Walls Of Blood Capillaries Research Articles

The endoendothelial fibrin lining as the crucial barrier and the role of fibrin(ogenin) gels in controlling transcapillary transport.

The interface between the two portions of the 'vessel-blood organ', viz., the vessel wall and the circulating blood, is considered by the author to be the endoendothelial fibrin lining (EEFL). The view that the endothelium, consisting of the endothelial cells and the interendothelial cement substance, is the primary filtration barrier in capillary permeability (CP) is no longer tenable. There is considerable evidence that the primary barrier is an endocapillary protein layer, originally postulated by Danielli in 1940. Copley considered this layer to be identical with the EEFL formed in the more or less immobile portion of the plasmatic zone in close proximity to the vessel wall. Processes of fibrin formation and fibrinolysis can occur there homeostatically, undisturbed by the flow of blood. The fibrinopeptides and plasminopeptides, freed at this site by the conversion of fibrinogen to fibrin and of plasminogen to plasmin, respectively, were reported by Copley et al in 1966 to augment CP. These peptides thus take part in the steadily occurring normal physiological CP. This is facilitated by the porosity of the EEFL due to the network or gel structure of fibrin strands. The author's concept that the EEFL acts as the primary barrier, controlling transendothelial transport and transport across the basement membrane (BM), is discussed on the basis of older and recent findings by several investigators. In particular, the BM is dealt with in some detail as a barrier. Emphasis is placed on the existence of fibrin as a main constituent of the BM, hitherto not generally known. This was demonstrated by direct evidence in the production of (non-thrombocytopenic) vascular purpura with fibrin antiserum. Numerous tiny foci of fibrin(ogenin) gels are expected to stud the BM. Augmented capillary fragility (CF) due to increased fibrinolysis of many of these focal fibrin gels result in petechial hemorrhages. CF and CP are physical properties of the blood capillary wall which behave antagonistically and are controlled by fibrin formation and fibrinolysis, steadily occurring in the vascular layers including the BM. This barrier secures the integrity of the capillary wall by preventing extravasation of blood or hemorrhages. New experimental approaches to verify the detection of fibrin in the microstructure of the capillary wall are proposed. Moreover, hemorheological experimentation, models and treatments are needed to establish whether or not the EEFL is the crucial, critical barrier in CP, as proposed.

Ultrastructural localization of phosphatases in the rat parathyroid gland.

Ultrastructural localizations of phosphatases were observed in the rat parathyroid gland. Activities of alkaline phosphatase and adenosine triphosphatase were found on the caveolae or pinocytotic vesicles of the capillary endothelia. In the parenchymal cells, they were demonstrated to be stronger both at the plasma membranes facing the pericapillary space and at their transitional portions to the lateral plasma membranes than at the remaining lateral plasma membranes including microvilli. Activities of thiamine pyrophosphatase and inosine diphosphatase were detected on one or two layers of lamellae at the inner face of the Golgi apparatus, and the localization of the latter enzyme was more restricted than that of the former. Additionally, they were sometimes observed also on the blood capillary wall. Contrasted to these enzymes, acid phosphatase activity was demonstrated on the entire Golgi lamellae besides lysosomes, but not on multivesicular bodies, vacuolar bodies and storage granules.

Light and electron microscope histochemistry of alkaline phosphatase in the ventral prostate of rats

Alkaline phosphatase was studied in the ventral prostate of rats by light and electron microscopy. In light microscopy, the enzyme activity was found in the luminal secretion and also on the luminal edge of the acinar walls as well as in the basal area of the acinar walls. It was also found in the walls of periacinar blood capillaries. The enzyme activity was abolished with addition of either L-phenyl-alanine or L-homoarginine and also of L-tartaric acid into the incubating medium. In electron microscopy, the enzyme activity was observed in the luminal secretory material and further it was observed strongly in the sharply localized pittings of apical surface of acinar secretory epithelial cells. The lower lateral and basal surface of the cells showed presence of rather weak activity of the enzyme. The basal cells showed strong activity of the enzyme in pinocytotic vesicles. Further, intense activity of the enzyme was observed on the cell surface of the fibrocytes immediately surrounding acinar basal lamina and also in pinocytotic vesicles of periacinar blood capillaries.

A histopathologic study on the effects of radiofrequency thermotherapy on malignant tumors of the lung

Malignant cells are thermosensitive but this does not fully explain the wide-spread pathologic changes observed in solid cancers following local therapy with radiofrequency heating. The histopathology of human malignant tumors after radiofrequency thermotherapy reveals not only the expected degeneration of tumor cells, but significant changes in the tumor's stroma as well. Stromal blood capillary walls are massively infiltrated with round cells and undergo degenerative changes leading to necrosis and obliteration of the tumor's vascular supply. Extensive infiltration of the stroma with the host's round cells occurs. Following focal necrosis and rupture of the stroma, pools of lymphocytes establish direct contact with heat damaged malignant cells leading to further destruction of persisting tumor. The histologic signs of the generalized breakdown of lung tumors consequent to radiofrequency heat-therapy bear close resemblance to lesions in acutely rejecting organ allografts.

Comparative toxicity in the rat of cytochalasins B and E

T. Glinsukon and S. Lekutai. Comparative toxicity in the rat of cytochalasins B and E. Toxicon 17, 137–144, 1979.—Cytochalasins B and E, produced by molds, were acutely toxic to rats. The ld 50 values for a single i.p. administration of cytochalasin B were: one-day-old rats, 10.6 mg/kg and weanling rats, > 15 mg/kg. Comparable values for cytochalasin E were: one-day-old rats, 1.28 mg/kg and weanling rats 3·5–5·0 mg/kg. One-day-old rats receiving a lethal i.p. dose of either cytochalasin B or E died within 2–8 hr with 0·3 ml fluid in the peritoneal cavity. Histopathologic changes with cytochalasin E included severe congestive necrosis of the liver and kidney whereas cytochalasin B caused congestion only at the edge of the liver. Cytochalasins E (0·5 mg/kg) and B (1·5 mg/kg) produced a maximum decrease of 46·2% and 45·4% respectively in total plasma protein concentrations when a single i.p. dose was given to adult male rats. Cytochalasin B caused a transient reduction in plasma volume within the first hr after administration and the volume gradually increased to the normal value. Maximum reduction of plasma volume and mean arterial pressure occurred 90 min after treatment with either cytochalasin B or E. Cytochalasin B appears to act directly on the walls of blood capillaries permitting extravascular effusion of plasma fluid. It also induces qualitatively different histopathologic changes in the liver and kidney than cytochalasin E.

Effects of cytochalasin E on fluid balance in the rat

A single lethal dose of cytochalasin E (3.50 mg/kg ip) produced a rapid decrease in plasma protein concentrations of adult male Fischer rats (250–300 g). Plasma concentrations of albumin and globulin were reduced within 20 min without significant change in plasma fibrinogen concentration. Reduction of plasma volume paralleled the appearance of fluid at the site of injection; these changes were dose-dependent. At a dose of 1.0 mg/kg (ip) loss of plasma protein occurred in 3 hr; the protein content gradually returned to control values in the following 20 hr. At the same time, there was an accumulation of fluid in the pleural cavity which reached a maximum when the plasma volume had returned to the control value. The intraperitoneal administration of cytochalasin E produced a dose-dependent decrease in mean arterial pressure. There was a biphasic response in plasma glucose concentration following a lethal dose (3.50 mg/kg, ip) of cytochalasin E, a hyperglycemia during the first hour after toxin treatment, followed by a mild hypoglycemia. Liver glycogen content was reduced to 9% of control values within 60 min after treatment. Cytochalasin E appears to act directly on the walls of blood capillaries permitting extravascular effusion of plasma fluid, albumin, and globulin; cause of death is apparently due to shock.

Analysis of fluid in capsules implanted into dog brain.

Perforated capsules were implanted aseptically into the brain parenchyma of dogs. The tissue and fluid formed within these intracerebral capsules (BC) were analysed for their ions and protein content. The results were compared with those for other perforated capsules implanted simultaneously into the subcutaneous tissue and muscle, respectively (denoted SC and MC). The following results were obtained:1) In BC and MC, the Na/K ratio was different from that of the respective control tissues (cerebral parenchyma and temporal muscle) but similar to that of both the tissue in SC and control connective tissue. The water content of the three different capsular tissues was almost identical, but in each case different from that of the respective control tissues.2) The Na/K ratio, Cl and protein content, and electrophoretic patterns of the three capsular fluids were similar to one another, and to serum. However, all (including BC fluid) were different in composition from the CSF (cerebrospinal fluid).3) Investigations of the effect of time lapse after capsular implantation showed that the Na and K content was generally constant over the observed period, except that the K value was high in the initial few weeks.4) Based on the results obtained, and on our data for pressure reequilibration in BC, the nature of the fluid compartment in BC is discussed. It is considered to represent an extension of the narrow space existing physiologically between the blood capillary wall and glial membrane, and not to be part of the true interstitial fluid compartment.5) The barrier existing between the blood and brain parenchyma may be regarded not as a single membrane but as two membranes of dissimilar nature.

Peripheral glucose uptake in relation to physiological levels of plasma and lymph insulin.

Abstract. The effects of physiological increments of plasma immunoreactive insulin upon tissue glucose uptake, tissue insulin uptake and lymph insulin levels were studied in the hind‐limb (65% muscle, 27% skin and subcutaneous fat) of 38 anaesthetized dogs.During intravenous glucose tolerance tests, the tissue glucose uptake remained within baseline values, whereas the net rates of glucose utilization and the concentrations of arterial plasma insulin increased as the load of glucose injected was raised. Significant amounts of endogenous insulin were cleared from plasma but were not recovered in lymph.No glucose response was observed in the hind‐limb tissues during intra‐arterial infusions of exogenous insulin in conditions of strict normoglycaemia and constant blood flow. The infusions of insulin were designed to simulate the levels of endogenous hormone achieved in plasma during the glucose tolerance tests. Again, a high percentage of the injected insulin was fixed to the hind‐limb tissues with no detectable rise of leg‐lymph levels. At higher plasma insulin concentrations, both tissue glucose uptake and lymph insulin levels were increased.The results show that the effect of plasma insulin on glucose uptake by muscle and fat in vivo is a threshold phenomenon. From the present knowledge of the physiology of lymph formation, the threshold phenomenon could largely be accounted for by insulin adsorption to the blood capillary walls.

THE PERMEABILITY OF THE BLOOD CAPILLARIES OF THE LEG TO THE LIPOPROTEINS IN VARIOUS HYPERLIPAEMIC STATES IN THE RABBIT

The transference of lipoproteins across the walls of blood capillaries was determined by measuring the concentration of their components in plasma and in lymph collected from the leg, both before and after injuring the paw by heat. These measurements were made in groups of normal rabbits in which the lipid levels were increased by Triton WR‐1339, cortisone, alloxan or hæmorrhage, and in cholesterol‐fed animals given either Triton or cortisone.The transference of the lipoproteins in all these different hyperlipaemic conditions was considerably increased by injury, and, both before and after injury, varied inverselv with the size of the macromolecules concerned.The results showed that one way in which Triton, cortisone and alloxan might inhibit atherosclerosis in the cholesterol‐fed rabbit was by changing the lipoprotein pattern, decreasing the amount at the lower end and greatly increasing the amount at the upper end of the spectrum in relation to size and Sf values, thereby decreasing the amount of lipoprotein filtered through the vascular endothelium.The composition and stability of lipid in the lymph and, therefore, in the tissue fluid, also varied considerably in the different conditions studied and these factors were also probably important in determining whether or not lipid was deposited in an atherosclerotic lesion.The experiments support the view that small, cholesterol‐rich lipoproteins are the most likely to be deposited in the intima because they are more readily transferred across the endothelium, are rich in cholesterol, which cannot be broken down, and are probably less stable than the lipoproteins in conditions of hypertriglyceridæmia.

STUDIES ON THE INNERVATION OF BONE MARROW WITH SPECIAL REFERENCE TO THE INTRAMEDULLARY NERVE FIBERS IN DOG AND GOAT.

Histological studies on nerve fibers distributed in the bone marrow of young dogs and young goats have been performed, using silver staining methods.1. The nerves to be distributed in the bone marrow enter the medullary cavity through foramina nutricia in the form of a bundle of mixed nerve fibers, consisting of myelinated and non-myelinated ones. They are divided into two groups, nonvascular independent nerves and vascular proper ones.In addition, there are other nerve fibers which enter the medullary cavity through HAVERSian canals.2. The non-vascular independent and the vascular proper nerves form primary plexuses jointly and then give rise to simpler secondary plexuses.3. There are no nerve cells in the primary and the secondary nerve plexuses.4. Such nerve fibers as derived from these nerve plexuses form non-branching free endings of sensory nerve fibers in the interstitial tissue and also form terminal networks of vegetative nerve fibers on the walls of blood capillaries and venous sinuses and in the interstitial tissue.5. It has been ascertained that no terminal network of vegetative nerve fibers envelops free cells directly. This confirmation is different from the result reported by TAKEYAMA, but agrees with that published by STÖHR.

Studies on blood vascular silver-blackened fibers (SF,BSF) related to heart beat and vascular phenomenon in vertebrates. III. Relationships of erythrocytes to the minute architectonic of silver-blackened fibers (SF) in the cardiac muscle and to that of blood vascular silver-blackened fibers (BSF) in blood capillaries of the cardiac muscle.

As part of a series of morphological studies on the heart beat and blood vascular phenomenon in the vertebrated animals, the authors investigated silver-blackened fibers distributed in the blood vascular system. As a result, detailed descriptions were made on the very complicated architectonic of these fibers distributed in the cardiac muscle, the relationship between these fibers and the endothelial cells of blood capillaries, and the presence of some correlations between these fibers and erythrocytes.The following conclusions were drawn from the present investigation.1. A complicated secondary node (an auxiliary node, an atrioauricular relay node) was recognized to exist between the node of silver-blackened fibers so far known and the main trunk of these fibers.2. It was indicated that there was an atrioventricular border node on the boun dary between the atrium and the ventricle in the heart of eel.3. The terminal branches of the peripheral divisions of these fibers distributed in the atrial and ventricular portions of the heart formed a spiral structure, a close contact with the sarcolemma, ramifying endings, and terminal networks.4. In the walls of blood capillaries, silver-blackened fibers are distributed in the area where the basement membrane of the endothelial cells is located. They show a close relationship to the endothelial cells. The adventitial cells are present external to these fibers, there being only a weak direct relationship between these cells and fibers.5. It seemed that the erythrocyte played a very important part in the activation and regeneration of silver-blackened fibers. This presumption was made from the observation on the destruction phenomenon of erythrocytes.Therefore, formation of a node (a secondary node) by silver-blackened fibers, the state of termination of terminal branches, distribution of these fibers in the walls of blood capillaries, and the correlations between these fibers and erythrocytes were clarified in the present investigation. From the results obtained with regard to the distribution and construction of these fibers, it is advocated that these fibers are very closely related to the heart beat and blood vascular phenomenon.