Purification and N-terminal amino acid sequence of a chondroitin sulphate/dermatan sulphate proteoglycan isolated from intima/media preparations of human aorta

A proteoglycan (PG) was purified to homogeneity from intima/media preparations of human aorta specimens by the following chromatographic steps: Sepharose Q anion exchange, Sepharose CL-4B size exclusion, hydroxyapatite, MonoQ anion exchange and TSK G 4000 SW size exclusion. The purity of the preparation was established by SDS/PAGE using direct staining by silver or Dimethylmethylene Blue, as well as by Western blots of biotin-labelled samples. The electrophoretic mobility of the native PG was less than that of a 200,000-Mr standard protein. After treatment with chondroitin sulphate lyase ABC, a core protein of Mr 15,000 was revealed. The Mr of the glycosaminoglycan (GAG) peptides was less than 24,000, by comparison with a keratan sulphate peptide. The composition of the GAG chains was determined by differential digestion of the PG by chondroitin sulphate lyases AC/ABC or chondroitin sulphate lyase AC alone followed by anion-exchange chromatography of the resulting disaccharides. The GAG chains are composed of approximately one-third of dermatan sulphate and two-thirds chondroitin sulphate disaccharide units. The sequence of the 20 N-terminal amino acids is identical with the sequence previously reported for PG I isolated from human developing bone [Fisher, Termine & Young (1989) J. Biol. Chem. 264, 4571-4576]. The assignment of glycosylation sites to the serine residues in positions 5 and 10 was confirmed. The findings indicate that the chondroitin sulphate/dermatan sulphate PG is a major PG in intima/media preparations of human aorta and represents a biglycan-type PG.

Characterization of the endothelin binding site on bovine adrenomedullary chromaffin cells: comparison with vascular smooth muscle cells. Evidence for receptor heterogeneity

Specific binding sites for synthetic endothelin (ET) isoforms, ET-1 and ET-3 were studied in a bovine adrenomedullary chromaffin cell-rich preparation, and compared to those on A10 cells, a vascular smooth muscle cell line. Both [125I]ET-1 and [125I]ET-3 (2.5 x 10(-11) M) specifically bound to a single class of binding sites on the chromaffin cell preparation (apparent Kd 2.3 x 10(-10) and 1.4 x 10(-10) M, respectively), and the binding of both peptides was inhibited competitively by unlabeled ET-1, ET-3 and sarafotoxin S6b to an equal degree (IC50 values in the range 1.2 x 10(-10) to 3.1 x 10(-10) M). In contrast, only [125I]ET-1 (2.5 x 10(-11) M) specifically bound to A10 cells, to a single class of binding sites with apparent Kd of 1.5 x 10(-10) M. The same concentration of [125I]ET-3 displayed no evidence of specific binding. The binding of [125]ET-1 to A10 cells was inhibited competitively by unlabeled ET isoforms with the following order of potency: ET-1 (IC50, 3.1 x 10(-10) M) greater than Sarafotoxin S6b (IC50, 3.1 x 10(-9) M) greater than ET-3 (188 x 10(-9) M). ET-1 and ET-3 dose-dependently induced an increase in total inositol phosphate accumulation (the EC50 value of ET-1 was 1.3 x 10(-9) M). Neither ET-1 nor ET-3, up to 100 nM, affected the total inositol phosphate content of chromaffin cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Co-localization of immunoreactive forms of calponin with actin cytoskeleton in platelets, fibroblasts, and vascular smooth muscle

Calponin is an actin binding protein found in the smooth muscle cells of chicken gizzard. The localization of the protein was examined in bovine platelets, mouse fibroblasts, and the smooth muscle cells of the bovine aorta. Immunoblotting of whole platelet lysates revealed that the antibody to chicken gizzard calponin recognized two proteins with apparent molecular masses of 37 and 23 kDa in the resting state and an additional high-molecular-weight component (approximately 40 kDa) in the activated state. The localizations of calponin and caldesmon, and the correlation of their localizations with that of the actin cytoskeleton were analyzed by immunofluorescence microscopy using appropriate antibodies and rhodamine-phalloidin. In resting bovine platelets, calponin exhibited the same distribution as actin filaments, which are organized in a characteristic wheel-like structure. A similar distribution was observed with the anti-caldesmon antibody. Colocalization of calponin and actin were shown in activated platelets and along stress fibers of both fibroblasts and smooth muscle cells. These results suggest not only a cytoskeletal role associated with microfilaments but also a regulatory role of these proteins for actin-myosin interaction.

The cellular component in the parietal infiltrate of inflammatory abdominal aortic aneurysms (IAAA)

Eight cases of inflammatory abdominal aortic aneurysm (IAAA) (group I) and a control group of ten cases of atherosclerotic abdominal aortic aneurysm (AAA) with little or no parietal inflammatory infiltrate (group II) were studied; using light microscopy, transmission electron microscopy (TEM), and immunohistochemistry. These were used to define cell composition in the inflammatory process, the degree of cell activation and alteration of connective tissue. Large numbers of B lymphocytes were present in IAAA with preservation of the T4/T8 ratio. In addition, HLA-DR and the IL2-R antigen (specific for activated cells) were widely expressed in the cell population. The interstitial matrix contained deposits of IgG, IgM and C3c together with an increase in type III collagen and a reduction in elastin which appeared fragmented and swollen. This study, therefore, characterised the cellular component of the parietal inflammatory infiltrate in IAAA. The degree of activation shown by these cell elements and the activation of complement suggest that the relevant antigen may have been localised in the aneurysm wall at the time of observation.

Evaluation of the Ca2+ distribution in aortic tissue of spontaneously hypertensive and normotensive rats

In the present study, particle-induced X-ray emission (PIXE) was used to get information on the spatial distribution of Ca2+ in aortas of spontaneously hypertensive rats (SHR) and normotensive controls aged 1 week, 4 weeks, and 12 weeks. To differentiate changes in Ca2+ metabolism in hypertensive arteries from secondary phenomena due to the arteriosclerosis, the animals were examined in the earliest stage of hypertension. It was found that the Ca2+ content was not elevated in the aortic smooth muscle of SHR aged 1 week (n = 11), as compared to normotensive controls (n = 10) (186.8 +/- 89.9 micrograms Ca2+/g tissue v 254.0 +/- 173.3 micrograms Ca2+/g). The Ca2+ content was raised (P less than .05) in the aortic smooth muscle of SHR aged 4 weeks (n = 13), as compared to 12 WKY rats (4 weeks) (726.0 +/- 130.4 micrograms Ca2+/g tissue v 440.3 +/- 214.4 micrograms Ca2+/g) and in 17 SHR (3 months), as compared to 13 WKY rats, respectively (3390.1 +/- 729.9 micrograms Ca2+/g tissue v 1632.1 +/- 569.5 micrograms Ca2+/g). The results confirm the age-related increase in the arterial Ca2+ content in normotensive rats and demonstrate additionally that this age-related rise in arterial Ca2+ content is accelerated in SHR.

Localization of hyaluronan in various muscular tissues. A morphological study in the rat

The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analysed in various types of muscles in the rat by use of a hyaluronan-binding protein (HABP) and the avidin-biotin/peroxidase complex staining procedure. Microwave-aided fixation was used to retain the extracellular location of the glycosaminoglycan. In skeletal muscles, HYA was detected in the connective tissue sheath surrounding the muscles (epimysium), in the septa subdividing the muscle fibre bundles (perimysium) and in the connective tissue surrounding each muscle fibre (endomysium). HYA was heterogeneously distributed in all striated muscles. In skeletal muscles with small fibre dimensions (e.g., the lateral rectus muscle of the eye and the middle ear muscles), HYA was predominantly accumulated around the individual muscle fibres. Perivascular and perineural connective tissue formations were distinctly HYA-positive. In cardiac muscles, HYA was randomly distributed around the branching and interconnecting muscle fibres. In comparison, smooth muscle tissue was devoid of HYA.

Innervation of the human uterine artery and contractile responses to neuropeptides

The intrinsic innervation of the human uterine artery was investigated histochemically, and the motor responses to some of the demonstrated peptides and other humoral factors were studied on isolated vascular preparations. There were nerves with specific immunoreactivities for tyrosine hydroxylase, dopamine beta-hydroxylase, neuropeptide-Y (NPY), vasoactive intestinal peptide (VIP) and peptide histidine methionine, and enzymatic reactivity for acetylcholine esterase. The most effective stimulator of smooth muscle contractility was arginine vasopressin followed in order by oxytocin, noradrenaline together with NPY, noradrenaline alone and dopamine. No effect was seen with acetylcholine and tyrosine, and VIP caused inconsistent relaxation of contractile activity induced by PGF2 alpha. These results suggest that the uterine blood flow is regulated by complex interactions of factors, some occurring in nerve terminals and some being circulating humoral factors.

Modified low density lipoprotein isolated from atherosclerotic lesions does not cause lipid accumulation in aortic smooth muscle cells

Foam cells in atherosclerotic lesions are derived not only from blood monocytes but also from smooth muscle cells (SMC). To better understand the mechanisms by which SMC may become lipid-laden, we have studied the catabolism by cultured rabbit aortic SMC of LDL derived from atherosclerotic lesions (A-LDL) previously shown to be chemically modified. A-LDL was isolated either from homogenates of atherosclerotic plaques in human aortas by affinity chromatography and gel filtration, or from nonhomogenized extracts of plaque minces by ultracentrifugation and gel filtration. Internalization of A-LDL by SMC or fibroblasts appeared to be mediated primarily via the LDL receptor since: 1) either unlabeled LDL or A-LDL could inhibit the degradation of 125I-labeled A-LDL or of 125I-labeled LDL, 2) the uptake of both A-LDL and LDL, as estimated by their abilities to stimulate cholesterol esterification, was reduced in cells in which LDL receptor expression was down-regulated; and 3) the uptake of both [3H]cholesteryl ether-labeled A-LDL and LDL by normal fibroblasts was significant and could be inhibited by excess LDL, but was negligible in receptor-negative fibroblasts. At saturating concentrations of lipoproteins, maximum cholesterol esterification in SMC was greater for LDL than for A-LDL. Over a 48-h incubation, A-LDL, like LDL, was unable to induce cellular cholesteryl ester accumulation. Cross-competition studies suggested that either the affinity of A-LDL for the LDL receptor was less than that of LDL, or that some particles in A-LDL are not internalized by SMC. The latter alternative was supported by the observations that some A-LDL particles had undergone aggregation, especially at high concentrations, and that aggregated forms of A-LDL or plasma LDL failed to be internalized and degraded by SMC. Collectively, these results are consistent with recognition of some of the A-LDL particles by the LDL receptor, but also suggest that, at least under in vitro conditions, A-LDL is unlikely to induce lipid accumulation in SMC resulting in SMC-derived foam cells.

Evidence for distinct endothelin receptors in the pulmonary vascular bed in vivo

The present study was undertaken to investigate the effects of endothelin (ET) isopeptides on the pulmonary vascular bed of the intact, spontaneously breathing cat under conditions of constant pulmonary blood flow and left atrial pressure. When pulmonary vasomotor tone was actively increased by intralobar infusion of U46619, intralobar bolus injections of ET-1 (1 micrograms), ET-2 (1 micrograms), and ET-3 (3 micrograms) produced marked reductions in pulmonary and systemic vascular resistances. The pulmonary vasodilator response to each ET isopeptide was not altered by atropine (1 mg/kg i.v.), indomethacin (2.5 mg/kg i.v.), or ICI 118551 (1 mg/kg i.v.), but was significantly inhibited by an intra-arterial (i.a.) infusion of glybenclamide at 5 mg/kg. This dose of glybenclamide significantly inhibited the decrease in lobar arterial and systemic arterial pressures in response to intralobar injection of pinacidil (30 and 100 micrograms), whereas the pulmonary vasodilator responses to acetylcholine (0.03 and 0.1 micrograms) and prostaglandin I2 (0.1 and 0.3 micrograms) were not altered. The systemic vasodilator response to each ET isopeptide was not changed by glybenclamide or by the other blocking agents studied. The present data demonstrate for the first time that ET-1, ET-2, and ET-3 dilate the pulmonary vascular bed in vivo. The present data suggest that the pulmonary vasodilator response to ET isopeptides depends, in part, on activation of potassium channels and is mediated differently from the systemic vasodilator response to these substances. Contrary to earlier work, the present data indicate the pulmonary vascular response to ET isopeptides depends on the pre-existing level of pulmonary vasomotor tone. Furthermore, the present data suggest that in the lung ET-1, ET-2, and ET-3 may serve as endogenous agonists for potassium channels, a newly described vasodilator mechanism in the pulmonary vascular bed of intact adult animals.

Vascular smooth muscle biglycan represents a highly conserved proteoglycan within the arterial wall

Two overlapping cDNA clones containing sequences homologous to human bone biglycan were isolated from a rat vascular smooth muscle (VSM) cell cDNA library. Nucleotide sequence analysis demonstrated that these clones encoded the rat VSM biglycan complete core protein sequence. A high degree of genetic conservation was observed for biglycan since nucleotide sequence homology comparisons revealed an 88% homology occurring between rat and human biglycan cDNA coding regions. The deduced core protein for the secreted form of VSM biglycan was found to be composed of ten leucine-rich repeating units whose consensus sequence was similar to that present in human bone and bovine cartilage biglycans. Protein homology comparisons revealed that the mature rat VSM biglycan core protein was 97% homologous to both human bone and bovine cartilage biglycan core proteins. Most of the amino acid substitutions in the secreted form of rat VSM biglycan are of the conservative type thereby maintaining the hydrophobic property of this proteoglycan within the arterial wall. The highest frequency of amino acid substitutions occurring between rat, bovine and human biglycan core proteins was found to reside within a small hypervariable region located near the N-terminus of these proteoglycans. Rat VSM biglycan was found to contain dinucleotide repeat elements located in the 3' untranslated region of its mRNA which may influence the expression of this transcript. Biglycan mRNA levels were not found to vary significantly as a function of VSM cell density. However, biglycan transcript levels did vary significantly as a function of VSM cell growth state. Similar studies revealed that collagen, fibronectin, and laminin were able to influence biglycan mRNA levels in quiescent VSM cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Myosin isoform expression and smooth muscle cell heterogeneity in normal and atherosclerotic rabbit aorta

Two monoclonal antimyosin antibodies, Western blotting experiments, and immunofluorescence procedures were used to investigate myosin isoform expression in normal and atherosclerotic aortas of adult rabbits. The SM-E7 antibody reacted with the two myosin heavy chain (MHC) isoforms of smooth muscle (SM) type (SM-MHC-1 and SM-MHC-2) expressed in the adult rabbit aorta. The NM-G2 antibody recognized an epitope shared by the nonmuscle (NM) myosin heavy chains (NM-MHC) present in fibroblasts, macrophages, lymphocytes, and platelets. Two smooth muscle cell (SMC) populations were identified in the medial layer of normal adult aorta, namely cells that contained SM myosin exclusively and cells that showed the coexistence of SM and NM myosin isoforms. The size of the cell population with double myosin isoform content increased markedly during experimental atherogenesis and represented by far the predominant SMC phenotype in the atherosclerotic plaque. Western blotting analysis performed on crude extracts from the atherosclerotic plaque showed the presence of SM-MHC-1 and NM-MHC isoforms in this tissue. Co-expression of SM and NM myosin at the molecular and the cellular level were found in aortic tissue during the early stages of development. These results indicate that in experimental atherosclerosis, the accumulation in the plaque of SMC with an "immature" pattern of myosin isoform expression is accompanied by similar modifications in the differentiation pattern of SMC of the underlying media.

Changes in distribution of elastin and elastin receptor during intimal cushion formation in the ductus arteriosus

Changes in distribution of elastin and elastin receptor were studied during maturation of the ductus arteriosus. In this vessel intimal thickening is a normal process. It starts with separation of endothelial cells from the internal elastic lamina by the formation of a wide subendothelial region, followed by an increase in number of radially orientated cells in the inner media and subendothelial region. For the first time the nature of these originally inner media cells could be definitely determined as being derived from smooth muscle cells. Areas rich in these modified smooth muscle cells contained less elastin as compared with regions rich in circularly orientated smooth muscle cells. The internal elastic lamina had disappeared underneath intimal cushions of the canine ductus arteriosus, whereas in the fetal human ductus arteriosus, splitting of the internal elastic lamina was observed. Elastin was not present underneath separated endothelial cells, which suggests that these cells do not synthesize elastin, at least not after separation. Both smooth muscle cells and endothelial cells demonstrated the presence of the elastin receptor. Changes in its distribution were not observed. The temporal and spatial association between the altering distribution of elastin and the absence of normal cushion formation in the persistent ductus arteriosus suggests a role of the elastin receptor in the process of intimal thickening.

Human smooth muscle VLA-1 integrin: purification, substrate specificity, localization in aorta, and expression during development

A membrane glycoprotein complex was isolated and purified from human smooth muscle by detergent solubilization and affinity chromatography on collagen-Sepharose. The complex was identified as VLA-1 integrin and consisted of two subunits of 195 and 130 kD in SDS-PAGE. Liposomes containing the VLA-1 integrin adhered to surfaces coated with type I, II, III, and IV collagens, Clq subcomponent of the first component of the complement, and laminin. The liposomes specifically adhered to these proteins in a Ca2+, Mg2(+)-dependent manner, but did not bind to gelatin, fibronectin, and thrombospondin substrates. The expression of VLA-1 integrin in different human tissues and cell types, and during aorta smooth muscle development was studied by SDS-PAGE, and subsequent quantitative immunoblotting was performed with antibodies recognizing alpha 1 and beta 1 subunits of the VLA-1 integrin. A high level of VLA-1 integrin expression was an exceptional feature of smooth muscles. Fibroblasts, endothelial cells, keratinocytes, striated muscles, and platelets contained trace amounts of VLA-1 integrin. In the 10-wk-old human fetal aorta, VLA-1 integrin was found only in smooth muscle cells whereas mesenchymal cells, surrounding aortic smooth muscle cells, were VLA-1 integrin negative. By the 24th wk of gestation, the amount of VLA-1 integrin was significantly reduced in the aortic media (4.3-fold for alpha 1 subunit and 2.5-fold for beta 1 subunit) compared with that in the 10-wk-old aortic smooth muscle cells. After birth, the expression of VLA-1 integrin increased and in the 1.5-yr-old child aorta the VLA-1 integrin level was almost the same as in adult aortic media. Smooth muscle cells from intimal thickening of adult aorta express five times less alpha 1 subunit of VLA integrin that smooth muscle cells from adult aortic media. In primary culture of aortic smooth muscle cells, the content of the VLA-1 integrin was dramatically reduced and subcultured cells did not contain VLA-1 integrin at all.

Alpha 1-adrenergic receptors in pulmonary and systemic vascular smooth muscle. Alterations with development and pregnancy

alpha 1-Adrenergic receptors mediate vasoconstriction in the pulmonary and systemic vasculature. In sheep the in vivo vasoconstrictor response to alpha 1-adrenergic stimulation is less in the pulmonary circulation compared with the systemic circulation of the fetus, the response increases in both vascular beds with fetal and postnatal development, and it decreases in the systemic vasculature with pregnancy. In an effort to determine the mechanisms underlying these differences, alpha 1-adrenergic receptor binding characteristics were determined by using [3H]prazosin in intrapulmonary and systemic (thoracic aorta) vascular smooth muscle (VSM) from late-gestation fetal lambs and from pregnant and nonpregnant ewes. alpha 1-Adrenergic receptor density was less in fetal intrapulmonary VSM that in fetal aortic VSM (12.4 +/- 1.5 versus 29.4 +/- 3.2 fmol/mg protein, p less than 0.05), and it was less (p less than 0.05) in the fetus compared with the pregnant ewe in both intrapulmonary and aortic VSM (51.0 +/- 5.2 and 76.5 +/- 5.9 fmol/mg protein, respectively). alpha 1-Adrenergic receptor density in intrapulmonary VSM was similar in the pregnant and nonpregnant ewe (61.9 +/- 7.2 fmol/mg protein), whereas in aortic VSM it was less (p less than 0.05) in pregnant ewes compared with nonpregnant ewes (101.0 +/- 5.5 fmol/mg protein). alpha 1-Adrenergic receptor affinity was similar in all the VSM sources tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and characterization of an unique kidney antigen of relevance in human renal disease

Recently we described a monoclonal antibody, designated 7-5Q, with specificity for a human non-glomerular basement membrane capillary wall antigen. In order to purify and characterize the corresponding antigen for the development of sensitive ELISA techniques, applicable to the diagnosis and monitoring of renal disease, human kidney cortices were extracted with a variety of detergents. A double band of 98/105 kD was evident by immunoblotting in all preparations most notably with a Triton X-114 extract. The caprylic acid- and ammonium sulfate-purified monoclonal antibody 7-5Q was covalently bound to CNBr-activated Sepharose and detergent extracts were applied to this affinity material. A pure protein of 98/105 kD (double band on SDS-polyacrylamide gels) was eluted. Glycan typing with lectins revealed N-acetyl glucosamine-residues and amino acid analysis a relatively high content of acidic (31%) and hydrophobic (30%) amino acids, indicating that the antigen is an acidic, membrane-bound glycoprotein.

The amyloid beta-protein precursor is localized in smooth muscle cells of leptomeningeal vessels

We examined leptomeningeal vessels using 2 different antisera which recognized both terminal ends of amyloid beta-protein precursor (APP). Both antisera recognized a 120-kDa protein from leptomeningeal vessels. Immunocytochemistry showed that APP was localized in the smooth muscle cells of leptomeningeal vessels. These results indicated that the smooth muscle cells of leptomeningeal vessels contained full-length native APP, and that the cerebrovascular amyloid in the leptomeningeal vessels was derived from this APP.

The smooth muscle 132 kDa cyclic GMP-dependent protein kinase substrate is not myosin light chain kinase or caldesmon

Atrial natriuretic peptide (ANP) stimulates the phosphorylation of three cyclic GMP-dependent protein kinase substrate proteins of 225, 132, and 11 kDa (P225, P132 and P11 respectively) in the particulate fraction of cultured rat aortic smooth muscle cells [Sarcevic, Brookes, Martin, Kemp & Robinson (1989) J. Biol. Chem. 264, 20648-20654]. Vrolix, Raeymaekers, Wuytack, Hofmann & Casteels [(1988) Biochem. J. 255, 855-863] have reported the presence of a 130 kDa cyclic GMP-dependent protein kinase substrate protein in the membrane fraction of pig aorta or stomach, and suggested that it may be myosin light chain kinase (MLCK). The aim of the present study was to determine whether P132 from rat aorta was MLCK or caldesmon. Although P132 co-migrates with purified chicken gizzard MLCK on SDS/polyacrylamide gels, it is distinct from rat aortic MLCK. Partially purified MLCK from rat aorta migrated as a 145 kDa protein on SDS/polyacrylamide gels. Immunoblotting the partially purified rat aortic MLCK with antibody to bovine tracheal MLCK identified rat aortic MLCK (145 kDa) and a corresponding 145 kDa protein in the particulate fraction of cultured rat aortic smooth muscle cells, but did not detect the 132 kDa protein. Phosphopeptide maps of purified rat aortic MLCK prepared by digestion with Staphylococcus aureus V8 protease were distinct from those of P132. P132 was not caldesmon, since antibodies to caldesmon cross-reacted with 136 and 76 kDa proteins in the particulate fraction of rat aortic cells, but not with P132. Furthermore, caldesmon was partially extracted from the particulate into the soluble fraction by heating at 90 degrees C, whereas P132 was not. These results demonstrate that the ANP-responsive cyclic GMP-dependent protein kinase substrate of 132 kDa from rat aortic smooth muscle cells is not MLCK or caldesmon.

Potential diagnostic value of the umbilical artery as a definition of neural fatty acid status of the fetus during its growth: the umbilical artery as a diagnostic tool

Summary

Low birth weight (LBW) is associated with handicaps, the most prevelant of which affect the brain or its sensory attributes and have a life long impact. We have therefore been interested in nutrition and fetal growth and have studied the relationship between maternal diet and the outcome of pregnancy.

Essential fatty acids are methylene-interrupted, polyenoic fatty acids that are required for cell membrane structure, integrity and function. Some 60% of the structural material of the brain and nervous system is lipid and it uses 20- and 22-carbon-chain-length polyenoic acids specifically in sites of signal transduction and high activity (Fig. 1).

We have been interested in the acquisition of these fatty acids during fetal growth and along with deficits of several nutrients found low intakes of essential fatty acids (EFA) in the mothers of LBW babies. In order to test this food intake data we have analysed the lipids of the umbilical artery as representative of fetal tissue.

We found surprisingly high proportions of the n − 9 eicosatrienoic acid (20:3, n − 9) and docosatrienoic acid (22:3, n − 9). The 20:3, n − 9 is known as the Mead acid and is recognized as a biochemical index of EFA deficiency [1,2]. The 20:3, n − 9/2:4, n − 6 ratio has been used as a biochemical test of general EFA deficiency and the 22:5, n − 6/ 22:4, n − 6 ratio as a marker of docosahexaenoic or n − 3 deficiency. Both ratios were unusually high. Further analysis of 14 babies of different birth weights produced highly significant Pearson correlation coefficients between birth weights and head circumferences, and these two indices, which were negative, and greater in the ethanolamine phosphoglycerides than in the choline phosphoglycerides of the umbilical artery.

The ethanolamine phosphoglycerides are inner membrane lipids and therefore the presence of the Mead acid and high levels of 22:5, n − 6 are statements about the biochemical history of the individual fetus. These indices may therefore have a diagnostic value as a measure of the nutritional status of the fetus during its growth. Because they describe the status of fatty acids specifically used for neural tissue growth, this diagnostic tool has a potential, which needs now to be tested, for assessing risk of neural deficits or damage in, for example, LBW and premature infants.

Differential effects of carbachol on cytosolic calcium levels in vascular endothelium and smooth muscle

Effects of norepinephrine (NE), carbachol (CCh) and histamine (HIS) on vascular tone and the endothelial and smooth muscle cytosolic C++ levels ([Ca++]i) were examined in rat aorta. The fura-2-Ca++ fluorescence emitted from endothelial and smooth muscle cells was detected at the endothelial surface. In the aorta with endothelium, NE increased both [Ca++]i and muscle tension whereas CCh slightly relaxed the muscle and increased [Ca++]i. The CCh-stimulated [Ca++]i was partially inhibited by verapamil. Addition of CCh to the NE-stimulated aorta relaxed the muscle with additional increase in [Ca++]i and positive correlation was obtained between the increase in [Ca++]i and relaxation. In the aorta without endothelium, NE increased both [Ca++]i and tension although CCh was ineffective. When endothelium was removed only from a small area from where the fura-2-Ca++ fluorescence was detected, CCh relaxed the muscle without changing [Ca++]i. In this preparation, NE increased both [Ca++]i and muscle tension and sequential addition of CCh relaxed the muscle with a small decrease in [Ca++]i, suggesting that Ca++ sensitivity of contractile elements is decreased. In Ca+(+)-free solution, CCh induced a transient increase in [Ca++]i and a decrease in muscle tension only in the presence of endothelium. HIS showed similar effects as CCh. By contrast, sodium nitroprusside decreased [Ca++]i and relaxed the muscle in NE-stimulated aorta with or without endothelium. These results suggest that CCh and HIS increase [Ca++]i in the endothelial cells which regulates the synthesis and/or release of endothelium-derived relaxing factor. Endothelium-derived relaxing factor may decrease [Ca++]i in the smooth muscle cells and also decrease Ca++ sensitivity of contractile elements resulting in vasodilatation.

Receptors for atrial natriuretic factor in cardiomyocytes and aortic smooth muscle

The aim of this work was to investigate whether specific receptors for atrial natriuretic factor (ANF) are present in ventricular cardiomyocytes and aortic smooth muscle membranes. 125I-ANF was employed to test the binding of the radioligand to isolated rat cardiomyocytes. Calcium-tolerant ventricular cardiomyocytes were obtained by retrograde perfusion with collagenase. 125I-ANF binding to cardiomyocytes was highly specific (70-80%) with a KD value of 72.6 pM and a Bmax of 9.37 fmol/mg protein. In other studies, 125I-ANF binding was investigated with a membrane preparation obtained from calf thoracic aorta, from which the endothelium had been previously stripped off. In this preparation too the interaction of 125I-ANF (70-80%) was highly specific, with a KD value of 70.4 pM and a Bmax of 8.78 fmol/mg protein. These results suggest that specific receptors to atrial natriuretic factor are present both in isolated rat cardiomyocytes and in the smooth muscle of calf thoracic aorta. This second observation is in agreement with the hypothesis that the vasodilator effect of atrial natriuretic factor is due to a direct interaction between this peptide and vascular smooth muscle cells.

High-affinity binding sites for [3H]saxitoxin are associated with voltage-dependent sodium channels in portal vein smooth muscle

Saturable, high-affinity binding sites for [3H]saxitoxin were identified in equine portal vein smooth muscle membranes. These sites had a dissociation constant of 0.29 nM and a maximal binding capacity of 115 fmol.mg-1 of protein. A similar dissociation constant was obtained with cells prepared from rat portal vein. Specific binding of [3H]saxitoxin was completely displaced by unlabelled saxitoxin and tetrodotoxin, with inhibition constants of 0.42 and 2.10 nM, respectively. Tetrodotoxin blocked the fast Na+ current in single cells of rat portal vein in a concentration-dependent manner, with an IC50 of 3.15 nM. These results suggest that the high-affinity binding sites for tetrodotoxin and saxitoxin may be associated with voltage-dependent Na+ channels in vascular myocytes.

[Desialylated low density lipoproteins--atherogenic lipoproteins occurring in blood of patients with coronary atherosclerosis]

We have recently established that LDL of most patients with coronary atherosclerosis differ from the LDL of most healthy subjects by the ability to cause primary atherosclerotic changes, i.e. the accumulation of intracellular cholesterol in the cells of smooth muscle origin cultured from unaffected intima of human aorta. We assumed that patients LDL is modified lipoprotein differing from native LDL by chemical composition. It has been established in the present study that patients LDL has a substantially lower content of sialic acid as compared with the LDL of healthy subjects. Desialylation of native LDL of healthy subjects with neuraminidase makes them atherogenic, therefore, capable of causing the accumulation of intracellular cholesterol similarly to patients LDL.

Competence growth factors evoke the phenotypic transition of arterial smooth muscle cells

Vascular smooth muscle cells (V-SMC) alter their functions from contraction to production of extracellular matrices during the response to injury of the arterial wall. Accumulation of these matrices characterize the chronic structural change of arteriosclerosis. In this paper, we reported as follows. (1) V-SMC freshly isolated from human aortic media had strong reactivity with anti-smooth muscle specific alpha-actin (alpha-SM actin) antibody but not with anti-prolyl 4-hydroxylase (ProHy) antibody. (2) The exponentially growing cells in serum-containing culture media reduced alpha-SM actin and induced ProHy distinctly. (3) Growth-arrested cells with serum starvation rearranged numerous alpha-SM actin fibers in their cytoplasm. And the rearrangement of contractile filaments inhibited by the addition of single competence growth factor, such as platelet derived growth factor (PDGF) or basic fibroblast growth factor (bFGF). These results suggest that V-SMC change their phenotype in a competence-factor-dependent manner.

[Distribution of myosin, desmin and vimentin in smooth muscle cells of human embryonic vessels]

Immunofluorescent study of embryonal vessels of man using antibodies to myosin, desmin and vimentin showed heterogeneity of smooth muscle cells. It is supposed that the use of desmin as a marker of cell differentiation can increase the role of modified phenotypes in the development of the pathological process in the vascular wall.

Ca2+ analysis in arteries of spontaneously hypertensive rats by proton-induced X-ray emission

Numerous investigations have shown that Ca2+ plays an important role in the pathogenesis of hypertension. Intracellular Ca2+ measurements have been carried out with Ca(2+)-selective electrodes and the Quin 2 method. The present study used particle induced X-ray emission to investigate the Ca2+ distribution in arterial smooth muscle. This method correlates Ca2+ distribution with the morphological structure of the tissue. The Ca2+ content of the aortas and renal arteries was measured in 22 spontaneously hypertensive and 11 normotensive rats. The findings demonstrate significant Ca(2+)-elevation in the aortas of spontaneously hypertensive rats compared with the aortas of normotensive rats (3124.9 +/- 790.0 versus 2031 +/- 478 micrograms Ca2+/g; P < 0.05), whereas there was only a tendency to Ca2+ elevation in the renal arteries of spontaneously hypertensive rats compared with normotensive rats (3336.0 +/- 1798.0 versus 1533.2 +/- 1082.0 micrograms Ca2+/g; NS). The Ca2+ was mainly detected in the muscle containing tunica media.