The intracoronary injection of thromboxane A₂, in a dose of 0.06 to 1.3μg in terms of norepinephrine, induced in rabbits, in a dose dependent manner, mild to severe ischemic myocardial changes, i. e., an angina pectoris-like response, variant angina-like response, myocardial infarction and sudden cardiac death.
EG626 given to rabbits intravenously in doses of 0.1-1.0mg/kg prevented significantly the myocardial infarction induced by an intracoronary injection of 807±66.8ng of thromboxane A₂.

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Morphogenesis of atherosclerosis and vascular lesions as the cause of thrombus formation in the arteries of the lower limb were investigated histologically and immunohistochemically.
Fibrocellular intimal thickening of the arteries in the newborn was localized in bifurcaitons of the femoral artery and slightly involved non-bifurcated segments of the artery within two years. The pronounced and laminated intimal thickening which was frequently observed in hypertensives resulted from repeated proliferation or growth of the intimal tissue. It seems probable that various kinds of stimuli repeatedly affect on the arterial wall leading to make a reactive or regenerative proliferation of the intimal cells and endothelial cells.
Infiltration of plasma constituents into the intima as slight as being not able to detect until using with an immunohistochemical method was diffusely observed in the fibrocellularly thickened intima.
There were preferential sites where severe infiltration of blood plasma lipids and proteins into the intima occurred. Appearances with blood plasma, extracellular lipid and foam cells were sometimes seen at edge of the thickened intima and in the interlayer junctions between formerly and newly established layer of the intima. Markedly enhanced permeability in these special sites may be drove by two kinds of forces. One is a force splitting junctions between the thickened intima and media and also between each intimal layer, due to contraction of smooth muscle cells which are running in different directions in each layer of the arterial wall. The others are hemodynamic factors, i. e. turbulence of blood stream and increased tensil force occurring on shoulder of the thickend intima. These forces affect on the endothelial cells and injure them.
In the femoral and popliteal arteries thrombi were formed on segments involved with severe atherosclerosis and with accumulation of many foam cells beneath the endothelium. Thrombosis in the peripheral arteries below the knee was found on the intima showing fibrocellular thickening or edema. In the proximal arteries tear or split of superficial layer in the atherosclerotic intima plays an important role in thrombogenesis. There are many various causes of the tear being able to be considered, for instance, 1) a large tensil force acting on shoulder of the thickened intima, 2) structural discontinuity at abutting areas between different layers of arterial wall, and 3) histolytic effects of foam cells and the blood plasma accumulated in the intima, presumably effects of some unknown active substances derived from foam cells or contained in the blood plasma.

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Regarding to the pathogenesis of renal arteriolar hyalinosis in diabetic nephropathy, we reported that glomerular circulatoly disturbance and Dysorie's theory (Schürmann and McMahorn, 1933) play on important parts in it's occurrence. Because, we found that the renal arteriolar hyalinosis most commonly occurred at vas. afference, it's near part and intraglomerular branches of vas. afference. This fact strongly suggested that the arteriolar hyalinosis is caused by the hemodynamic alteration due to circuratoly disturbance which might be taken place abruptly at the peripheral portion of intraglomerural afferent branches. But the genesis of this circuratloy disturbance is still unknown. The purpose for making clear on it, we examined that correlation between the morphology of diabetic glomerular lesion and arteriolar lesion to some clinical factors, duration of diabetes, hypertension, condition of DM-controle, proteinuria, serum creatinine level, rate of PSP-15 min., rate of inuline and PAH-clearance on 65 samples of kidney were obtained by autopsy. Result: 1) Duration of diabetes mellitus correlated to glomerular and arteriolar lesion. 2) Hypertension more correlated to arteriolar lesion than glomerular lesion. 3) Correlation is not found between FBS-controle in admission to glomerular lesion and arteriolar lesion, but the observations on samples of Brittle's type and diabetic coma, we found that poor controle of blood sugar level have had influence on arteriolar lesion. 4) Proteinuria is apt to precede to glomerular lesion in light microscopic finding. 5) Rate of PSP-15 min. and inuline and PAH-clearance correlated to glomerular and arteriolar lesion, but more strongly correlated to later one.

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Elevated blood cortisol level and urinary 17-OHCS output coincided with manifestation of atherosclerotic lesions in chronic hypovitamin C animals has been reported. In the present studies, relationship of ascorbic acid and adrenal function or serum lipids on hypovitamin C animal and on atherosclerotic patients with hyperlipidemia were investigated.
Guinea pigs weighing about 300 grams were divided into four experimental groups as group 1 fed with normal diet, group 2 fed with scorbutogenic diet, group 3 with scorbutogenic diet added 1% cholesterol and 5% corn oil by weight and group 4 fed with similar diet of group 3 and administered 25mg of ascorbic acid everyday, for four weeks. Further, each group was divided into two subgroups as the control and the steroid administered which was given 20mg/kg of hydrocortisone subcutaneously every day during experimental period and designated as “+ST”.
On the patients with hyperlipidemia was sub-divided into lipoprotein phenotypes according to WHO criteria and blood ascorbic acid and plasma cortisol level was estimated.
Blood ascorbic acid content in the group 2+St and 3+ST were declined as compared with the each control. Increase of serum lipids by steroid administration were observed in the group 1+ST and 2+ST, while steroid administation was suppressed an increase of serum cholesterol by cholesterol feeding in group 3+ST and 4+ST. See table 1. Total acid mucopolysaccharide and hydroxyproline in the aorta were decreased when hydrocortisone were administered as shown in Fig. 1. Atherosclerotic change was found in the proximal portion of the aorta of group 2 and 3, although, no sclerotic change were observed in the aorta of steroid administered animals. Histological observation revealed that diminution of the interstitial tissue between the elastic lamella in the aorta of steroid administered animals. This findings supports the results of mucopolysaccharide and hydroxyproline determination.
Significant high incidence of low ascorbic acid content in the blood and high plasma cortisol level in the patients with type IIa as compared with other types of hyperlipidemia. See Fig. 2.
These observations suggests that administration of hydroxycortisone causes an increase of serum lipids and declein of blood ascorbic acid, but not enhance atherosclerotic process. In some hyperlipidemia, particularly in type IIa, chronic hypovitamin C might be a pathogenic factor of hyperlipidemia.

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Studies were made on the features of atheromatous lesions in the coronary artery of Wistar strain male rats, induced by the oral vitamin D₂ and lipid-rich diet treatment.
Administration of vitamin D₂ (40, 000IU/rat/day) for five consecutive days plus 1% cholesterol and 0.2% cholate diet (commercial rat chow: Funabashi Nojo, F-2) feeding for three weeks induced extensive lipid deposition and fibroblastic proliferation principally in the intima of coronary arteries, while no lipidosis occurred in the aorta. Reducing the dose of either vitamin D₂ or cholesterol decreased the incidence of atheromatous lesions. Vitamin D₂ alone evoked initially stretching and degeneration of the internal elatic membrane and reduction in the thickness of the media (Day-2-5), and later intimal thickening with progressing increase in the thickness of the arterial wall. In cholesterol fed animals vitamin D₂ induced lipid infiltration, which was observed as sudanophilia in the media on Day-8, and finally remarkable granular lipid deposition predominantly in the thickened intima, being associated with the appearance of foam cells and some fibroblastic proliferation (Day-21). Calcification was not observed in the coronary arterial wall throughout the experimental period, while clear calcified zones were demonstrated in the media of aortas, suggesting that calcification is not responsible for lipid deposition.
Addition of coconut oil 30% in the diet or fructose 10% in the drinking water instead of cholesterol and cholate failed to induce the intimal lipid deposition. Agarose gel electrophoresis of serum lipoproteins showed that the increase of preβ-LP and/or fast-migrating β-LP (β-VLDL?), but not of chylomiscron is related to the formation of these atheromatous lesions in this model.
These results indicate remarkable resemblance in the features between these experimental lesions and early human atherosclerosis. It is, therefore, suggested that this model is useful for preliminary screening of anti-atherogenic agents.

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Ligation or clipping of bilateral renal arteries caused angionecrosis, tissue edema and severe hypertension in the dogs and rats. The syndrome is identical to human malignant hypertension. These experiments lead a concept of a release of humoral agent(s) inducing vascular lesions from involved kidneys.
The possibility of the concept was studied in patients with malignant hypertension. Plasma renin activity (PRA), serum LDH, GOT and GPT on admission were compared between patients with malignant hypertension and hypertension accompanying chronic renal failure without papilledema. There was no difference of serum creatinine level between the two groups of the patients. Diastolic blood pressure, PRA, LDH and GOT were significantly higher in patients with malignant hypertension than in those without them. When one renal artery of rats was completely ligated, changes in blood pressure and an occurrence of angionecrosis were studied in comparison with those in unilaterally nephrectomized arts. On the 7th day after the ligation blood pressure was significantly elevated and reached the level of 150mmHg or more. Fibrinoid necrosis was observed in the mesenteric arteries in the experimental animals, but not in the controls. The ligated kidneys showed coaggulation necrosis.
Lysosomal fraction obtained from rat kidney cortex by subcellular centrifugation method of Shibko and Tappel showed high renin activity. The lysosomal fraction, when injected into bilaterally nephrectomized rats, caused increase in blood pressure, fibrinoid necrosis of the arterioles, tissue edema and increased vascular permeability in the experimental animals.

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Partial purification and characterization of angionecrosis (fibrinoid necrosis) factors localized in hog kidney lysosome was attemted.
The subcellular fractionation was performed by using of differential centrifugation and osmotic shock treatment with enzyme profile determination. The purification procedure consisted of chromatography of the protein fraction on concanavalin A affinity chromatography, sepharose 6B gel filtration and Biogel P-100 gel filtration in this order.
Non-affinity fraction from concanavalin A affinity column showed no pressor activity, however it produced angionecrosis of the bilaterally nephrectomized rats and increased vascular permeability of rabbit skin. Assay for angionecrosis and vascular permeability activity at two steps of the gel filtration (sepharose 6B and Biogel P-100) showed that both activity did not run parallel, because the fraction containing the strong angionecrosis producing activity did not necessarily induce the very increased vascular permeability and contrarily the fraction of the strong permeability activity did not necessarily produce the severe angionecrosis.
These findings suggest that the angionecrosis producing factor seemed different from vascular permeability increasing factor.
By contrast the pressor effect of concanavalin A affinity fraction could not be dissociated from the angionecrosis and vascular permeability effect using gel filtration.

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Non-pressor renal vascular injurious factor was injected intra venously to bilaterally nephrectomized rats.
Striking features of endothelial cells in mesenteric and pancreatic arteries responsible for increased permeability, namely, the separations of intercellular junctions and denudation of endothelial layer were observed. In consequence, serous component and ferritin particles, rarely accompained by platelets, erythrocytes and polynuclear leukocytes penetrated into the media, in which fibrin deposits were focally exhibited.
Another study employed the procedure to perform unilateral nephrectomy and contralateral urethral ligation and to remove the ligation 24 hours after the intravenous injection of renal cortical extract so as to privide long survival of rats.
Panarteritis was observed 5-7 days after the renal cortical extract injection and it was sometimes accompained by fibrinoid degeneration.
Proliferation of elastic fibers of the intima and cellulofibrous thickening of the media were observed in some arteries 1-2 months after the renal cortical extract injection.
These changes occured independently from hypertension, immunological factors and abnormality of BUN and urine protein levels.

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In order to clarify the roll of intrinsic renin in the development of hypertensive vascular lesions, plasma renin activity (PRA) and pathological findings were studied in two types of renovascular hypertension in rabbits.
I. Short-term experiment.
Hypertension was produced by constriction of left renal artery with an intact right kidney (two-kidney hypertension, Group A, 33 animals), and with right previous nephrectomy (one-kidney hypertension, Group B, 33 animals). Seven days after renal artery clipping, colloidal carbon was injected intravenously, and after one hour animals were sacrificed and examined light microscopically. PRA, serum Na, serum K, urea-N and hematocrit were determined before and after the operation.
Hypertension developed in both A and B groups similarly. Increased PRA, hypokalemia and increased hematocrit value were observed in animals of group A only. PRA was increased in about half of animals of group A, but it remained unchanged or rather reduced in animals of group B. Acute vascular lesions were defined as fibrinoid necrosis of the small arteries and arterioles, insudation of carbon particles into the arterial wall, or lesions resembling periarteritis. The vascular lesions were found in 19 (57.6%) of 33 animals of gloup A and in 17 (51.5%) of 33 animals of group B. There was no difference in incidence and histological features of the vascular lesions between the two groups. The presence or absence of the vascular lesions did not depend upon the level of blood pressure in both groups. Within the group A, there was no significant correlation between PRA and development of the vascular lesions.
II. Long-term experiment.
Twenty animals of two-kidney hypertension (Group A) and twenty-one of one-kidney hypertension (Group B) were observed for twenty weeks after the renal artery costriction. Hypertension developed similarly in both groups. In animals of group A, increased PRA, hypokalemia and increased hematocrit values were seen. But in animals of group B, PRA was not increased.
Eight (38%) out of twenty-one animals of group B died, and all these eight animals had cerebral haemorrhage. None of group A animals died. Histologically fibrinoid necrosis was seen in all animals that died and had cerebral heamorrhage, but in another animals it was seen in only one of group A animals. Another chronic vascular lesions were seen frequently in both groups. There was no significant difference in blood pressure and in another parameters between animals that died and survived.
It is concluded that the vascular lesions and cerebral haemorrhage can develop independently of PRA or level of blood pressure.

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Since the first discovery by Winternitz et al, various investigators have indicated the presence of renal substances inducing necrotic arterial lesions. Because of the similarity of the vascular lesions to those found in cases of malignant hypertension and cerebro-vascular disease, it has been suggested that the substances are mediators of arterial lesions in hypertensive vascular disease.
The present paper deals with a vascular permeability factor of renal origin other than renin, and the main purpose is to describe its character and method of purification.
A vascular permeability factor was purified from the kidney extract of normal rats by estimating dye permeability in the skin vessels of rabbits as a measure of its enhancement of vascular permeability. The purification procedure included Sephadex G-50 chromatography and hydroxyl apatite chromatography. Throughout two chromatographic steps, specific activity of permeability factor increased approx. 50 times.
The factor was not dialyzable and its molecular weight was approx. 20, 000. It appeared to be different from renal proteases including renin which was well known as renal vascular injury factor, due to its heat-stable nature: Dye permeability activity was not eliminated by heat treatment at 100°C for 10min., whereas the activity of renin and protease was completely inactivated by the same treatment.
The duration of the factor's effect was longer than that of histamine, and the degree of permeability activity induced by the factor reached a maximal level at 30-60min. and subsided at 120min. after the injection.
Permeability factor not only induced dye permeability in rabbit's skins tested but also resulted in the retention of ascites in the same animals. Effusion inducing activity of the factor was considered a manifestation of enhanced vascular permeability caused by the factor via the systemic circulation route.
Although the intradermal injection of the factor could not induce so-called angionecrosis of small arteries in the skin sites where the factor was injected, some early, degenerative changes of smooth muscle cells and endothelial cell in the skin arteriole were observed.
Thus, the present paper revealed the presence of renal vascular permeability factor other than renin and its character. The role of this vascular permeability factor for the development of arterial lesions was discussed.

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The relationship between the histologic change of arterial wall such as intimal thickening, initmal cell proliferation, inflammation and thrombus formation discussed on 44 human aortas.
1) The frequency of thrombus formation of human aortas increased in proportion to intimal thickening in the cases of intimal thickness: <200μ10%, 201-300μ22%, 301-400μ30%, 401-500μ38%.
2) The number of intimal cells per 215, 5μ² of macroscopically normal intimal surface, abdominal aorta is lesser in abdominal aorta than that of thracic aorta. The number of intimal cells reached the peak at 20-30 years old and therafter its number decreased with aging.
3) The rate of thrombus formation on inflamed aortic intimal areas was 36% and more increased tendency was found sclerotic lesions accompanied with inflammation.
4) The detachment of endothelial cells and exposure of subendothelial tissue to blood stream are the condition indispensable for thrombus formation and subendothelial edema would contribute to the endothelial degeneration.

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