Biomedical subjects

Y Nara

Publications and source records attributed to Y Nara.

At least 91 records · Page 5Linked to original sources

PubMed1995

[Electrophysiologic evaluation of entrapment neuropathy caused by scar formation in recurrent motor branch of the median nerve].

A unique case of mononeuropathy was encountered in a 20-year-old man with isolated involvement of the recurrent motor branch of the right median nerve following a skiing accident one year previously. There was also isolated involvement of the right thenar muscles innervated by the median nerve. Sensation was intact in the right hand and fingers. Conventional conduction studies in the right median nerve yielded no abnormal findings except a reduction in the amplitude of the muscle action potential. However, insertion of a needle electrode into the abductor pollicis brevis muscle revealed some delayed motor unit potentials following electrical stimulation at the wrist. We performed surgery and found the right recurrent motor branch to be entrapped by fibrous scar tissue 3 to 4 mm distal to branching from the median nerve. Direct recordings made from the nerve trunk using a tungsten microelectrode with supramaximal stimulation at the elbow revealed reduced amplitude of the compound nerve action potential distal to the site of entrapment. We concluded that scar tissue resulting from the previous injury had compressed the recurrent motor branch, causing this unique neuropathy.

Adult↗

PubMed1995

[Intraneural topography of the median nerve at the elbow level--an analysis using intraneural neurography].

We examined intraneural topography of the median nerve at the elbow level by means of intraneural neurography in 38 individuals. A tungsten microelectrode was inserted into the median nerve trunk at the elbow where largest amplitude of the nerve action potential could be obtained with stimulations over median nerve trunk at the wrist. Each of six areas innervated by the nerve was stimulated supramaximally. The ratio of the amplitude of the nerve action potentials stimulated in each area to that stimulated over median nerve trunk at the wrist was arbitrary defined as territory index. the territory indices of six areas, i.e., thumb, index finger, middle finger, ring finger, little finger and thenar area, were 12%, 14%, 15%, 7%, 0% and 5%, respectively. Based on the investigation of permutations and combinations, the cutaneous fibers in the median nerve trunk at the elbow may be arranged in order of thumb-index-middle-ring fingers from the radial side, and the muscle fibers to the thenar muscles may be located at the palmar side to the index finger area. These results were in accordance with the previous reports obtained by near nerve recordings or anatomical analysis at the wrist. In 42% of the subjects a part of fibers in the median nerve were considered to innervate also little fingers, even though territory index was very small. This method has made it possible to estimate the intraneural topography of the median nerve at the elbow level and to detect Martin-Gruber anastomosis with a small number of sensory fibers.

Action Potentials↗

PubMed1995

[Detection of subclinical sensory nerve dysfunction in amyotrophic lateral sclerosis--a microneurographic study].

In amyotrophic lateral sclerosis (ALS) sensory function has been considered to be normal on a clinical basis. There are, however, several pathologic reports indicating that peripheral sensory fibers are involved in ALS. To evaluate changes in sensory nerve function quantitatively, we measured compound nerve action potentials (CNAP) of the median nerve by means of intraneural microneurography (MNG) and compared the results between 16 patients with ALS, age-matched 13 patients with Parkinson disease (PD) and 13 healthy controls. A tungsten microelectrode with a tip diameter of 1 micron was inserted percutaneously into the median nerve trunk at the elbow. With supramaximal electric stimulation on the median nerve at the wrist, the largest CNAP was recorded. The configuration of the CNAP was similar among three groups, consisting of a large triphasic wave followed by small multiphaic waves. In ALS patients the peak to peak amplitude (Amp) of the triphasic wave was 189.0 +/- 49.8 microV (mean +/- SD), which was significantly smaller than 273.1 +/- 90.0 microV in PD patients and 325.4 +/- 81.0 microV in normal controls (p < 0.01). The maximal nerve conduction velocity (NCV) in ALS was also reduced when compared with that in PD patients and in normal controls (p < 0.05). The average reduction in Amp in ALS was 58% of that in normal controls, while decrease in NCV was less apparent than Amp and 96% of normal controls. The Amplitude of nerve action potentials is considered to represent the density of large myelinated fibers more than 7 microns around the microelectrode.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1995

Detailed examination of vascular lesions triggered by an inhibitor of endothelium-derived relaxing factor.

BACKGROUND: Inhibition of an endothelium-derived relaxing factor (EDRF) may contribute to the pathogenesis of thrombotic arterial occlusions. EXPERIMENTAL DESIGN: We measured the blood pressure and urinary excretion of protein, sodium, and potassium and histologically examined the brains, hearts, and kidneys in normotensive Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) fed on a diet containing: (a) EDRF inhibitor (L-N-nitroarginine:L-NNA); (b) L-arginine, which reverses the effect of L-NNA; or (c) both L-NNA and L-arginine for 1 to 8 weeks. In addition, we examined L-NNA-treated SHRSP, the blood pressures of which were lowered using hydralazine. Furthermore, we produced and examined Goldblatt's renal hypertensive rats, which are of a different type from those resulting from the L-NNA treatment. RESULTS: Both WKY and SHRSP rats fed on a diet containing L-NNA suffered from hypertension and cerebral infarctions in a dose-dependent manner. Cerebral infarctions occurred whether or not SHRSP rats were treated with an antihypertensive agent when they were fed a high dosage of L-NNA. In contrast, SHRSP rats, treated simultaneously with both L-NNA and L-arginine, suffered few cerebral infarctions, although they were severely hypertensive. In addition, there were no cerebral infarctions in Goldblatt's renal hypertensive rats, although they suffered from advanced hypertension. CONCLUSIONS: The data indicate that the inhibition of EDRF injures the vessel walls and encourages platelet adhesion to the damaged areas. The adhering platelets narrow the lumen with resultant thrombotic arterial occlusions. Pathophysiologic conditions that decrease EDRF synthesis appear to play an important role in cerebral, renal, and myocardial infarctions.

Animals↗

PubMed1995

Computer-assisted instruction of arrhythmia for MS-windows.

1. INTRODUCTION. Training in the diagnosis of arrhythmias is an important part of the curriculum for medical students, postgraduates, and paramedical staff. Although several CAI for arrhythmia have been developed [1-3], we could not get CAI software for arrhythmia for the MS-Windows environment. In this report, we present a newly-developed computer-assisted reference system for arrhythmia that functions in the Windows environment. 2. DESCRIPTION OF THE SYSTEM. The system consists of a program and two data files. An MS-Windows program (ECG9405.EXE, 180kB) was compiled using Borland's C++ v.3.1. A binary file (ECPAT.BAS 33kB) includes data of normal and abnormal wave segments of ECG: P wave, PQ interval segment, and QRs complex with/without T wave. A mother file (ECG9405.sys, 57kB) includes 85 data sets to generate ECG waveforms of arrhythmia. Each data set contains a sequence of wave form numbers, the text for questions and answers, and the commands strings. There are five major commands: 1) to create a new window as "wave window"; 2) to make electrocardiogram data; 3) to plot the data on the window; 4) to create a "dialog box" for questions and explanations; and 5) to check the answers. he program gets a data set from the data according to the user's choice. The program then interprets the data set and executes the commands. The wave segment data are plotted in a "wave window" at every 10 milliseconds; this is controlled by the MS-Windows' timer. The timer interval can be changed by selecting the speed button. The ECG waveforms are displayed on a window just like an ordinary ECG monitor with beat sound. Many windows can be created by the user and many ECG waves simultaneously plotted on CRT. 3. USAGE OF THE SYSTEM. The "main window" has a menu that has three items corresponding to the training course: BASIC, TRY, and TEST. Thirty-five types of arrythmias are listed in the "list box" of the windows in BASIC course e.g., sinus arrhythmia, atrial flutter, atrial premature contraction, ventricular extrasystole, ventricular flutter, etc. If the user selects one of them on the list by double clicking, some textual explanations of the wave are described in a dialog box. Ten multiple choice questions are displayed in the dialog box in course of learning TRY and TEST; the answers to these are requested. In the TEST course, the system offers random access to each arrhythmia. he user can send the pictorial ECG data in the window to other graphics programs through a clip board. 4. DISCUSSION. It was successfully used in a lecture of electrocardiogram for medical students. They seem to be interested in this system because of its simple usage and the dynamic drawing of ECG waves on CRT. Multiple computer-based medical resources can be run on MS-Windows. The system is able to run simultaneously with other programs, such as an electronic reference system [4]. The system may be obtained from the authors upon request.

Arrhythmias, Cardiac↗

PubMed1995

In search of genes causing spontaneous hypertension.

1. Basal high blood pressure (BP) in the male and female F2 progeny produced by crosses between Wistar Kyoto rats (WKY/lzm) and stroke-prone spontaneously hypertensive rats (SHRSP/lzm) linked strongly with the leukosialin locus on chromosome 1. 2. Excess salt intake caused elevation of BP and the response was larger in the females than the males. 3. In the male F2 progeny, salt-sensitive hypertension significantly cosegregated with the RR1023 marker on chromosome 10, rather than with the angiotensin converting enzyme locus. 4. In the female F2 progeny, salt-sensitive hypertension significantly linked with the MitR244 marker on chromosome 3.

Analysis of Variance↗

PubMed1995

Ethnicity, environment and salt-sensitivity in cardiac study: epidemiological implications for prevention.

1. An association between Na and blood pressure (BP) was studied in the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study, an international cross-sectional epidemiological study, involving 55 populations from 25 nations. 2. The partial regression coefficient of BP against 24 h urinary Na was calculated in a multiple linear regression model, by adjusting other confounding factors. This demonstrated different distribution in each of several groups stratified according to their ethnicity and geographical location. 3. The relationship of urinary K to BP regression against urinary Na excretion was investigated to clarify its role in the association of Na with BP. 4. Urinary Na/K ratio showed a significant inverse linear relationship with the regression coefficient of BP on urinary Na excretion among seven Japanese populations. 5. The effect of K was to increase urinary Na excretion, as the ratio of Na/K might modify the association between Na and BP.

Blood Pressure↗

PubMed1994

Fish protein-rich diet attenuates hypertension induced by dietary NG-nitro-L-arginine in normotensive Wistar-Kyoto rats.

1. Dietary 0.023% NG-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthesis, induced hypertension in normotensive Wistar-Kyoto rats (WKY). This hypertension was significantly attenuated in WKY given a fish protein-rich diet. 2. The supplement of 2% L-arginine given in a standard diet or a diet containing 3% taurine for drinking did not significantly affect the development of hypertension induced by L-NNA in WKY. 3. WKY which received the standard diet mixed with 10% urea and 0.023% L-NNA had significantly attenuated hypertension compared with WKY receiving the standard diet mixed with 10% kaolin and 0.023% L-NNA. 4. These results suggest that the attenuation of hypertension in L-NNA-treated WKY rats given a fish protein rich diet may be partly caused by urea, a metabolic end-product of protein.

Animals↗

PubMed1994

Comparison of salt sensitivity of male and female F2 progeny from crosses between WKY and SHRSP rats.

1. The present study compared the salt sensitivity of male and female F2 progeny obtained from crosses between Wistar-Kyoto/Izumo rats and stroke-prone spontaneously hypertensive rats (SHRSP A3b/Izm) after salt loading for 7 months. 2. Average systolic blood pressure in male F2 progeny was 10 mmHg higher than that of female F2 progeny at 5 months without salt loading. 3. The blood pressure in male F2 progeny was raised significantly 2 months after salt loading, but there was no further significant change in blood pressure even though salt loading was continued for 5 months. 4. In female F2 progeny, however, a significant change in systolic blood pressure was observed 1 month after salt loading and there was a further significant rise in blood pressure over 6 months. 5. Angiotensin I-converting enzyme and RR1023 loci were strongly linked to systolic and diastolic blood pressures in the male but not the female F2 progeny after salt loading for 7 months. 6. We therefore speculate that the hormonal difference between sexes might influence salt sensitivity in the SHRSP.

Animals↗

PubMed1994

Immunohistochemical characterization of extracellular matrix components of granulosa cell tumor of ovary.

In order to clarify the characteristics of granulosa cell tumors of the ovary, extracellular matrix components were investigated by immunohistochemical techniques. Twenty-three granulosa cell tumors (GCT; eight juvenile and 15 adult type) were studied in comparison with non-neoplastic granulosa cells of human ovaries. In all 23 cases of GCT, chondroitin 6-sulfate proteoglycan revealed with antibody 3B3 was characteristically observed in the extracellular matrix in the solid nest, as well as in microfollicles. In the juvenile cases, the extracellular matrix also contained large proteoglycan (PG) revealed with antibody 2B1. Macrofollicles as well as microfollicles contained PG chondroitin 6-sulfate side chains with a significant amount of chondroitin 4-sulfate. By biochemical analysis using high pressure liquid chromatography, it was also found that disaccharide composition of glycosaminoglycan fractions extracted from granulosa cell tumor tissues consisted mainly of 2-acetamide-2-deoxyl-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-6-O-sulfo-D-galactose (delta Di-6S). The characteristic feature of granulosa cell tumors is the accumulation of chondroitin sulfate PG, especially chondroitin 6-sulfate PG, which may be synthesized by the tumor cells themselves. Immunohistochemical characterization of the extracellular matrix components (collagen, laminin, heparan sulfate PG, chondroitin 4-sulfate PG) was also studied in relation to chondroitin 6-sulfate PG localization.

Adolescent↗

PubMed1994

Effect of dietary magnesium supplementation on intralymphocytic free calcium and magnesium in stroke-prone spontaneously hypertensive rats.

The effects of dietary magnesium (Mg) supplementation on intralymphocytic free Ca2+ ([Ca2+]i) and Mg2+ ([Mg2+]i) were examined in the stroke-prone spontaneously hypertensive rats (SHRSP) at the age of 10 weeks. After 40 day Mg supplementation (0.8% Mg in the diet), systolic blood pressure (SBP) was significantly lower in Mg supplemented group (Mg group) than the control group (0.2% Mg). [Ca2+]i was significantly lower and [Mg2+]i was significantly higher in Mg group than in the control group. Further, [Ca2+]i was positively and [Mg2+]i was negatively correlated with SBP. These results suggest that dietary Mg supplementation modifies [Ca2+]i and [Mg2+]i, and modulates the development of hypertension.

Animals↗

PubMed1994

Nutritional factors for stroke and major cardiovascular diseases: international epidemiological comparison of dietary prevention.

OBJECTIVE: To assess the relationship of biological markers of dietary factors with blood pressure (BP) (Core Study) and with age-adjusted mortality rates of stroke and ischemic heart disease (Complete Study) in the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study, a multicentre epidemiological study in 55 centres of 24 countries as of 1993. DESIGN AND METHODS: From each population, 100 men and 100 women aged 48 to 56 years were randomly selected for BP measurement, 24-hour urine collection, blood tests, etc. Various biological dietary markers from the urine and blood were analysed centrally. Age-adjusted mortality rates from stroke and ischemic heart disease were obtained from 19 centres in 14 countries. RESULTS: Core Study: Cross-centre analyses, using simple linear regression, showed a positive relationship of body mass index to systolic BP and diastolic BP in men (p < 0.001) and women (p < 0.05). There were also strong positive correlations between 24-hour sodium excretion rates and both systolic and diastolic BP (both p < 0.01) in men. An inverse relationship was found between the 24-hour magnesium/creatinine excretion ratio and diastolic BP (p < 0.05) in men. Complete Study: Stroke mortality was significantly positively related to the 24-hour sodium excretion rate in men (p < 0.01) and to the sodium/potassium ratio in both sexes (p < 0.05). It showed an inverse relationship of serum phospholipid with serum total cholesterol (p < 0.05) and a positive relationship with arachidonic acid. A strong positive relationship between serum cholesterol level and ischemic heart disease (p < 0.001) was observed in men. The serum phospholipid n-3 polyunsaturated fatty acid (PUFA) level and the PUFA to saturated fatty acid (SFA) ratio were significantly inversely correlated with ischemic heart disease. The 24-hour taurine excretion rate, a biological marker of seafood protein intake, showed a significant inverse correlation with ischemic heart disease in both sexes (p < 0.01). CONCLUSION: The Core Study revealed a consistent adverse effect of high body mass index and excess salt intake on BP and a beneficial effect of magnesium on BP. The Complete Study demonstrated an adverse effect of high sodium, low potassium intake and hypercholesterolemia on stroke; and an adverse effect of cholesterolemia as well as beneficial effects of serum phospholipid n-3 PUFA, PUFA/SFA and the taurine excretion rate on death from ischemic heart disease.

Arachidonic Acids↗

PubMed1994

The association between salt sensitivity of blood pressure and some polymorphic factors.

OBJECTIVE: To examine the association in Japanese subjects between the salt sensitivity of blood pressure and polymorphic factors. DESIGN AND METHODS: One hundred and four patients with essential hypertension were classified as salt-sensitive or non-salt-sensitive depending on their blood pressure response to salt restriction. An insertion/deletion polymorphism of the angiotensin converting enzyme (ACE) gene was examined by detecting an alu sequence in intron 16. The ACE genotype was classified as II, ID or DD depending on whether each allele had this sequence. The haptoglobin phenotype was determined by the starch-gel electrophoresis method, and was classified as three phenotypes, 1-1, 2-1 or 2-2 form. RESULTS: The response of plasma renin activity to salt restriction was greater in patients with the DD form than in those with other forms, although there were no significant differences in the ratio salt-sensitive: non-salt-sensitive patients among the three ACE genotype groups. However, the ratio was significantly larger in the haptoglobin 2-1 phenotype group than in the 2-2 group. CONCLUSIONS: The salt sensitivity of blood pressure was associated with the haptoglobin phenotype, but was not associated with the ACE genotype. However, the response of plasma renin activity to salt restriction was different according to the ACE genotype.

Adult↗

PubMed1993

Basal high blood pressure cosegregates with the loci on chromosome 1 in the F2 generation from crosses between normotensive Wistar Kyoto rats and stroke-prone spontaneously hypertensive rats.

We investigated the linkage between high blood pressure (BP) and microsatellite genotypes in the independently produced F2 progenies between Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) at the age of 2.5, 3 and 5 months before salt loading and after 2 month salt loading. In 2.5, 3 and 5 month-old male and female F2 progenies, blood pressure was significantly higher in homozygotes of the SHRSP allele at the two loci on rat chromosome 1, leukosianine (LSN) and myosin light chain (MYL2), than those of heterozygotes or WKY homozygotes. However, this strong cosegregation was attenuated after salt loading for 2 months. Basal (non salt-loaded) blood pressure strongly cosegregates with the loci on rat chromosome 1 and, therefore, putative gene(s) in this region contribute to the development of basal high blood pressure in SHRSP.

Aging↗

PubMed1993

A new genetic locus cosegregating with blood pressure in F2 progeny obtained from stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats.

BACKGROUND: Segregation studies using genomic polymorphisms on F2 progeny obtained from hypertensive rat models showed that a putative hypertensive gene is located close to the angiotensin converting enzyme (ACE) gene. However, it was suggested that additional major genes should contribute to the pathogenesis of hypertension. METHODS: F2 rats were obtained from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats of Izumo colony. Blood pressure was measured with a photoelectronic oscillometric tail-cuff method before and during salt loading. Genomic DNA was extracted from livers and digested with HaeIII or Rsal. DNA fingerprinting was performed with 26 32P-labelled human variable number of tandem repeats markers. RESULTS: Eighty-seven fingerprint bands polymorphic between SHRSP and WKY were obtained. When the distribution of these bands in the F2 progeny was studied, one fingerprint band (1/MCT96.1) showed a distorted distribution between the high- and low-blood pressure subpopulations of the F2 rats, suggesting that the band cosegregated with blood pressure. When blood pressure was compared between the F2 rats with [(+) rats] and without [(-) rats] the 1/MCT96.1 band, it was found that (-) rats had significantly higher basal and salt-loaded blood pressures than (+) rats. The 1/MCT96.1 locus was also shown to have no positive linkage with the ACE locus. CONCLUSION: The present study showed that examination of the allele distribution between subpopulations with extreme phenotype can be used in the screening of loci cosegregating with blood pressure. Furthermore, a locus not in the ACE region, showing cosegregation with blood pressure in F2 progeny from SHRSP and WKY rats, was found.

Animals↗

PubMed1993

Intralymphocytic free calcium and magnesium in stroke-prone spontaneously hypertensive rats and effects of blood pressure and various antihypertensive agents.

1. Free Ca2+ ([Ca2+]i) and Mg2+ ([Mg2+]i) were measured in peripheral lymphocytes from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) at the age of 5, 7 and 17 weeks, from various antihypertensive agents-treated SHRSP, and from secondary hypertensive WKY. 2. At the age of 5 weeks, no difference was observed in systolic blood pressure (SBP), or lymphocyte [Ca2+]i and [Mg2+]i between SHRSP and WKY. At the age of 7 or 17 weeks, SBP and [Ca2+]i of SHRSP were significantly higher than in WKY, and at the age of 17 weeks, [Mg2+]i of SHRSP was significantly lower than in WKY. Further, [Ca2+]i or [Mg2+]i was positively or negatively correlated to SBP, and [Mg2+]i was negatively correlated to [Ca2+]i. 3. SBP of SHRSP fell significantly after antihypertensive treatment with calcium antagonist, angiotensin-converting enzyme (ACE) inhibitor or hydralazine for 40 days. [Ca2+]i was significantly lower in calcium antagonist and hydralazine groups, and tended to be low in ACE inhibitor group. These four groups showed no difference in [Mg2+]i. 4. After 40-day administration of NG-nitro-L-arginine (L-NNA), WKY developed severe hypertension, but there were no significant differences in lymphocyte [Ca2+]i and [Mg2+]i between the L-NNA treated and non-treated groups. 5. These results suggested that increased lymphocyte [Ca2+]i and decreased [Mg2+]i observed in SHRSP are not only secondary to hypertension but possibly related to a basic genetic abnormality of divalent cation handling.

Animals↗

PubMed1992

Liver mevalonate 5-pyrophosphate decarboxylase is responsible for reduced serum cholesterol in stroke-prone spontaneously hypertensive rat.

Spontaneously hypertensive rat (stroke-prone) (SHRSP) has an interestingly low serum cholesterol level due to a reduced biosynthesis of cholesterol in the liver (Iritani, N., Fukuda, E., Nara, Y., and Yamori, Y. (1977) Atherosclerosis 28, 217-222). In this study, we examined the mechanism underlying the reduction of hepatic cholesterol biosynthesis in the rat. Our initial findings in SHRSP, as compared with normotensive Wistar Kyoto rat (WKY), showed that 1) the incorporation of [14C]acetate into cholesterol in the liver slices was markedly less, 2) 3-hydroxyl-3-methylglutaryl (HMG) CoA reductase activity was not reduced, and 3) the incorporation of [3H]mevalonic acid into both cholesterol and squalene was significantly less. The above initial findings suggested that the reduction in the hepatic cholesterol biosynthesis took place in one or more enzymatic processes starting with mevalonic acid and continuing to squalene. When the incorporation of [3H]mevalonic acid into phosphomevalonate derivatives was studied using an ion exchange column, only the radioactivity incorporated into isopentenyl-pyrophosphate (isopentenyl-PP) was less in SHRSP. Furthermore, the specific activity of diphosphomevalonate (mevalonate-PP) decarboxylase in the liver-soluble fractions was reduced 50% in SHRSP as compared with WKY. Kinetic studies using liver crude extracts indicated a lower Vmax value in SHRSP (SHRSP, 0.47; WKY, 2.05 nmol/min/mg), and an unchanged Km value (SHRSP, 18.2; WKY, 19.6 microM). The activity of mevalonate-PP decarboxylase was also found to be reduced in other tissues, including the brain, testis, small intestine, and cultured vascular smooth muscle cells. From the above observations, we concluded that the lower activity of mevalonate-PP decarboxylase was responsible for the reduced cholesterol biosynthesis in the liver of SHRSP.

Acetates↗

PubMed1992

Morphological differentiation of endothelial cells co-cultured with astrocytes on type-I or type-IV collagen.

In this study bovine aortic endothelial cells were co-cultured with astrocytes from fetal Wistar Kyoto rats. Endothelial cells growing on type-I collagen, co-cultured with astrocytes, showed various stages of development. Although some cells appeared to be mature, horseradish peroxidase penetrated within 1 min of incubation through the intercellular junctions of these endothelial elements maintained on type-I collagen. In contrast, endothelial cells on type-IV collagen, co-cultured with astrocytes, were well developed; their intercellular junctions were well established, and plasmalemmal vesicles reduced in number. As a result, horseradish peroxidase was unable to penetrate through the endothelial cells grown on type-IV collagen and co-cultured with astrocytes because of the reduced extent of the junctional and vesicular transport. These findings reveal that (1) type-IV collagen is essential for the differentiation of endothelial cells, (2) endothelial cell-astrocyte interactions occur during co-culture, and (3) endothelial permeability depends on astrocyte-produced factors, in addition to type-IV collagen.

Animals↗