Changes in the walls of autologous venous grafts after transplantation into arteries

In 54 dogs 76 operations on plastics of the common carotid arteries with the femoral vein segments have been performed. The animals have been observed for 3 days--1.5 years. The grafts, preserving their permeability, have been studied using a complex of anatomical, histological and micromorphometric techniques. At early stages after the operation (up to 7 days), dystrophic and necrobiotic changes predominate in the wall of the venous graft. As a result of overstretching of the denervated and devascularized vessel, under the effect of a high arterial pressure, nearly total rejection of the endothelial lining takes place, as well as death of some smooth myocytes in the middle tunic; this determines appearance of early thromboses. During 2-6 months after the operation, against the background of a good revascularization of the graft, restorative and adaptive changes develop in its wall. The intima becomes thick at the expense of formation of the obliquely situating layer of myocytes, as well as the result of parietal thromboses organizing on the deendothelized internal surface. These thickenings are especially well seen in the zones of anastomoses. In 6 months--1.5 years after the transplantation into the artery, as a result of constriction of the vessels feeding the graft and reduction of blood stream along them, atrophic and sclerotic changes increase in the wall. The intimal thickenings often acquire the pattern of fibrous patches, that make the lumen more narrow; this can cause appearance of late occlusions and thromboses of the grafts.     

Baroreflexes originated in vertebral artery zones upon peripheral vein tonus, systemic arterial blood pressure, and external respiration

The investigation was intended to study the role ofbaroreceptors ofhemodynamically isolated zone of vertebral arteries in regulation of peripheral veins tonus, arterial pressure and external respiration. Pressure decrease in this vascular reflexogenic zone led to reflex responses of increase in femoral vein tonus, elevation of blood pressure level and stimulation of external respiration. The opposite reflex responses of cardio-respiratory functional system to initial pressure activation of vertebral arteries baroreceptors are observed. Basing on generalization of our own findings and similar physiological and morphological researches of other authors, it is established that afferentation from the vertebral artery zone is a reflexogenic factor of somatic muscles' veins tonus regulation. These reflexes of capacity vessels tonic activity changes are part of cardio-respiratory responses of maintaining the tissue gaseous exchange.     

The ultrastructure of peripheral arteries during the development of DOCA hypertension in the rat

Summary The ultrastructure of the unconstricted superficial epigastric and femoral arteries is described in normal rats and in animals with hypertension induced by unilateral nephrectomy, by subcutaneous injections of desoxycorticosterone acetate and drinking of 1% NaCl. The femoral artery showed by far the greater response to the DOCA-saline treatment. In both vessels, the smooth-muscle cells changed from the normal spindle shape to a blunt ended outline with numerous pinocytotic vesicles and prolific collagen production. With long term hypertension, particularly in the femoral artery, the smooth-muscle cell profiles became very irregular. Hypertrophy of the organelles of the smooth-muscle cells was associated with an increase in the intercellular material which gradually changed from a mainly collagenous character to mainly vesicular. Lysosomal activity indicated cell disintegration. White blood cells adhere to the endothelium in hypertensive rats and there was an increase in subendothelial material. The number of intimal smooth-muscle cells increased noticeably in the femoral artery. In both arteries, the adventitial fibroblasts hypertrophied in hypertensive rats. In animals with an elevated blood pressure the morphological response was observed as early as 4 to 7 days after initiation of treatment.This work was supported by grants from the British Columbia Heart Foundation and the Medical Research Council of Canada.The authors are indebted to Miyoshi Nakashima for her invaluable assistance with these experiments.     

Sources of the innervation of the carotid reflexogenic zone in representative reptiles

The investigation is dedicated to study sources of the carotid reflexogenic zone innervation in 43 tortoises (Testudo horsfieldi and Emys orbicularis). In 7 tortoises fine preparation of the vessels and nerves of the cervical area after V. P. Vorob'ev has been performed. In 13 animals descending branch of the glossopharyngeal nerve has been resected. In 4--the caudal ganglion of this nerve and in 9 tortoises the caudal ganglion of the vagus nerve have been resected. In 10 tortoises adrenergic nervous plexuses are studied after Falck-Govyrin method, and cholinergic ones--after Karnovsky-Roots. As demonstrate anatomical investigations, to the carotid reflexogenic zone of the tortoises, situating in the area of the common carotid artery base, the branches of the glossopharyngeal and of the vagus nerve approach. The experiments with resection of these nervous conductors demonstrate that by the end of 3 days after the operation myelin nervous fibers of various thickness are at the stage of granular decay. Cholinergic and adrenergic nervous fibers and plexuses are revealed histochemically in the carotid zone.     

Comparison of Invasive Blood Pressure Measurements from the Caudal Ventral Artery and the Femoral Artery in Male Adult SD and Wistar Rats

Background and Purpose

Studies have suggested that the caudal ventral artery is a potential site for continuous arterial blood pressure monitoring in rats. However, the agreement of mean arterial pressure values between the femoral artery and the caudal ventral artery has not been investigated. This study was performed to identify whether the caudal ventral artery could be safely used for continuous blood pressure monitoring as an alternative site to the femoral artery.

Methods

Rats were randomized into four groups: Sprague Dawley rats under normothermia; Wistar rats under normothermia; Sprague Dawley rats under hypothermia; Wistar rats under hypothermia. Each rat underwent simultaneous monitoring of blood pressure using femoral artery and caudal ventral artery catheterization during a stable hemodynamic state and three periods of acute severe hemodynamic changes. The effects of rat strain, rectal temperature, experimental time course and hemodynamic factors on pressure gradients, the concordance of mean arterial pressure values between the femoral artery and the caudal ventral artery, and the rates of distal ischemia after surgery were determined.

Results

There was a significant difference in the rate of distal ischemia between femoral and caudal ventral arteries after catheterization (25% vs 5%, P<0.05). The overall mean gradient and the mean gradient under a steady hemodynamic state were 4.9±3.7 mm Hg and 5.5±2.5 mm Hg, respectively. The limits of agreement (bias±1.96 SD) were (−2.5 mm Hg, 12.3 mm Hg) and (-0.5 mm Hg, 10.5 mm Hg), respectively. Although the concordance decreased during the first 30 sec of each period of severe hemodynamic changes, the degree of agreement was acceptable regardless of the effects of rat strain and rectal temperature.

Conclusions

Based on the degree of agreement and the safety of catheterization, the caudal ventral artery may be a preferred site for continuous arterial blood pressure monitoring without acute severe hemodynamic changes.     

Characteristics of development of collateral vessels after experimental ligation of the femoral artery under conditions of venous insufficiency

Isolated ligation of the femoral artery and its combined ligation with the vein was performed in experiments on 62 dogs. Anatomical and physiological methods were used. It was stated that at the combined ligation collaterals developed sooner, number of anastomoses in muscles of the femoral posterior osseous-fascial case was greater, and their lumen was wider than at the isolated ligation of the femoral artery. However, the combined arterio-venous insufficiency was followed by a more severe postoperative course and noticeable biochemical disturbances. Thus, a certain discrepancy between the development of collaterals and the function of the tissue they feed was revealed. Analysing the data obtained it is possible to conclude that venous insufficiency, despite accelerating the transformation of the collaterals as a whole, aggravates conditions for collateral arterial circulation in the extremity.     

Distally based vastus lateralis muscle flap for coverage of wounds about the knee

The blood supply to the vastus lateralis muscle has been evaluated by dye injection techniques in fresh cadaver dissections. The main dominant blood supply is the descending branch of the lateral femoral circumflex artery. Vascular contributions from distal perforators of the superficial femoral artery, the superior geniculate artery, fill the main vascular pedicle in a retrograde fashion. Latex staining is observed consistently in the proximal third of the muscle. Five patients are presented in whom the distally based vastus lateralis muscle flap was successfully used to cover defects above the knee. Superficial muscle necrosis is a complication of this operation but has not precluded its usefulness. It is anticipated that this flap will be useful in the armamentarium of reconstructive surgeons treating such problematic patients.     

Systemic circulatory effects of pentagastrin

Effects of pentagastrin on systemic circulation were studied in anesthetized cats. Systemic arterial, central venous and portal pressure were monitored with electromanometers and blood flow through the superior mesenteric artery, common carotid artery, femoral artery and ascending aorta were measured with an electromagnetic blood flow meter. Pentagastrin injected intravenously at a doses of 2.0, 4.0 and 8.0 micrograms/kg induced a dose-dependent fall in arterial pressure, heart rate and cardiac output, increased mesenteric blood flow, decreased common carotid artery blood flow, did not change femoral artery blood flow and slightly rose central venous pressure. Atropine blocked observed effects. After repeated injections of the peptide, tachyphylaxis quickly developed. The obtained results indicate that pentagastrin influences general hemodynamics probably via interaction with cholinergic receptors.     

Identification of differentially expressed genes like cofilin2 in growing collateral arteries

Arteriogenesis, the growth of pre-existing collateral arteries, can be induced in rabbits by occlusion of the femoral artery. In order to analyze the differential gene expression in arteriogenesis, cDNA of collateral arteries 24h after femoral occlusion or sham operation was subjected to suppression subtractive hybridization (SSH). We demonstrated an upregulation of the U6 snRNA binding protein Lsm5, cytochrome b, an expressed sequence tag, and the actin-depolymerizing factor cofilin2 mRNA in collateral arteries 24h after femoral ligation. For cofilin2, we also detected an increase in the protein level and a localization predominantly in smooth muscle cells of collaterals. Simultaneously with the upregulation of cofilin2 we found a downregulation of the alpha-smooth muscle actin mRNA in growing collateral arteries. In summary, our data showed an augmented expression level of genes contributing to different fundamental processes of arteriogenesis.     

Morphofunctional reorganization of the kidneys in lymphatic outflow disturbance

In 115 Wistar male rats structures and rates of tissue blood flow have been studied in the cortical and medullary renal substance histologically, polarographically (estimation of the volumetric tissue blood flow by hydrogen clearance). Systemic arterial (peritoneal aorta), venous (caudal vena cava) and lymphatic (renal lymph nodes) pressures have been measured, normal and after ligation of the thoracic duct at early (1-3 days), middle (1 month) and late (2-3 months) periods. In 1-3 days edema and dystrophy of the renal parenchyma, decrease of the blood flow rate in the cortical and its increase in the renal medullary substance, as well as a sharp elevation of pressure in the lymph nodes are observed. In 1 month of the experiment together with dystrophy and edema moderate sclerosis, decreasing blood flow rate in the cortical and medullary substance are noted. Increase of the systemic arterial and venous pressure and decreasing pressure in the lymph nodes, as well as a sharp increase of the renal nodes mass are revealed. In 2-3 months of the experiment, together with sclerosis of the renal parenchyma, elevated blood flow rate is observed in the kidneys and decreasing pressure in the lymph nodes up to its initial value takes place.     

Ultrastructural organization of endings of the efferent fibers of zones A1 and A4 of the auditory cortex of the cat in the superior olivary complex

Distribution of synapses formed by straight corticofugal fibers running from the zone A1 and A4 of the acoustic cortex in the main basilar nuclei of the cat superior olive has been studied electron microscopically. These synapses are presented as axodendritic structures situating on processes of small and middle diameters, predominantly at the side of the operation (both in the medial and lateral complexes). Problems on functional influence of the acoustic cortex projections on subcortical acoustic centers depending on the form and amount of the synaptic terminals are discussed.     

Formation of the muscular and neural components of the femoral artery wall of the dog in early postnatal ontogeny (an ultrastructural and histochemical study)

In puppies of various age (newborn, 2-week-old. 1- and 3-month-old) formation of smooth muscle and neural components in the femoral artery wall has been studied electron microscopically and histochemically. As demonstrate the electron microscopic data, the femoral artery wall is mainly formed by birth, nevertheless, structural components of its each tunic are at various stage of maturation and only by the 3d month the differentiation and specialization process of all cellular elements is fully completed. Owing to a combination of techniques used, it has been possible to follow the dynamics in formation of the innervation apparatus of the femoral artery. In the newborn animals the adrenergic apparatus of the femoral artery is presented mainly as thick fibers of a cable type; they form a plexus with loose loops at the periphery of the external tunic. Varicosities are scanty. By the 3d month there is a well developed network of the adrenergic fibers at the border of the middle and external vascular tunics. Some terminals penetrate into the muscular tunic. There is a great number of varicosities in the neural fiber axons. At the border of the middle and external tunics of the vessel, complex neuro-muscular interrelations are forming with an aim to bring functionally closer the main structural components of the wall. In the course of the early postnatal ontogenesis in dogs up to 3 months of age, in the femoral artery wall certain processes take place directed to ensure the neuroregulatory vasomotor properties of the vessel.     

Hemodynamic response to LBNP during the 14 month MIR spaceflight (94-95)

Lower body negative pressure (LBNP) was used during the Mir spaceflight in a study of orthostatic tolerance. Hemodynamic responses were measured including heart rate, blood pressure, cerebral artery blood flow, and lower limb vascular resistance. Results showed that femoral flow volume decreased, which may be due to hypovolemia and reduced cardiac output. Additional changes in femoral vascular response and cerebral to femoral blood flow are discussed.     

Bronchial collateral vessel micropuncture pressure in postobstructive pulmonary vasculopathy.

Postobstructive pulmonary vasculopathy, produced by chronic ligation of one pulmonary artery, markedly increases bronchial blood flow. Previously, using arterial and venous occlusion, we determined that bronchial collaterals enter the pulmonary circuit at the distal end of the arterial segment. In this study, we tested the hypothesis that pressure in bronchial collaterals (Pbr) closely approximates that at the downstream end of the arterial segment (Pao). We pump perfused [111 +/- 10 (SE) ml/min] left lower lobes of seven open-chest live dogs 3-15 mo after ligation of the left main pulmonary artery. Bronchial blood flow was 122 +/- 16 ml/min. We measured pulmonary arterial and venous pressures and, by arterial and venous occlusion, respectively, Pao and the pressure at the upstream end of the venous segment (Pvo). Pbr was obtained by micropuncture of 34 pleural surface bronchial vessels 201 +/- 16 microns in diameter. We found that Pbr (14.4 +/- 1.0 mmHg) was similar to Pao (15.0 +/- 0.8 mmHg) but differed significantly (P < 0.01) from Pvo (11.3 +/- 0.5 mmHg). In addition, Pbr was independent of systemic arterial pressure and bronchial vessel diameter. Light and electron microscopy revealed that, in the lobes with the ligated pulmonary artery, the new bronchial collaterals entered the thickened pleura from the parenchyma via either bronchovascular bundles or interlobular septa and had sparsely muscularized walls. We conclude that, in postobstructive pulmonary vasculopathy, bronchial collateral pressure measured by micropuncture is very close to the pressure in precapillary pulmonary arteries and that most of the pressure drop in the bronchial collaterals occurs in vessels > 350 microns in diameter.     

Changes in hemodynamics of tibial diaphysis in case of blood flow disorder in superficial femoral artery

Changes in tibial hemodynamics have been studied experimentally after applying a clamp (n=41) and resection of superficial femoral artery (n=22) in 63 adult dogs. It has been revealed with the help ofrheovasography that, in case of blood flow disorders in the superficial femoral artery, anastomoses with deep femoral artery branches contribute to maintenance of blood circulation in tibia, and in this connection the parameters of tibial blood flow may significantly differe from those of circulation in the leg soft tissues. Preservation of intraosseous pressure all along tibial diaphyseal cavity demonstrates a possibility of using its driving force to compensate for the circulatory insufficiency in the leg soft tissues and, moreover, in that part of the bone the environment of which in ischemia is involved.     

Evaluation of Compliance of Arterial Vessel Using Coupled Fluid Structure Interaction Analysis

The in vivo and ex vivo compliance of arteries are expected to be closely related and estimated. Fluid-structure interaction analysis can assess the agreement between the two compliances. To evaluate this hypothesis, a pulsatile fluid-structure interaction analysis of blood flow in femoral artery of a dog was conducted using: (1) measured in vivo mean pressure (72.5 mmHg), mean pressure drop (0.59 mmHg), mean velocity (15.1 cm/sec); and (2) ex vivo measurements of non -- linear elastic properties of femoral artery. Additional analyses were conducted for physiological pressures (104.1 and 140.7 mmHg) and blood flow using a characteristic linear pressure -- flow relationship. The computed compliance decreased from 0.198% diameter change/mmHg at 72.5 mmHg to 0.145% diameter change/mmHg at 140.7 mmHg. The computed compliance tends to match well with in vivo compliance of femoral artery at lower pressure but is overestimated at higher pressure. This suggests an alteration in the compliance of the artery during ex vivo elasticity measurements.     

Central mediated pressor effect by prostaglandins in the rat

Extremely small concentrations (1 ng/kg/min) of prostaglandins E₁, A₁, and A₂ elevated arterial blood pressure in the rat when infused into the carotid artery. Similar infusions into the femoral vein failed to demonstrate a pressor response. Higher concentrations of the same prostaglandins infused into the femoral vein resulted in a significant depression of blood pressure.     

Plasma angiotensin-converting enzyme activity and blood pressure during the first year of life in normotensive and spontaneously hypertensive rat.

Plasma angiotensin-converting enzyme (ACE) activity and systolic blood pressure were studied every consecutive month during the first years of life in male spontaneously hypertensive (SHR) and in normotensive rats (NWR). During the first month after birth neither ACE activity nor systolic blood pressure showed significant difference between SHR and NWR. ACE activity in SHR was significantly reduced from 2nd till 12th month of age in comparison with age-matched NWR. In the 2nd month of age the systolic blood pressure was significantly higher in SHR than in NWR, it increased further until the 5th month and was maintained at this high level till the 12th month. No correlation between changes in the systolic blood pressure and the ACE activity was found in SHR after the 2nd month of age. During the investigation period no age-related dynamics of ACE activity was observed in SHR. The observed difference of ACE activity was not due to an increase of plasma his-leu hydrolyzing activity in SHR and was not abolished after a 24-hour dialysis of plasma. This difference could not be caused by the altered effect of chloride ion on the enzyme since similar pattern of Cl-dependent activation of plasma ACE in 4-month-old SHR and NWR was observed. Lineweaver-Burke plot analysis revealed that this difference appears to be due to a decrease of the enzyme maximal velocity in SHR but to a change of the Km value of ACE for the substrate hippuryl-1-his-1-leu. Our data provide evidence for a lower concentration of the available active enzyme molecules in SHR plasma in respect to NWR after the 1st month of life. Whether the reduced ACE activity in SHR is a consequence of the increased blood pressure remains to be elucidated.     

Lymphocyte-induced angiogenesis: a morphometric study in the chick embryo chorioallantoic membrane.

A morphometric analysis was carried out on the chorioallantoic membrane (CAM) vasculature in chicken embryos treated (1) with phytohemagglutinin (PHA), (2) with supernatants of cell cultures of normal human T lymphocytes and (3) of T lymphocytes stimulated with PHA in order to evaluate their angiogenic properties. In the left chorioallantoic artery, the number of primary collaterals, and the number and length of secondary and tertiary collaterals were measured. In the series treated applying procedures 1 and 3, the mean value of the total number of all the collaterals was higher than that of the normal-developing CAM vessels, while the length of the secondary and tertiary collaterals was lower than that of the normal-developing blood vessels. In the series treated following procedure 2, no statistically significant differences were observed between experimental and control series in any parameters evaluated. The possible significances of these morphological findings are discussed with reference to the angiogenic roles played by human T lymphocytes, probably determined by lymphokines released after the activation of these cells by PHA, and by PHA alone, probably dependent on its aspecific mitotic activity.