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Results for “CAPILLARITY”

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At least 145 records · Page 8Linked to original sources

PubMed2002

Capillarization in skeletal muscle of rats with cardiac hypertrophy.

PURPOSE: Exercise intolerance during chronic heart failure (CHF) is localized mainly in skeletal muscle. A decreased capillarization may impair exchange of oxygen between capillaries and muscle tissue and in this way contribute to exercise intolerance. We assessed changes in capillary supply in plantaris and diaphragm muscles of a rat aorta-caval fistula (ACF) preparation, a volume overload model for CHF. METHODS: An ACF was created under equithesin anesthesia. Plantaris and diaphragm muscles were removed 6 wk postsurgery and examined for myosin heavy chain (MyHC) content and capillary supply. RESULTS: Cardiac hypertrophy was 96% (P < 0.002) after ACF. The Type IIb MyHC content of the plantaris muscles increased (33.9 +/- 3.3 vs 49.8 +/- 3.8%; mean +/- SEM) at the expense of Type IIa MyHC (17.6 +/- 1.8 vs 11.2 +/- 1.7%) in ACF rats (P < 0.05). In the diaphragm, the number of Type I (32.1 +/- 2.3 vs 40.6 +/- 2.7%) and IIb fibers (40.6 +/- 1.9 vs 49.6 +/- 3.6%) increased at the expense of Type IIa fibers (26.8 +/- 2.5 vs 9.4 +/- 0.9%) (P < 0.05). The capillary number per fiber did not change, and this indicated that no capillary loss occurred with ACF. Also, the capillary density was maintained in the diaphragm and plantaris muscles of ACF rats. Furthermore, the coupling between fiber type, size, and metabolic type of surrounding fibers, with the capillary supply to a fiber, was maintained in rats with an ACF. CONCLUSION: The cardiac hypertrophy induced by volume overload seems adequate to prevent atrophy and changes in the microcirculation of limb and diaphragm muscles.

Animals↗

PubMed2001

Recurrent alveolar hemorrhage and pulmonary capillaritis in the "primary" antiphospholipid syndrome.

Pulmonary involvement in the primary antiphospholipid syndrome (PAPS) has generally been on the basis of thromboembolism. We describe a patient with hemorrhagic alveolitis, a life-threatening complication that must also be considered. The patient was a 63-year-old Caucasian man who had a past history of recurrent deep vein thromboses as well as an arterial occlusion of the left popliteal artery and who developed hemorrhagic alveolitis and capillaritis at age 57 years, which was treated with long-term cyclophosphamide, steroids, and anticoagulation. Four years later, he had a recurrence of the same condition, and a positive lupus anticoagulant test was found. Severe thrombocytopenia, diagnosed as idiopathic thrombocytopenic purpura, was treated with platelet transfusions and increasing steroid dosage. Hemorrhagic adrenal infarction supervened at this time, and a septicemic illness was treated with intravenous antibiotics. Diffuse alveolar pulmonary hemorrhage is an unusual complication of the APS that is being increasingly reported, and recognition of its possible fatal course is of great importance for the treating physician. Severe thrombocytopenia that could contribute to hemorrhage may also accompany the APS, but this is unusual.

Journal Article↗

PubMed2004

Pulmonary capillaritis and hemorrhage in neonatal lupus erythematosus (NLE).

We describe the case of an infant who presented to our institution with tachypnea, cough, and hypoxemia. The baby had been diagnosed with complete heart block (heart rate 50-60 beats/min) in utero and had a pacemaker placed at birth. The mother was found to have both anti-Ro and anti-La antibodies. At age 3 months, the chest radiograph showed diffuse bilateral interstitial infiltrates. A lung biopsy confirmed the presence of necrotizing capillaritis and alveolar hemorrhage, which is an infrequent complication in pediatric patients with systemic lupus erythematosus. The patient did well after recognition and aggressive treatment of this previously unrecognized complication of neonatal lupus.

Journal Article↗

PubMed2006

Macroscopic capillarity and hysteresis for flow in porous media.

A macroscopic theory for capillarity in porous media is presented, challenging the established view that capillary pressure and relative permeability are constitutive parameter functions. The capillary pressure function in the present theory is not an input parameter but an outcome. The theoretical approach is based on introducing the residual saturations explicitly as state variables [as in Phys. Rev. E 58, 2090 (1998)]. Capillary pressure and relative permeability functions are predicted to exist for special cases. They exhibit hysteresis and process dependence as known from experiment.

Journal Article↗

PubMed1996

Sinusoidal capillarization and arterial blood supply continuously proceed with the advance of the stages of hepatocarcinogenesis in the rat.

Hepatocellular carcinoma (HCC) is supplied only with arterial blood and has capillaries instead of sinusoids, unlike the normal hepatic tissue. In order to reveal the sequential changes of sinusoidal structure and blood supply during hepatocarcinogenesis, we examined hyperplastic nodules (HPN), atypical hyperplastic nodules (AHPN) and HCC in F344 rats fed with 2-acetylaminofluorene for 25-35 weeks. The extent of arterial blood supply and the degree of sinusoidal capillarization were assessed by the staining of hepatic nodules with arterially infused ink and by immunohistochemical and ultrastructural analyses of the sinusoids, respectively. The proportion of arterialized nodules was 47% in HPN, 57% in AHPN and 85% in HCC, which indicates that arterialization begins at the stage of HPN and a few HCC still receive portal venous blood. The proportion of Factor-VIII-related antigen (F-VIII)-positive nodules was 25% in HPN, 40% in AHPN and 100% in HCC. Non-arterialized nodules did not express F-VIII, while some F-VIII-negative nodules were already arterialized. Electron microscopically, non-arterialized HPN exhibited normal features of sinusoids, while arterialized HPN showed disappearance of Kupffer cells and partial defenestration of sinusoidal endothelial cells. In non-arterialized and arterialized AHPN, basement membrane became continuous and lipid droplet-containing stellate cells were no longer seen. In HCC, endothelial fenestrae were diminished and basement membrane became thick. The present study has demonstrated that sinusoids are altered in the following order as hepatocarcinogenesis advances from HPN to HCC; onset of arterialization and decrease of endothelial fenestrae, expression of F-VIII by endothelial cells, disappearance of Kupffer cells, diminution of lipid droplets in stellate cells and thickening of basement membrane.

Animals↗

PubMed2005

Peritubular capillaritis in early renal allograft is associated with the development of chronic rejection and chronic allograft nephropathy.

Peritubular capillaritis (PTCitis) has been recognized as one form of acute/active allograft rejection, and its relation to humoral immunity has been suggested. However, its mechanisms remain to be fully clarified, and there are no criteria for evaluating the extent of PTCitis in a biopsied allograft. In this study, we first evaluated the extent of PTCitis in early allografts in patients presenting with acute cellular rejection (ACR) and antibody-mediated rejection (AbAR). We also included patients who showed no evidence of ACR and/or AbAR. Next, we investigated whether or not PTCitis persisted and if peritubular capillary basement membrane (PTCBM) thickening was present in their follow-up biopsy specimens. We adopted the scoring system of PTCitis, which was presented at the Seventh Banff Conference on Allograft Pathology in 2003. In total, 53 patients were included in this study. At first biopsy, 17 showed ACR, eight showed AbAR, 16 showed mild PTCitis only, and 14 were without significant pathologic changes. The PTC score was the highest in the AbAR group, and in some patients the score gradually increased during the follow-up period. Similar changes were also observed in the group with mild PTCitis only. In late allografts, half of the patients with AbAR developed chronic rejection (CR), and the PTCBM score was the highest in that group. Surprisingly, CR was present in more than 30% of patients without ACR and/or AbAR but mild PTCitis only. In the control group, only a few showed CR and/or chronic allograft nephropathy (CAN). In conclusion, it became clear that we should carefully monitor for mild PTCitis in early allografts. In addition, our data also proved the usefulness of the PTC score and PTCBM score.

Acute Disease↗

PubMed1990

[The capillarization of the M. pectoralis of the turkey (Meleagris gallopavo) from hatching to the 280th day of life].

The capillarization of the M. pectoralis was examined in the turkey as it changed with age. Examined was the density of the muscles fibers (per mm2), the density of the capillaries (per mm2) and the quotient muscle fibers/capillaries. In accordance with the sequence of the original data four functions of organismic growth (slightly altered) were utilized for the approximation of the data for descending amounts: Pütter/Bertalanffy (1920, 1934); Richards (1959); Janoschek enlarged after Sager (1980) and Richards enlarged after Sager (1980). The approximations were made via nonlinear regressions, whereby the sum of the error amounts and the sums of the error squares served as criteria of quality. The results including the deduced initial and end amounts are combined in tables which also contain the parameter of the way the computations were conducted.

Aging↗

PubMed1981

Adaptive changes in work capacity, skeletal muscle capillarization and enzyme levels during training and detraining.

Six male subjects exercised on a bicycle ergometer 30 min with left leg and 30 min with right leg 3 times a week for 8 weeks. This training resulted in a 14.6% increase in VO2 max with two-leg exercise and a 23.1% increase with one-leg exercise. A significant decrease towards pretraining VO2 max was seen during the following 8 weeks of detraining. Muscle biopsy samples were obtained at rest from m. vastus lateralis before and after training and 4 and 8 weeks after training. During training the number of capillaries per mm2 and the number of capillaries per fiber increased about 20%. The number of capillaries around each fiber type (CA) increased 20--30%. The average area of each fibre type increased only about 5%. The fibre area per CA decreased by about 10%. During 8 weeks of detraining decreases were seen in the number of capillaries per fibre, CA and in fibre area, while fibre area per CA and number of capillaries per mm2 were almost unchanged at the end of the detraining period. Pronounced increases in activities of oxidative enzymes were observed after training, while only minor increases were seen in glycolytic enzyme activities. All enzyme activities decreased towards pre-training levels during detraining. The results indicate that the training-induced improvement in oxidative capacity and in muscle capillarization expressed as capillaries per fibre and CA disappears within 8 weeks after cessation of training. However, the fibre area per CA and number of capillaries per mm2 point at a favourable long term effect on the average diffusion distance between capillaries and muscle fibres.

Adaptation, Physiological↗

PubMed1986

The time dependence of training-induced increase in skeletal muscle capillarization and the spatial capillary to fibre relationship in normal and neovascularized skeletal muscle of rats.

One hundred and eighty-four rats of different ages were investigated regarding the basic capillary-fibre array and the array resulting from capillary proliferation induced by swimming training and dipyridamole treatment. The time dependence of the training-induced capillary increase in the muscle was also investigated. Sections of the medial portion of the quadriceps femoris muscle were evaluated in light microscope for total capillarization, fibre area and fibre type composition. After 4 and 8 weeks of swimming training, increases in capillary density, capillary to fibre ratio and mean number of capillaries in contact with each fibre were recorded. No changes in muscle fibre area or fibre composition were seen. In all groups the majority of the capillaries was in contact with three muscle fibres. The capillary proliferation induced by training and dipyridamole treatment was confined to the capillaries in contact with two and three fibres. The results indicate a basic hexagonal capillary-fibre array with a possible position for a capillary in each corner of the hexagon. This pattern is retained in the increased vascularity induced by swimming training and dipyridamole treatment.

Animals↗

PubMed1997

A new measurement of tissue capillarity: the capillary-to-fibre perimeter exchange index.

The surface area of contact between capillaries and muscle fibres has been suggested to be the site of greatest oxygen flux density in the movement of oxygen from the capillaries to the muscle fibres. A new measurement of tissue capillarity, designed specifically for use on non-perfusion fixed muscle tissue (i.e., that obtained via needle biopsy), is presented that describes the capillary supply from this perspective. The Capillary-to-Fibre Perimeter Exchange Index (the CFPE Index) is derived as the quotient of the individual capillary-to-fibre ratio (i.e., the capillary-to-fibre ratio calculated for each fibre individually) and the fibre perimeter. This method is suggested to provide a means of quantitating potential alterations in the capacity for oxygen flux (e.g., as may occur in response to a training intervention) and any carrier- or receptor-mediated aspect of blood-tissue exchange between the capillaries and muscle-fibres (e.g., insulin or glucose delivery).

Animals↗

PubMed1987

Long-term isoprenaline administration produces an increase in capillarity in the soleus muscle of the rat.

The effects of isoprenaline administration (300 micrograms/kg for 5 weeks) on rat soleus muscle capillarity and glycolytic and oxidative capacities were evaluated. The treatment resulted in ventricular hypertrophy. The activities of lactic dehydrogenase, pyruvate kinase, citrate synthase, and cytochrome c oxidase in soleus muscle homogenates were not different between control and isoprenaline-injected animals. Capillaries were visualized in muscle cross sections treated to demonstrate ATPase activity after acid preincubation. Capillary density was higher in the experimental (873 +/- 38 capillaries/mm2) than in the control (713 +/- 33 capillaries/mm2) animals. Capillary to fiber ratio was also higher in the experimental (2.47 +/- 0.10) than in control (2.09 +/- 0.08) animals, but fiber cross-sectional area was not changed by the treatment (2836 +/- 87 microns2 in controls and 2951 +/- 136 microns2 in experimental). A plot of capillary to fiber ratio vs. fiber cross-sectional area showed that at a given fiber cross-sectional area the value of capillary to fiber ratio of the treated animals was higher than that of the controls. This indicates that treatment resulted in the proliferation of microvessels. The results suggest that prolonged beta-adrenergic stimulation results in the development of new capillaries but that this is not accompanied by increases in the oxidative capacity of the soleus muscle of the rat.

Animals↗

PubMed1981

Capillarity and blood flow of transplanted skeletal muscles of cats.

After transplantation, skeletal muscle fibers and the microvasculature degenerate and then regenerate. The structural and functional characteristics of autografted muscle change with time and ultimately stabilize. Capillarity, blood flow, or fatigability was measured in control (total n = 22) and in autografted (total n = 42) extensor digitorum longus muscles of cats. From 10 to 180 days after transplantation, the capillaries per square millimeter in peripheral areas of autografts averaged 65% of control, and from 180 to 518 days, 45% of control. Resting blood flow in autografts increased eventually from total ischemia at the time of transplantation to values 400% of control. After 400 days, resting blood flow returned to control values. The blood flow of autografts increased in response to twitch stimulation, reaching maximal value (24.4 +/- 1.4 ml . 100 g-1 . min-1) at 1 twitch . s-1 . The maximal blood flow of autografts was comparable to the submaximal blood flow at 1 twitch . s-2 of controls and was 30% of the maximal flow of controls obtained at 4 twitches . s-1. The maximal blood flow in autografts did not increase from 80 to 460 days. When stimulated with repetitive twitches, autografts fatigued more rapidly than controls.

Action Potentials↗

PubMed1983

Capillarity and fiber types in the cremaster muscle of rat and hamster.

We determined muscle fiber type and capillarity in cremaster muscle samples from rats and hamsters of different ages. Histochemical estimation of oxidative capacity was made from the activity of either nicotinamide dinucleotide tetrazolium reductase (NADH-TR) or succinic dehydrogenase (SDH), and fibers were termed fast or slow from myofibrillar ATPase activity. Fibers were classified as type I (low ATPase, high NADH-TR/SDH), type IIa (high ATPase, high SDH/NADH-TR), type IIb (high ATPase, low SDH/NADH-TR), or type IIc (no acid reversal of ATPase, high NADH-TR). Type IIb fibers accounted for 60-80% of the muscle area in both species at all ages. The principal change with maturation was muscle fiber hypertrophy. Mean cross-sectional fiber area increased from 488 +/- 70 (SE) and 453 +/- 19 micron2 in young hamsters and rats, respectively, to 1,255 +/- 99 and 1,540 +/- 101 micron2 in adults. Capillary density (no. of capillaries/mm2 tissue) paralleled fiber hypertrophy; it decreased significantly with maturation from 684 +/- 60 (SE) to 228 +/- 26/mm2 in hamsters and from 341 +/- 15 to 213 +/- 15/mm2 in rats. In vitro estimates of capillary density are compared with previously obtained in vivo data (31), and sources of error are identified. We conclude that reported differences in microvascular function in the cremaster muscle in vivo during maturation or between species cannot be ascribed to changes in muscle composition.

Abdominal Muscles↗

PubMed1990

Spatial heterogeneity in striated muscle arteriolar tone, cell flow, and capillarity.

Spatial variations in microvascular function are described at two tissue sites in hamster cremaster muscle (pentobarbital sodium, 70 mg/kg ip). Arterioles observed include terminal arterioles and their feeding vessels, termed capillary network controllers (CNC). Although terminal arterioles at both sites had similar maximum diameters and cell flows, those at site I were significantly more constricted at rest (2.7 +/- 0.3 vs. 5.1 +/- 0.3 microns at site II) and showed lower resting flows (19.0 +/- 5.5 vs. 174 +/- 34 cells/s at site II). There were no spatial differences in CNC maximal parameters or CNC resting tone, yet CNC resting flow at site II (798 +/- 118 cells/s) significantly exceeded the value at site I (460 +/- 85 cells/s). At rest, median capillary cell flow at site I (3.3 cells/s) was half that at site II (6.3 cells/s). During hyperemia, perfused capillary segment length per unit volume was 84% greater at site I and estimated tissue erythrocyte content nearly double that at site II. Thus significant spatial differences in microvascular function exist in cell flow and vessel tone among terminal arterioles, in cell flow among CNC, and in capillarity and indices of capillary exchange.

Animals↗

PubMed1998

Time course of changes in capillarization in hypertrophied rat plantaris muscle.

The time course of angiogenesis during hypertrophy of the rat plantaris muscle was studied by using a unilateral, synergistic ablation model. Animals (n = 6/group) were euthanized 2, 5, 7, 15, 21, and 30 days postmyectomy. Sections from both the hypertrophied and contralateral muscles were simultaneously stained for capillaries and muscle fiber type. Mean fiber cross-sectional area (FA) and various indexes of capillarity were determined by using a video analysis system. The capillary supply to individual fibers, assessed as the FA supplied per capillary contact, remained unchanged until day 21 (compared with day 2) and exhibited a significant increase at day 30. Analysis of the time course of capillary development on the basis of the number of capillary contacts per fiber, and of hypertrophy on the basis of FA, yielded half-lives of 10.1 and 11.2 days, respectively. It was concluded that angiogenesis during muscle overload is tightly coupled to the changes in FA, which could suggest that the two processes are initiated and/or driven by some common factor(s).

Animals↗

PubMed2002

Selected contribution: skeletal muscle capillarity and enzyme activity in rats selectively bred for running endurance.

To attempt to explain the difference in intrinsic (untrained) endurance running capacity in rats selectively bred over seven generations for either low (LCR) or high running capacity (HCR), the relationship among skeletal muscle capillarity, fiber composition, enzyme activity, and O(2) transport was studied. Ten females from each group [body wt: 228 g (HCR), 247 g (LCR); P = 0.03] were studied at 25 wk of age. Peak normoxic maximum O(2) consumption and muscle O(2) conductance were previously reported to be 12 and 33% higher, respectively, in HCR, despite similar ventilation, arterial O(2) saturation, and a cardiac output that was <10% greater in HCR compared with LCR. Total capillary and fiber number in the medial gastrocnemius were similar in HCR and LCR, but, because fiber area was 37% lower in HCR, the number of capillaries per unit area (or mass) of muscle was higher in HCR by 32% (P < 0.001). A positive correlation (r = 0.92) was seen between capillary density and muscle O(2) conductance. Skeletal muscle enzymes citrate synthase and beta-hydroxyacyl-CoA dehydrogenase were both approximately 40% higher (P < 0.001) in HCR (12.4 +/- 0.7 vs. 8.7 +/- 0.4 and 3.4 +/- 0.2 vs. 2.4 +/- 0.2 mmol. kg(-1). min(-1), respectively), whereas phosphofructokinase was significantly (P = 0.02) lower in HCR (27.8 +/- 1.2 vs. 35.2 +/- 2.5 mmol. kg(-1). min(-1)) and hexokinase was the same (0.65 +/- 0.04 vs. 0.65 +/- 0.03 mmol. kg(-1). min(-1)). Resting muscle ATP, phosphocreatine, and glycogen contents were not different between groups. Taken together, these data suggest that, in rats selectively bred for high-endurance exercise capacity, most of the adaptations for improved O(2) utilization occur peripherally in the skeletal muscles and not in differences at the level of the heart or lung.

Animals↗

PubMed1987

Failure of swimming exercise to improve capillarization in cardiac hypertrophy of renal hypertensive rats.

Female Sprague-Dawley rats were made hypertensive by the two kidney/one clip Goldblatt procedure, while control animals were sham-operated. One week later, half of the animals were subjected to a moderate swimming exercise and the other half remained sedentary. Thus, four experimental groups, each consisting of 14 rats, were formed: control animals that were exercised or kept sedentary and corresponding renal hypertensive animals either exercised or sedentary. In hypertensive rats, a significantly increased left ventricular weight and reduced coronary reserve were found. Cardiac hypertrophy in hypertensive rats was characterized by a lower number of capillaries on a tissue cross-section, larger heterogeneity of the capillary net, and a less uniform orientation of capillaries in space. Total length of capillaries in the hypertrophic hearts increased significantly, but less than the increase in cardiac weight, resulting in reduced capillary length density. Chronic swimming for 2 hr/day for a period of 6 weeks, subsequent to a 4-week acclimation period, did not significantly influence any of the investigated indexes of capillaries from hypertrophic hearts. In the normotensive rats, chronic swimming resulted only in a moderate increase in total capillary length associated with a small increase in the left ventricular weight of similar degree. Thus, chronic exercise in normotensive rats induced a moderate increase in total capillary length per left ventricle, while it did not alleviate impaired capillarization of hypertrophic hearts from hypertensive rats.

Animals↗

PubMed1998

Diffuse alveolar hemorrhage with underlying pulmonary capillaritis in the retinoic acid syndrome.

All-trans-retinoic acid (ATRA) can induce a clinical remission in patients with acute promyelocytic leukemia. An adverse condition called "retinoic acid syndrome" limits this therapy. It is characterized by fever and respiratory distress, along with weight gain, pleural or pericardial effusions, peripheral edema, thromboembolic events, and intermittent hypotension. The lung disease has been previously ascribed to an infiltration of leukemic or maturing myeloid cells into lung parenchyma, which is sometimes associated with pleural effusions and diffuse alveolar hemorrhage. We report a case of retinoic acid syndrome in an 18-yr-old woman who developed diffuse alveolar hemorrhage while being treated with ATRA for acute promyelocytic leukemia. An open lung biopsy revealed pulmonary capillaritis.

Adolescent↗