow components are cellular since they combine into a single component when active Na transport is inhibited by the absence of external K, by ouabain, or by low temperature. None of these procedures affects the rapid loss of Li from extracellular locations. It follows that cell Li can be measured simply by washing out extracellular Li at 2 °C, a procedure which removes only a small definable amount from cells. The influx of Li into cells during incubation in Li-substituted medium follows 1st order kinetics and exchanges 1:1 with cell K after a delay of about 20 min at 37 °C. This delay in influx is associated with active Na transport since it is abolished by the absence of external K, by low temperature, and by ouabain. The activation energy required for the influx of Li and of Na in K-free media is consistent, in the main, with passive diffusion through a restricted area although there is a suggestion in the case of Na that an additional mechanism (e.g. carrier) may be involved.
Effects of Neomycin on 45Ca Binding and Distribution in Canine Arteries
Authors: Goodman Frank R. , Adams Richard , Weiss George B.
Published: September 2008

The effects of neomycin (7.0 mM) on 45Ca movements and distribution were investigated in canine aortae and in canine carotid and terminal mesenteric arteries. Uptake of 45Ca was measured in calcium-free solution; the 45Ca tissue spaces in the carotid and terminal mesenteric arteries were 2–4 times greater than those observed in the aorta. Exposure of the aortae and the terminal mesenteric arteries to 1.5 mM Ca++ during the washout elicited large increases in 45Ca efflux in both preparations (increase in terminal mesenteric > aorta). Moreover, in all three arterial preparations, neomycin reduced 45Ca uptake and induced a sustained increase in 45Ca efflux (effects on terminal mesenteric > carotid > aorta). The terminal mesenteric and carotid arteries may accumulate and bind 45Ca at superficial membrane sites (readily exchangeable 45Ca) to a greater degree than does the aorta. If Ca++ located at these membrane sites contributes directly to the maintenance of mechanical responsiveness, then agents which alter membrane binding of Ca++ (e.g. neomycin) may exert a stronger action on these highly reactive vessels. Thus, contractile responsiveness in peripheral arteries may depend upon depots of superficially bound Ca++ to a greater degree than in the more centrally located aorta.
Pulse Wave Transmission Times in Central Aorta and Peripheral Arteries in Normal Children
Authors: de Monchy C. , van der Hoeven G.M.A.
Published: September 2008

Pulse wave transmission times and pulse wave velocities in central aorta and peripheral arteries were measured in a group of 85 healthy children and adolescents between the ages of 1 and 21 years. A new external plethysmograph is described which gives reliable tracings of external pulsations. A method is given to calculate real pulse wave transmission time from the aortic valves to the groin.
Vascular Contraction: Effect of Age and Extracellular Calcium
Authors: Cohen Marlene L. , Berkowitz Barry A.
Published: September 2008

Contractile responses to norepinephrine, serotonin and potassium chloride were determined in vitro for aortas from rats 1, 2, 3 and 12 months of age. Responses were measured under conditions of optimum length (3 cm) and resting tension (1 g). Aortic response to a maximum concentration of norepinephrine was greatest for vessels from 3-month-old rats. For all three agonists, aortas from 12-month-old rats contracted less than aortas from 2-month-old rats. The role of calcium in aortic contraction also varied with age. For rats 1–2 months of age, serotonin and potassium chloride-induced contractions were highly dependent on extracellular calcium, while norepinephrine-induced contraction showed only a slight dependence on extracellular calcium. In 12-month-old rats, all agonists were dependent on extracellular calcium for contraction. For serotonin and norepinephrine, the ability of muscle to contract in calcium-free media was decreased with age. Although the mechanism for such an altered dependence of aortic contraction on calcium has not been established, it is proposed that the utilization of extracellular calcium for contraction is not only agonist- but also age-dependent.
Changes in the Contractile Response of Arteries and Veins from Hypertensive Rabbits to Sympathetic Nerve Activity: Assessment of Some Postsynaptic Influences
Authors: Bevan John A. , Bevan R.D. , Chang P.C. , Pegram B.L. , Purdy R.E. , Su Che
Published: September 2008

Contractile responses to field stimulation of intramural nerves of arteries and veins taken from rabbits made hypertensive by partial constriction of the abdominal aorta have been related to the carotid artery pressure. The increase in contraction of cephalic and short saphenous veins with rise in carotid artery pressure can be accounted for by an increase in sensitivity of the α-adrenergic receptor. The neurogenic contraction of the ear artery increased with carotid artery pressure rise. Changes in some of the extraneuronal factors that influence transmitter distribution and disposition in the tunica media were examined. In hypertensive animals, the percentage of released adrenergic transmitter entering the vessel wall might be expected to decrease due to an increase in medial thickness. However, this percentage was not significantly altered in the ear artery probably due, in part, to a concomitant increase in medial permeablity to the transmitter. Extraneuronal transmitter disposition factors, i.e. extraneuronal uptake, monoamine oxidase, and catechol-O-methyltransferase activity are directly related to the wet weight of the vessel wall. Thus, their contribution to transmitter disposition would be expected to increase with increase in vessel wall thickness and tend to reduce the response to sympathetic activity. As the contractile response increased in the hypertensive vessels
Mechanism of Potassium Relaxation of Arterial Muscle
Authors: Bonaccorsi A. , Hermsmeyer K. , Aprigliano O. , Smith C.B. , Bohr D.F.
Published: September 2008

Strips of arterial muscle were prepared from rat tail and femoral arteries and dog mesenteric arteries. All muscles developed a contracture slowly when exposed to a potassium-free solution, but relaxed rapidly when potassium was added to the bath to give a concentration as low as 0.1 mM. The slow contracture is caused by norepinephrine release from intrinsic nerve endings, but the rapid relaxation occurs while the norepinephrine concentration is still high. Contractions produced by exogenous norepinephrine or serotonin in a potassium-free bath were also made to relax by the addition of potassium. After several minutes these relaxations reversed abruptly and spontaneously to return to their original level of contraction. The rapid relaxation was found to be due to an electrogenic transport mechanism which caused hyperpolarization within several seconds after the addition of potassium. This hyperpolarization is believed to be caused by electrogenic ion transport since it exceeded the expected membrane potential based on the potential calculated from potassium concentrations, ER. Hyperpolarization declined within 5–15 min, allowing contraction to redevelop. Ouabain was found to prevent both the 1 Supported by USPHS NIH grants HL-03756, HL-14388, HL-16328, and NS-10558. 2 Recipient of Research Career Development award HL-00073 from the National Institutes of Health.
Arterial Pressure Development in Neonatal and Young Spontaneously Hypertensive Rats
Authors: Lais L.T. , Rios L.L. , Boutelle S. , DiBona G.F. , Brody M.J.
Published: September 2008

Systemic arterial pressures of spontaneously hypertensive rats (SHR) were not detectably different from control rats prior to 3 weeks of age. Arterial pressure was elevated in SHR at 4 weeks compared to Wistar-Kyoto rats. Thus, the term ‘prehypertensive stage’ should probably be reserved for animals less than 1 month of age when this model is examined.
Influence of Desipramine on the Uptake and Efflux of Radiolabelled Bretylium and Bethanidine in the Adventitial and Media-Intimal Layers of Rabbit Aortic Strips
Authors: Eckhardt Batmanglidj , Maxwell R.A. , Copp F.C.
Published: September 2008

The desipramine-sensitive uptake (neuronal uptake) of 14C-bretylium and 14C-bethanidine into the rabbit aortic adventitial layer from 3 × 10–6 m solutions increased with time during a 20 min incubation. For both compounds a neuronal uptake of 50 pmol/50 mg wet weight adventitia was associated with 10% block of the contractile response to field stimulation at 16 Hz and 150 pmol/50 mg with 60% block. The concentration of blocking agents inside the neuron at 50% blockade was calculated to be 260 × 10–6 M, an 87-fold increase over the medium. The bretylium in the neuron decreased by 50% during 20 min washout, and bethanidine by 29%. Desipramine when added to the bath 20 min following the addition of the blocking agents led to a loss of bretylium but not of bethanidine from the adventitia. Desipramine had little or no effect on the uptake, washout or disposition of either blocking agent in the media-intimal layers. The data indicate that bretylium has a greater propensity than bethanidine to be lost from the neurons; however, it appears to be recycled back through the membrane via the amine pump more readily than bethanidine. The fact that conservative calculations indicate that the neuronal membrane slowly establishes a concentration of the blocking agents within the neuron that is known to produce rapid local anesthesia when topically applied to adrenergic nerve trunks and which approaches a concentration needed to inhibit sensory endings suggests that local anesthesia may play a role in the mechanism of neuron blockade.
Effects of Chronic Nicotine Administration on RBC Velocity in Mesenteric Capillaries of the Rat
Authors: Richardson Daniel , Morton Robert , Howard Jck
Published: September 2008

The purpose of this study was to determine the effects of chronic administration of nicotine on red blood cell (RBC) velocity in single capillaries of the mesentery. Ten male rats consumed an average of 2.38 mg nicotine/kg/day, an approximate ‘2 pack’ equivalent, in their drinking water for a period of 15–20 weeks. At the end of this time RBC velocity was measured in single capillaries of the mesentery. The data were compared to RBC velocities measured in a group of matched control rats. Red cell velocities in the control and nicotine groups averaged 1.22 ± 0.23 and 0.59 ± 0.10 mm/sec SEM, respectively. These values were significantly different (p < 0.01). It is concluded that chronic administration of nicotine to rats in levels equivalent to tobacco smoking reduces resting capillary blood flow in the mesenteric circulation as indicated by differences in erythrocyte velocity.
Effect of Atropine on Vascular Adrenergic Neuroeffector Transmission
Authors: Nedergaard Ove A. , Schrold Jørgen
Published: September 2008

Atropine, homatropine, scopolamine, procaine, lidocaine and phentolamine inhibited the contractile response of rabbit isolated pulmonary artery elicited by electrical-field stimulation. Methylatropine had no effect. The inhibition induced by atropine (2 × 10–6–2 × 10–4 m) had a rapid onset of action and then remained almost constant. The inhibition was slowly reversible. The potency of atropine as an inhibitor of responses to field stimulation was very much less than the potency of phentolamine. The inhibition was not antagonized by cocaine or (+)-amphetamine. Atropine (3 × 10–5 and 3 × 10–4 m) enhanced the electrical-field-stimulation-induced outflow of tritium from the pulmonary artery preloaded with 3H-(–)-noradrenaline. In contrast, atropine in a concentration-dependent manner either had no effect or slightly decreased the tyramine-induced outflow of tritium. Atropine reduced the contractile response of the pulmonary artery evoked by tyramine. Atropine (10–4 and 3 × 10–4 m) and phentolamine inhibited the arterial contractions elicited by exogenous (–)-noradrenaline in an apparently competitive manner. The contractions of rabbit isolated aorta elicited by (–)-noradrenaline, serotonin and histamine were inhibited by atropine (10–5 and 10–4 m). Atropine was very much less potent in antagonizing noradrenaline, histamine and serotonin than in antagonizing acetylcholine. The inhibitory potency of atropine, procaine and lidocaine on the accumulation of 3H-(–)-noradrenaline by rabbit aorta in vitro was much less than that of cocaine. The relationship between the aortic concentration of 3H-atropine and in vitro accumulation was almost linear. The accumulation was slightly higher at37 °C than at 1 °C. The results suggest that atropine blocks α-adrenoceptors, both presynaptically at the adrenergic neurone terminals and postsynaptically at the smooth muscle. In addition, atropine may possibly act in a nonspecific manner at postsynaptic sites.
Differential Responses to Transmural Stimulation and Vasopressin in Isolated Strips of Artery and Vein of Human Mesoappendix
Authors: Wyse George
Published: September 2008

Responses to exogenous norepinephrine (NE), transmural electrical stimulation, 5-hydroxytryρtamine (5-HT) and lysine vasopressin were studied in isolated helical strips of the small artery and vein from the mesoappendix of patients undergoing incidental appendectomy at the time of cholecystectomy. Responses to NE and 5-HT were similar in each vessel. Arterial strips were unresponsive to electrical stimulation and responses to vasopressin were greater than those to NE in this tissue. Venous strips were unresponsive to vasopressin. Relaxation of exogenous NE responses following oil immersion of arterial strips was unaffected by cocaine whereas relaxation of similarly treated venous strips was markedly prolonged. The data suggest: (1) that the artery of human mesoappendix is poorly innervated and (2) that vasopressin is clearly more active on human mesoappendix artery than it is on human mesoappendix vein. The latter observation may help to explain the efficacy of vasopressin infusion in gastrointestinal hemorrhage secondary to portal hypertension.
Reactivity of Isolated Human Cerebral Arteries to Biogenic Amines
Authors: Shibata Shoji , Cheng John B. , Murakami Wilson
Published: September 2008

Serotonin (5-HT), histamine, norepinephrine, methoxamine and isoproterenol caused dose-dependent contraction of human cerebral arteries. The potency of 5-HT was greater among test agents in the basilar arteries, whereas it was equivalent to that of norepinephrine in human anterior, middle and posterior cerebral arteries. Acetylcholine and carbachol (10–9–10–5 M) caused a negligible response in human cerebral arteries. Contractile response to 5-HT was greater in the distal rather than middle portion of the human basilar arteries while this order was reversed in the response to norepinephrine. Tyramine (10–4 M) caused tonic contraction and nicotine (10–4 M) and electrical transmural stimulation produced phasic contraction of arteries which were antagonized by adrenergic blocking agents. Adenine nucleotides failed to cause relaxation and only high concentration of adenosine caused a minute relaxation. However, papaverine and nitroglycerin caused marked relaxation. These results suggest that adrenergic mechanism may play a role in the regulation of vascular tone in human cerebral arteries.
Mechanisms Underlying Overshoot Dilation after Sympathetic Denervation
Authors: Gero J. , Gerová M.
Published: September 2008

(1) 30–60 sec after transection of the sympathetic chain, the diameter of both femoral artery and vein dilates to approximately 120% of the control diameter (‘overshoot dilation’). Vessel diameter subsequently decreases and stabilizes with 5–10 min at a value of 108% of the original (‘stabilized dilation’). (2) After treatment with norepinephrine-uptake-blocking drugs (cocaine, imipramine), the transient overshoot dilation is abolished and the diameter 1 min after denervation is identical to that at stabilized dilation. (3) It is proposed that (a) the stabilized rather than the transient overshoot dilation represents the loss of sympathetic control following denervation and (b) the overshoot dilation reflects a transient decrease in transmitter concentration within the vessel wall, associated with a temporarily undiminished rate of neural reuptake activity persisting even in the absence of transmitter release.
In vivo Study of Microvascular Wall Characteristics and Resting Control in Young and Mature Spontaneously Hypertensive Rats
Authors: Bohlen Glenn , Lobach David
Published: September 2008

This study was designed to determine if vessel wall hypertrophy and increased expression of sympathetic activity occur in the microcirculation during the development of hypertension. The cremaster muscle microvasculature of normal Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats was observed at age 5–7 weeks and 16–18 weeks. For age-matched WKY and SHR rats, the diameters, wall thicknesses and vessel wall cross-sectional areas for the majority of comparable types of arterioles were not significantly (p > 0.05) different. After denervation of the cremasteric muscle, the large and intermediate diameter arterioles of young WKY rats dilated significantly (p < 0.05) more than did comparable vessels of SHR rats. In contrast, the dilation of comparable types of arterioles in mature WKY and SHR rats following denervation was not significantly (p > 0.05) different. The results do not support either abnormal vessel wall hypertrophy, vasoconstriction or increased expression of sympathetic activity in SHR rats compared to WKY rats up to age 16–18 weeks.
Systemic and Regional Flow Distribution in Normotensive and Spontaneously Hypertensive Young Rats Subjected to Lifetime β-Adrenergic Receptor Blockade
Authors: Nishiyama Keisuke , Nishiyama Aiko , Pfeffer Marc A. , Frohlich Edward D.
Published: September 2008

To determine quantitatively organ blood flow distribution as the result of lifelong β-adrenergic receptor blockade, 23 and 24 normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, respectively, were treated from conception with tap water (control; 10 WKY and 8 SHR), propranolol (0.5 mg/ ml drinking water; 6 WKY and 8 SHR), or timolol (0.5 mg/ml drinking water; 7 WKY and 8 SHR) via placental circulation, mothers’ milk, and drinking water. At 12 weeks of age all six groups were studied hemodynamically under ether anesthesia using an electromagnetic flowmeter and radioactive carbonized (15 µm) microspheres. Untreated SHR demonstrated normal cardiac output (CO) and CO distribution to all organs except for myocardium and testes, thereby confirming our previous work. With either propranolol or timolol treatment the course of development and maintenance of arterial pressure was no different than the pure-tap-water-fed WKY and SHR despite an approximate 30% reduction in CO. Further, with both β-receptor antagonists CO distribution was significantly reduced to skeletal muscle (p < 0.001), unchanged to the heart, and increased (p < 0.05) to the remaining organs (including kidneys and brain) in both groups. Thus, as a result of
The Innervation of the Rabbit Ear Artery
Authors: Hume W.R. , Waterson J.G.
Published: September 2008

An examination of sections of the central artery of the rabbit external ear with the transmission electron microscope revealed a single and uniform population of axons near the medial-adventitial border. The dimensions of the neuromuscular cleft (mean closest distance 0.5 µm) and of the approaches between smooth muscle cells (not less than 20 nm) were determined. On the basis of the morphology of the neuronal vesicles and their ability to take up 5-hydroxydopamine the axons were classified as adrenergic, confirming previous light-microscopic histochemical observations. The axons also exhibited a weak but definite acetylcholinesterase activity in association with their axon membrane, as shown by a histochemical technique.
Responses to Adenine Nucleotides and Related Compounds of Isolated Dog Cerebral, Coronary and Mesenteric Arteries
Authors: Toda Noboru , Okunishi Hideki , Taniyama Kohtaro , Miyazaki Mizuo
Published: September 2008

In helically cut strips of dog cerebral, coronary and mesenteric arteries contracted with prostaglandin F2α, adenosine, AMP, ADP, ATP and cyclic AMP produced dose-related, persistent relaxation. On the basis of ED50s, the relaxant effect seen in cerebral arteries was in the order of AMP, ADP, ATP > adenosine, cyclic AMP > adenine, dibutyryl cyclic AMP > inosine. On the basis of maximum relaxations, the effect was in the order of adenine, dibutyryl cyclic AMP ≧ adenosine, AMP, ADP, ATP > cyclic AMP, inosine. The relaxant responses to adenosine, AMP, ADP, ATP and cyclic AMP were attenuated by treatment with aminophylline, whereas the relaxations induced by dibutyryl cyclic AMP, adenine and inosine were not altered. It is concluded that adenosine, AMP, ADP and ATP, but not adenine and inosine, appear to share receptors underlying arterial relaxations, and the cyclic AMP-induced relaxation does not derive from increments in cellular cyclic AMP. Treatment with aspirin did not alter the relaxant effect of ADP, adenosine and adenine, suggesting that the release of vasoactive prostaglandins is not involved.
Abnormal Biochemistry of Subcellular Membranes Isolated from Nonvascular Smooth Muscles of Spontaneously Hypertensive Rats
Authors: Kwan C.Y. , Grover A.K. , Sakai Y.
Published: September 2008

Microsomal fractions enriched in plasma membranes and endoplasmic reticulum were isolated from stomach fundus and vas deferens from age-matched Okamoto spontaneously hypertensive (SHR) rats and corresponding Kyoto-Wistar normotensive rats (KWR). Alterations of several enzyme activities and Ca2+ accumulation of the isolated microsomal fraction from these nonvascular smooth muscles provide direct evidence of abnormal smooth muscle membrane biochemistry in SHR. Decreased Ca2+ accumulation in the presence of but not in the absence of adenosine triphosphate by the microsomal fractions of both fundus and vas deferens from SHR is consistent with previous findings using plasma membranes from vascular smooth muscles from SHR and cannot be explained in terms of adaptation induced by elevation of blood pressure in SHR. Defective Ca2+ handling now observed in both vascular and nonvascular smooth muscles from hypertensive animals not only provides a cellular basis for the altered reactivity and contractility of smooth muscles observed in SHR, but also supports the hypothesis that spontaneous hypertension is associated with a generalized widespread alteration in smooth muscle membrane fraction.
Pattern and Innervation of Pial Microvascular Effectors Which Control Blood Supply to Cerebral Cortex
Authors: Baramidze D.G. , Reidler R.M. , Gadamski R. , Mchedlishvili G.I.
Published: September 2008

In experiments with adult rabbits the active microvascular segments located at particular sites of the minor pial arterial ramifications were investigated. These appeared as sphincters at off-shoots of the arterial branches, the precortical arteries, and the arterial microanastomoses. The sphincters and the precortical arteries were found plentifully supplied with the cholinergic and adrenergic nerves, but the innervation of the microanastomoses was not considerably different from that of the adjacent arterial branches. The nerves of the precortical arteries were in direct connection with the nerve fibers of the arterial branches located inside the cerebral cortex. The pattern of distribution and innervation of the active vascular portions in pial microvascular bed suggests the probability of a neurogenic control of the blood supply to the smallest areas of the cerebral cortex.