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PubMed1977

The effect of sex hormones on glycosaminoglycan content of canine aorta and coronary arteries.

Hyaluronate (HA), heparan sulfate (HS), dermatan sulfate (DS) and isomeric chondroitin sulfates (CS) were measured in vascular walls of 9-10 months old normal and hypophysectomized female beagles treated with sex hormones. Following hypophysectomy the animals were maintained for 8 weeks without any hormonal replacement therapy and then they were exposed for 3 weeks to parenteral treatment with sex hormones. One group received twice weekly 25 mg testosterone, another group was given the same amount of progesterone, and a third group received on day 1 and day 14, estrogens in 2 injections, consisting of a mixture of 10 mg short-acting estradiol-17-phenylpropionate and 2.5 mg long-acting estradiol benzoate. After 11 weeks all animals were sacrificed, coronary arteries and aortas were immediately removed and the latter were divided into three segments: arch, thoracic and abdominal. Removal of the pituitary led to a reduction of the HA content in the aortic arch and thoracic segment, but coronary arteries and abdominal aorta were not affected. The main consequence of hypophysectomy both in the entire aorta and in coronary arteries was a sharp reduction of the sulfated glycosaminoglycan (GAG) content. All three hormones produced a modest rise in the HS content of coronary arteries. A more definite response was seen in the thoracic aorta where each of the three hormones raised the low DS content to normal levels. Concerning the effect of sex hromones on aortic GAG other than DS, TESTOSTERONE RAISED THE CS content towards normal in thoracic and abdominal segments, while estrogen by doubling the normal HA concentration was particularly potent in the abdominal aorta. It is conceivable that the different sensitivity of various segments of aorta and coronary arteries to sex (and other) hormones in terms of regulating GAG metabolism may prove to be of relevance to the uneven distribution of lesions in degenerative vascular disease.

Animals↗
PubMed1977

The dietary regulation of stearyl coenzyme A desaturase activity and membrane fluidity in the rat aorta.

Numerous studies have demonstrated that alterations in membrane composition or fluidity are often associated with alterations in the properties of membrane-bound enzymes. In order to obtain membranes of varying fluidity, rats were fed diets that were either fat-free or supplemented with 15% safflower oil, and two properties associated with aorta and liver microsomal membranes were selected for study: stearyl CoA desaturase activity, and fluidity as monitored by fatty acid composition and microviscosity (measured by fluorescence depolarization). If fluidity directly modulates desaturase activity, one would predict that a low fluidity would stimulate the desaturase activity. Ten times more desaturase activity is present in aorta microsomes from rats on a fat-free diet than in microsomes from rats on a safflower oil supplemented diet. However, on the fat-free diet, these aorta microsomes were more fluid than those of rats fed safflower oil supplemented diet. The fluidity of liver microsomal membranes was not altered in response to diet, despite significant changes in desaturase enzyme content. The contrasting evidence presented here suggests that no correlation exists between desaturase enzyme activity and membrane fluidity in the two tissues studies. We have demonstrated that the aorta has appreciable capacity to desaturate stearyl CoA and that dietary manipulation causes significant changes in aorta membrane fluidity that may be of sufficient magnitude to affect the overall metaboism of aorta cells.

Animals↗
PubMed1977

Possible role of endogenous catecholamines in the contractions induced in rabbit aorta by ouabain, sodium depletion and potassium depletion.

Effects of ouabain, Na+ depletion and K+ depletion on the tension development of rabbit aorta were studied. Contraction in the strips was induced by ouabain and Na+-free solution substituted with Li+, tris or sucrose. The contractions were rarely seen under alpha-adrenergic blockade, in reserpinized aorta and mechanically denervated aorta. Contractions induced by norepinephrine were potentiated by Na+ depletion, K+ depletion and ouabain. Contractions induced by high K+ solution were also potentiated by Na+ depletion and ouabain. The potentiation in Li+ solution, K+-free solution and with ouabain was not seen under alpha-adrenergic blockade, in reserpinized aorta and denervated aorta although the potentiation by tris and sucrose solutions was still observed. These data suggest that Na+ depletion, K+ depletion and ouabain release endogenous catecholamines which affect the contraction of the vascular smooth muscle of rabbit aorta.

Animals↗
PubMed1977

Metabolic intermediates, enzymes and lysosomal activity in aortas of spontaneously hypertensive rats.

Metabolic intermediate levels, glycolytic and Krebs cycle enzyme activities and lysosomal acid hydrolase activities were measured in aortas of spontaneously hypertensive (SHR) versus normotensive (WKY) rats. In the hypertensive aortas the level of lactate, the ratio of lactate to glucose and of lactate to malate was higher in the SHR than WKY aortas. In the hypertensive aortas the obvious shift of metabolism toward higher rate of glycolysis was associated with decreased activity of malate dehydrogenase and espically of lipoamide dehydrogenase. The latter is an essential compoenent of the alpha-ketoglutarate and pyruvate dehydrogenase enzyme complexes and it appears that these complexes are among the sites of arterialmetavolism which are primarily altered by the elevated blood pressure, resulting in increased production of lactate. The activity of the marker lysosomal enzyme N-acetyl-beta-glucosaminidase was unequivocally elevated in the hypertensive aortas. The activity of beta-glucuronidase exhibited incogruous differences between the SHR and WKY aortas and the activity of aortic acid phosphatase did not differ in the two rat strains. The results are discussed in relation to arterial injury, permeability, and atherogenesis.

Acetylglucosaminidase↗
PubMed1979

Carnitine palmitoyltransferase activity in mitochondrial fractions isolated from aortas of rabbits fed cholesterol-supplemented diets.

beta-Oxidation of long-chain fatty acids increases many-fold in atherosclerotic aortas; this may be due to an increase in the activity of the mitochondrial enzyme hexadecanoyl-CoA: carnitine O-hexadecanoyltransferase EC 2.3.1.23 (trivial name: carnitine palmitoyltransferase, CPT). To investigate this possibility, an assay for arterial CPT was developed and used to measure CPT activity in mitochondrial fractions isolated from aortas of rabbits fed high-fat (HF) or high-fat plus cholesterol (HFC) supplemented diets. The arterial CPT assay was linear with respect to mitochondrial protein between 0.03 and 0.30 mg and assay time between 3 and 12 min. Maximum CPT activity was observed at concentrations of palmitoyl-CoA between 5 and 25 micron, higher concentrations of palmitoyl-CoA inhibited CPT activity. CPT activity was measured in mitochondrial fractions isolated from aortas of rabbits fed the HFC-supplemented diet for up to 48 days. No visible lesions were observed in aortas of rabbits fed HFC-diet for 3,9, or 21 days, however, by 48 days atheromatous lesions covered in excess of 60% of the intimal surface of the aorta. No lesions were visually observed in aortas of rabbits receiving the HF-diet. Despite the development of gross atherosclerotic lesions, there were no changes in CPT activity observed that could account for a dramatic increase in fatty acid oxidation. It is concluded that the increase in beta-oxidation of long-chain fatty acids in atherosclerosis is not attributable to an increase in CPT activity.

Acyltransferases↗
PubMed1976

Observations on the treatment of dissection of the aorta.

The results are presented of treatment in twenty-three patients with dissection of the thoracic aorta, in four of whom it was acute (less than 14 days' duration), and in nineteen chronic (more than 14 days' duration). Sixteen patients had Type I and II dissection (involving the ascending aorta) and five Type III (descending aorta at or distal to the origin of the left subclavian artery); in two, dissection complicated coarctation of the aorta in the usual site. Thirteen patients had aortic regurgitation. Three of the patients with acute dissection were treated medically; two, both with Type I dissection, died, and the third, with Type III, survived. The remaining acute patient was treated surgically and also died. Of the patients with chronic dissection, eight were treated medically and eleven surgically. None of the medical group died in hospital; three died between 3 months and 1 year, and five have survived from periods of 12-72 months. Eleven patients with chronic dissection were treated surgically; four died in hospital at or shortly after operation; and the remaining seven lived for periods of 12-84 months. The presentation, indications for surgical treatment and results are discussed. It is concluded that surgical treatment of chronic dissection may carry a higher initial mortality than medical, but that there may be slightly better overall long term results in the former. As this series was not selected randomly, because patients with complications were selected for surgery, and there are only a few patients in each group, the results do not permit firm conclusion regarding the relative merits of medical and surgical treatment. It is suggested that all patients should initially be treated medically but that surgical treatment should be considered if the dissection continues, if aortic regurgitation is severe, if an aneurysm develops or enlarges, if cardiac tamponade develops or there is evidence of progressive involvement of the branches of the aorta. Attention is drawn to the important syndrome of chronic dissecting aneurysm of the ascending aorta with severe aortic regurgitation which requires definitive surgical treatment and aortic valve replacement. The importance of adequate visualization of the origin and extent of the dissection as a preliminary to surgical treatment is stressed.

Acute Disease↗
PubMed1976

Characterization of lipids associated with macromolecules of the intercellular matrix of human aorta.

Macroscopically lesion-free parts of human aortas with no or light lesions (group I) and advanced atherosclerotic lesions (group II) were submitted to a series of successive extractions in order to "solubilize" all the macromolecular components of the arterial wall ("chemical dissection"). Lipids were extracted with methanol-chloroform from all these macromolecular fractions and analyzed for cholesterol, triglycerides, phospholipids. The fatty acid composition of the separated fractions was determined by GLC. The lipid composition and fatty acid spectrum of the macromolecular fractions of group I and group II aortas was compared. Total lipids increased in the freely extractable ("non associated lipids, approximately 78% of total) fraction as well as in the fraction "associated" with collagen and elastin. Free and esterified cholesterol increased also both in the "freely extractable" and in the collagen-elastin-associated lipids", approximately 78% of total) fraction as well was higher (+ 100%) than that of free cholesterol (+ 60%). Triglycerides increase also by 15 to 70% in all fractions except in the elastin-associated fraction. Free fatty acids increased by 40 to 400% in all extracts associated with macromolecular fractions but not in the "freely extractable" fraction where they decreased. Phospholipids show less marked variations (approximately less than 10%) and decrease in the elastin associated lipids of group II aortas. The fatty acid spectrum of group II lipids associated with macromolecules differs from that of group I. There is a relative increase of longer chains (C greater than 18, especially 20:1 and 20:2 acids). No such increase in the "long" fatty acids was seen in the "freely extractable" lipid fraction. Elastin isolated from group II aortas is significantly enriched in total lipids, cholesterol (free and esterified) and free fatty acids and contains the widest spectrum of fatty acids (from 11:2 to 22:1) with a significant fraction of total fatty acids as "odd" carbon chains. There appears to be a correlation between the decrease of triglyceride-bound fatty acids and the increase of free fatty acids. The free fatty acid concentration exceeds both in group I and II aortas the concentration of fatty acid esters. This increase in free fatty acids "associated" with intercellular matrix macromolecules and especially with elastin may be the result of an increased hydrolysis of esters and/or a decreased esterification in advanced atherosclerotic aortas. The accumulation of long chain and "odd" fatty acids in elastin may be an important factor in its accelerated degradation during the atherosclerotic process.

Aorta↗
PubMed1977

Occlusion of the abdominal aorta in a 29-year-old patient.

Following a period of two years with gradually increasing dyspnoe, the patient, a 29-year-old man, suddenly developed acute respiratory distress. On admission to hospital, blood pressure was 260/110, and there were no femoral pulses. Cine-angiography of the aorta revealed a total occlusion from the level of the first lumbar vertebra to the renal arteries. An extensive collateral circulation was visualized. Kidney function was normal. At operation, the aorta was as hard as stone, but the calibre was normal from the diaphragm down to the renal arteries. A dacron graft was inserted, end-to-side between the thoracic aorta and the abdominal aorta distal to the inferior mesenteric artery. Postoperatively, the systemic and ankle blood pressure became near normal. The aetiology of the aortic changes remains unknown. Several possibilities are considered, among them abdominal aortitis and cystic necrosis of the media. Coarctation of the abdominal aorta is less likely, as no narrowing of the aorta was seen at operation.

Adult↗
PubMed1976

Atherosclerosis of the aorta in five towns.

Fatty streak was always present in both the thoracic aorta and the abdominal aorta in the youngest subjects studied (aged 10-14 years). Fibrous plaque was present in a small proportion of these young subjects, but a rapid increase in prevalence occurred as early as the fourth decade. Complicated and calcified lesions appeared as early as the age of 20-25 years but a rapid increase in prevalence was seen after age 40 for complicated lesions and after age 50 for calcified lesions. There were differences in the prevalence of severe lesions among the five towns. There was little increase in the extent of atherosclerosis in the thoracic aorta before the age of 40 and in the abdominal aorta before the age of 20. The increase was more rapid after those ages. When atherosclerosis had affected about 50% of the intimal surface of the thoracic aorta and 70% of the intimal surface of the abdominal aorta, the increase slowed down considerably. In contrast to other types of lesion, the extent of fatty streak increased only up to 30 years of age, when it occupied 25-30% of the intimal surface. Then it declined and in the older age groups did not exceed 4-5% in men or women. The extent of fibrous plaque and complicated lesions was at all ages greater in men than in women, while the extent of fatty streak and calcified lesions in older age groups was greater in women. There were marked differences in the extent of atherosclerotic lesions in the five towns.

Adolescent↗
PubMed1976

Successful interposition synthetic graft between aorta and right coronary artery. Angiographic follow-up to sixteen months.

A knitted Dacron filamentous vascular prosthesis, 4 cm. long and 3.5 mm. in diameter, was used as an interposition graft between the aorta and right coronary artery in a 65-year-old woman on Oct. 25, 1974. The prosthesis was used to transplant the right coronary artery incident to removal of a saccular aneurysm if the ascending aorta. Concomitant mitral valve replacement and tricuspid annuloplaty were performed. The graft was demonstrated patent by angiograms 2 weeks, 7 months, and 16 months after the operation, and the patient continues to be clinically well 17 months postoperatively. The literature records the successful use of aorta-coronary Dacron prostheses in 2 other patents, both children with coronary anomalies. One of these grafts closed after a while: the second was demonstrated patent by angiograms 8 years after implantation. These cases demonstrate that prostheses can function in the aorta-coronary position, and the reports of saphenous vein failures indicate the need for a reasonable substitute when a patient's saphenous veins are absent or inadequate. In all 3 cases, the prostheses were quite short and were used as interposition grafts between the ascending aorta and the proximal end of the coronary artery. Our review did not reveal successful use of a synthetic graft for aorta-coronary bypass.

Aged↗
PubMed1978

Regions of constantly increased plasminogen activator activity along the intima of the normal aorta.

Histochemical studies of the aorta in newborn, young, and adult rats showed that the intima in the branching regions and at the beginning of the branches has a constantly increased plasminogen activator activity in comparison with the nonbranching regions. The aortic valve also shows constantly increased activator activity. The intimal activator activity is variable in the nonbranching regions, depending on the age and the anatomical area of the aorta. In young rats (20--30 days), the overall plasminogen activator activity in the aortic intima is higher than in adult rats (2--4 months), while the activity is variable in newborn rats. The intimal activator activity is generally higher in the thoracic aorta than in the abdominal aorta (in the nonbranching regions). The aortic wall has a low plasmin inhibitor capacity. The pattern of the endothelial plasminogen activator activity at different ages and anatomical areas of the aorta, in combination with the corresponding pattern of the aortic endothelial cell turnover, gives valuable information about the mechanism(s) of the production and normal (nonstressed) release of the endothelial plasminogen activator.

Aging↗
PubMed1977

Leucine and isoleucine as in vitro precursors for lipid synthesis by rat aorta.

The in vitro conversion of 14C-labeled leucine, isoleucine, and pyruvate to specific lipids was compared in rat aorta, diaphragm, anf fat pad. Total lipid specific radioactivity from all precursors was greatest in aorta. The ratio of label incorporated into polar lipids vs. neutral lipids by aorta was generally several-fold that incorporated by muscle and fat pad. The labeling of sterols in the aorta from 14C-leucine and pyruvate was equivalent. It is concluded that leucine may be a substantial precursor to polar lipids and to sterols in rat aorta.

Animals↗
PubMed1979

Two dimensional echocardiographic recognition of the descending thoracic aorta.

Two dimensional echocardiography was used to identify the descending thoracic aorta in 106 subjects. In 12 of these subjects, contrast injection techniques were used to identify this structure as it descended posteriorly adjacent to the atrioventricular groove. The course of the descending thoracic aorta was mapped using both the long axis and transverse axis views. The normal descending thoracic aorta (26 subjects) measured 10 +/- 1.4 mm/m2 during diastole. Unusual M mode echocardiographic patterns of the descending aorta may be confused with other disease states; they are clarified with the two dimensional study. The size and appearance of the descending aorta in different types of cardiovascular disease, including aortic aneurysm, in 80 patients are described. It is anticipated that two dimensional echocardiography will prove to be a useful method of studying patients with aortic disease.

Adult↗
PubMed1978

Regression of naturally occurring atherosclerotic lesions in pigeon aorta by intestinal bypass surgery. Early changes in arterial cholesteryl ester metabolism.

Early changes in cholesteryl ester metabolism of the aorta during the regression of naturally occurring atherosclerotic lesions in pigeon aorta by ileal bypass surgery were examined. Three months after surgery, there was a decrease (50%) in the content of cholesteryl esters in the aorta. Increases in the activity of cholesteryl ester hypdrolase in the lysosomal (P less than 0.05) and the supernatant (P less than 0.01) fractions of the aorta also occurred at this time. There were no differences in the activity of cholesteryl ester synthetase and in the plasma levels of cholesterol and triglycerides between the ileal bypass group and the controls. These results suggest that ileal bypass surgery decreases the level of cholesteryl esters in the aorta, probably because of enhanced cholesteryl ester hydrolysis.

Animals↗
PubMed1978

Lack of altered cyclic nucleotide phosphodiesterase activity in the aorta and heart of the spontaneously hypertensive rat.

DEAE-cellulose chromatography demonstrated that the levels of the individual cyclic nucleotide phosphodiesterases were unchanged in the aorta and heart of the spontaneously hypertensive rat as compared with the normotensive control rat. Three peaks of cyclic nucleotide phosphodiesterases activity were observed in both heart and aorta. Peak I enzyme hybrolyzed predominantly cyclic GMP while peak III enzyme hydrolyzed predominantly cyclic AMP. Peak II enzyme was less specific but hydrolyzed more cyclic GMP than cyclic AMP. The levels of phosphodiesterase activator in aorta and the responsiveness of peaks I and II from aorta and heart to activator were unchanged in the hypertensive rat. Therefore the decrease in cyclic AMP levels observed by others in aorta and heart of the spontaneously hypertensive rat were probably not due to altered phosphodiesterase activity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Effects of extracellular calcium on potassium and noradrenaline induced contractions in the aorta of spontaneously hypertensive rats--increased sensitivity to nifedipine.

Isolated preparations of the thoracic aorta from spontaneously hypertensive rats (SHR) and normotensive Wistar rats (NWR) were contracted by noradrenaline (NA) 1.8 X 10(-5)M, and potassium (K+) 127 mM, after 30 min. pretreatment in a Ca++-free medium. In both SHR and NWR aortae, the contractions were markedly reduced; no significant differences were found between the two types of vessels in Ca++-free medium. On addition of Ca++, the contractions were restored to a significantly greater extent in the NWR than in the SHR aortae. In the presence of nifedipine 7.2 X 10(-9)M, the response to Ca++ was significantly more reduced in the SHR than in the NWR preparations. Relaxation of NA and K+ contracted preparations was induced by wash-out of the contractile agents, by addition of nifedipine 2.9 X 10(-8)M, and by introduction of a Ca++-free medium. After wash-out of NA, relaxation was slower in SHR than in NWR vessels. Relaxation induced by nifedipine and Ca++-free medium was more complete in SHR than in NWR preparations. After wash-out of K+, relaxation was more rapid in NWR than in SHR aortae. Nifedipine and Ca++-free medium induced relaxation was more complete in SHR than in NWR preparations. The results suggest that in the SHR aortae contraction induced by NA and K+ is more dependent on extracellular Ca++ than is the response in the NWR preparations; the SHR vessels are also more sensitive to the relaxing effects of nifedipine.

Animals↗
PubMed1979

Kinetics of alpha-adrenoreceptor blockade by phentolamine in the normal and denervated rabbit aorta and rat vas deferens.

The rates of onset and offset of alpha-adrenoreceptor blockade by phentolamine (5 X 10(-7) M) have been studied on the normal and denervated rabbit aorta and rat vas deferens. Removal of the adventitia with its accompanying sympathetic nerve component results in an approximately threefold increase in the rate of onset of alpha-adrenoreceptor blockade by phentolamine in the rabbit aorta. The rate of offset of blockade by the antagonist on the aorta is likewise faster after the adventitia has been removed (approximately threefold faster for loss of 90% of the antagonist from the region of the receptors). This effect is not likely to be attributed to the absence of sympathetic nerve terminals since surgical denervation of the rat vas deferens has no effect on the kinetics of receptor blockade in this densely innervated organ. These data suggest that the adventitia of the rabbit aorta may serve as a diffusion barrier which limits the antagonist's access to, and efflux from, the region of the receptors. The dissociation constant of phentolamine (calculated from the equilibrium dose ratio) on the alpha-adrenoreceptor is unaltered by denervation in either tissue and is identical in both tissues. It is suggested that alpha-adrenoreceptors in the rabbit aorta and rat vas deferens are of a single type and are not significantly affected, with respect to antagonist affinity, by denervation.

Animals↗
PubMed1979

Age-related change in the reducible cross-link of human skin and aorta collagens.

Age-related changes in the reducible cross-links of soluble and insoluble collagens from the human skin and aorta were evaluated. Histidinohydroxymerodemosine decreased with age up to the fifth decade and then remained constant in the insoluble skin collagen but could not be detected in the insoluble aorta collagen. Dihydroxylysinonorleucine could be observed, if in a small amount, in the insoluble aorta collagen but not in both the soluble and insoluble skin collagens. Hydroxylysinonorleucine seemed to be present in only a small amount, although coeluting unknown substances made it difficult to evaluate correctly. Two unknown components decreasing with age were found; the one in the insoluble skin collagen and the other in the insoluble aorta collagen. Difference in reducible cross-link was indicated between the skin and aorta collagens.

Adolescent↗