RESUMO
Beta-hydroxy-beta-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors reduce plasma LDL cholesterol by upregulating hepatic LDL receptors. However, their effects on lipid metabolism in extrahepatic cells may also contribute to their therapeutic benefit. We examined the effects of lovastatin (LOV) on cellular lipid levels in the human monocytic Mono Mac 6sr and cultured rat smooth muscle cells. In both cell types, LOV produced a dose-dependent increase in cellular triglycerides. This increase was observed in cells grown in the absence of exogenous lipids in the culture medium, but was more pronounced after additions of oleic acid (50 to 200 microM) and VLDL (50 to 200 microg ml-1). In Mono Mac 6sr cells grown in medium containing 10% delipidated FCS for the last 16 h, the LOV-induced rise in triglyceride levels was completely reversed by 2 mM mevalonic acid and was associated with a decrease in cellular cholesterol. However, when cells were maintained in lipoprotein-replete medium, the LOV-induced rise in triglycerides did not correlate with cellular cholesterol. LOV also reduced cellular cholesterol esterification and increased the synthesis of fatty acids and their incorporation into triglycerides and phospholipids. Increased triglyceride levels were also seen in Mono Mac 6sr cells treated with the lanosterol demethylase inhibitor RS-21607 and the acylcoenzyme A:cholesterol acyltransferase inhibitor SaH 58035. Our findings suggest that the LOV-induced triglyceride accumulation involves changes in intracellular cholesterol pools regulating cellular fatty acid concentrations. Although decreased cholesterol levels in cells participating in plaque formation are beneficial, the impact of the herein described shift in intracellular neutral lipid metabolism on other cellular functions warrants further investigation.
Assuntos
Amidas/farmacologia , Lovastatina/farmacologia , Monócitos/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Compostos de Organossilício/farmacologia , Triglicerídeos/metabolismo , Acetatos/metabolismo , Compostos de Anilina/farmacologia , Animais , Anticolesterolemiantes/farmacologia , Linhagem Celular , Colesterol/metabolismo , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Metabolismo dos Lipídeos , Lipoproteínas LDL/metabolismo , Lipoproteínas LDL/farmacologia , Lipoproteínas VLDL/metabolismo , Lipoproteínas VLDL/farmacologia , Ácido Mevalônico/farmacologia , Monócitos/metabolismo , Músculo Liso/metabolismo , Ácido Oleico/metabolismo , Ratos , Ratos Wistar , Sulfetos/farmacologiaRESUMO
Superoxide anions (O2-) are supposedly involved in the pathogenesis of endothelial dysfunction. We investigated whether the enhanced formation of O2- is involved in the attenuation of endothelium-dependent relaxation induced by lipopolysaccharide (LPS). Rats were injected with LPS (10 mg/kg IP), the aorta was removed after 12 or 30 hours, and generation of O2-, H2O2, and ONOO- was measured using chemiluminescence assays. Protein tyrosine nitration and expression of xanthine oxidase (XO), NAD(P)H oxidase, and manganese superoxide dismutase were determined by Western or Northern blotting, and endothelium-dependent relaxation in aortic rings was studied. LPS treatment increased vascular O2- (from 35+/-2 cpm/ring at baseline to 166+/-21 cpm/ring at 12 hours and 225+/-16 cpm/ring at 30 hours) and H2O2 formation, which was partially sensitive to the NAD(P)H oxidase inhibitor diphenylene iodonium at both time points studied and to the XO inhibitor oxypurinol only 30 hours after LPS treatment. Expression of XO and NAD(P)H oxidase (p22phox, p67phox, and gp91phox) were increased by LPS in a time-dependent manner, as were protein tyrosine nitration and ONOO- formation. LPS also induced expression of the oxidative stress-sensitive protein manganese superoxide dismutase. Endothelium-dependent relaxation was impaired after LPS treatment and could not be restored by inhibition of inducible NO synthase. Inhibition of O2- with superoxide dismutase, oxypurinol, tiron, or the superoxide dismutase mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride did not restore but further deteriorated the relaxation of LPS-treated rings. In summary, treatment of rats with LPS enhances vascular expression of XO and NAD(P)H oxidase and increases formation of O2- and ONOO-. Because removal of O2- compromised rather than restored endothelium-dependent relaxation, a direct role of O2- in the induction of endothelial dysfunction is unlikely. Other mechanisms, such as prolonged protein tyrosine nitration by peroxynitrite (which is formed from NO and O2-) or downregulation of the NO effector pathway, are more likely to be involved.
Assuntos
Endotélio Vascular/fisiopatologia , Endotoxemia/fisiopatologia , Infecções por Escherichia coli/fisiopatologia , NADPH Oxidases/fisiologia , Superóxidos/metabolismo , Xantina Oxidase/fisiologia , Análise de Variância , Animais , Aorta/metabolismo , Aorta/fisiologia , Northern Blotting , Regulação para Baixo , Inibidores Enzimáticos/farmacologia , Escherichia coli , Immunoblotting , Técnicas In Vitro , Lipopolissacarídeos/administração & dosagem , Medições Luminescentes , Relaxamento Muscular , Músculo Liso Vascular/fisiologia , NADPH Oxidases/antagonistas & inibidores , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Oniocompostos/farmacologia , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/fisiologiaRESUMO
Besides its dose-dependent alpha- and beta-adrenoceptor-mediated vascular action, hormonal effects of epinephrine also involve the activation of renin secretion by direct stimulation of renal beta 1-adrenoceptors. To determine the interrelation between increased plasma renin activity in response to epinephrine and plasma aldosterone concentration and renal excretion of potassium and sodium, 26 normal subjects were subjected to 4 h of an intravenous infusion of low-dose epinephrine (12 ng/kg/min). Epinephrine infusion raised mean plasma epinephrine concentration 2.8-fold above control (P < .001). Plasma renin activity (PRA) increased by 56% (P < .01) during epinephrine infusion, whereas plasma aldosterone concentration remained constant. Infusion of epinephrine also resulted in markedly suppressed urinary potassium excretion (-32%; P < .025), while urinary sodium excretion was not altered. Serum potassium was decreased by 4.1% during epinephrine (P < .025). Systolic blood pressure and heart rate did not change, and diastolic blood pressure was slightly reduced by 5 mm Hg (P < .025). In summary, during low-dose epinephrine infusion PRA is markedly increased while plasma aldosterone remains unchanged. The fall in urinary potassium excretion in the presence of reduced serum potassium concentration is most likely mediated via the beta-adrenoceptor-mediated shift of potassium into cells. This in turn may prevent a concomitant rise of plasma aldosterone, which subsequently contributes to the blunted kaliuresis and unchanged natriuresis found during the epinephrine-induced rise of PRA. In conclusion, the epinephrine-induced fall in serum potassium appears to be the predominant regulator of plasma aldosterone concentration even in the presence of a stimulated PRA.
Assuntos
Aldosterona/sangue , Epinefrina/farmacologia , Sistema Renina-Angiotensina/efeitos dos fármacos , Renina/sangue , Adulto , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Relação Dose-Resposta a Droga , Epinefrina/administração & dosagem , Humanos , Infusões Intravenosas , Masculino , Potássio/urina , Sistema Renina-Angiotensina/fisiologia , Sódio/urinaRESUMO
Elevated plasma epinephrine concentrations may impair blood pressure homeostasis and renal sodium and volume excretion in response to central hypervolemia. We studied the effects of a low-dose epinephrine infusion (12 ng/kg/min) on cardiovascular and renal responses to a thermoneutral head-out water immersion in eleven healthy men. Responses to water immersion without epinephrine were characterized by significant suppression of plasma renin activity (PRA), plasma aldosterone concentration, and renal norepinephrine excretion, and an augmentation of natriuresis and diuresis. Epinephrine infusion, which raised mean plasma epinephrine concentration 4.3-fold, slightly increased plasma norepinephrine and renal norepinephrine excretion, markedly stimulated PRA (+66.7%), but decreased plasma aldosterone (-11.7%), and augmented renal sodium and volume excretion. Despite the presence of the epinephrine infusion, water immersion continued both to suppress PRA and aldosterone, and to increase natriuresis and diuresis in a qualitatively similar pattern. During all conditions blood pressure and heart rate remained unchanged. It is concluded that physiologic responses to central hypervolemia are not impaired at stress levels of circulating epinephrine. During epinephrine infusion, despite a concomitant increase in plasma norepinephrine and a stimulation of PRA, blood pressure remained constant in response to water immersion due to an augmentation of natriuresis and diuresis.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Epinefrina/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Imersão/fisiopatologia , Rim/fisiologia , Adulto , Aldosterona/sangue , Cloretos/metabolismo , Creatinina/metabolismo , Epinefrina/administração & dosagem , Epinefrina/metabolismo , Hematócrito , Humanos , Rim/efeitos dos fármacos , Masculino , Norepinefrina/metabolismo , Concentração Osmolar , Potássio/sangue , Renina/sangue , Sódio/sangueRESUMO
Endothelin-1 is a vasoactive peptide produced by endothelial cells. Endothelin-1 exerts potent vasoconstrictory effects upon vascular smooth muscle cells, and it may play a role in the pathogenesis of several cardiovascular disorders such as atherosclerosis and ischemic conditions. Besides the investigation of its biological effects, knowledge about cellular mechanisms of the synthesis, signal transduction pathway(s) and receptor-mediated actions on target cells is mandatory for the development of pharmacological strategies in the treatment of cardiovascular disease. In this review cellular mechanisms of endothelial endothelin-1 synthesis and release are discussed.
Assuntos
Doenças Cardiovasculares/fisiopatologia , Endotelina-1/biossíntese , Endotélio Vascular/fisiopatologia , Humanos , Músculo Liso Vascular/fisiopatologia , Receptores de Endotelina/fisiologia , Transdução de Sinais/fisiologia , Vasoconstrição/fisiologiaRESUMO
The endothelins are a family of potent vasoconstrictors and mitogenic agents. Since the isolation of ET-1 in 1988 the worldwide scientific research interest has mushroomed, resulting in considerable knowledge about molecular biology, biochemistry and pharmacological actions of these peptides. A body of evidence has parallelly emerged pointing to their role in some physiological phenomena as well as in the pathophysiology of cardiovascular disease. The future therapeutic use of anti-endothelin strategies may offer clinical benefit in many of these conditions.
Assuntos
Doenças Cardiovasculares/fisiopatologia , Endotelina-1/fisiologia , Vasoconstrição/fisiologia , Endotélio Vascular/fisiopatologia , Hemodinâmica/fisiologia , Humanos , Músculo Liso Vascular/fisiopatologia , Receptores de Endotelina/fisiologiaRESUMO
The endothelium-derived 21 amino acid peptide endothelin-1 is one of the most potent vasoconstrictors. Endothelin-1 exerts its effects upon a variety of vascular and non-vascular cells through a direct interaction with specific receptors. Beyond its vasoconstrictive action on vascular smooth muscle cells endothelin-1 has mitogenic and pro-inflammatory properties. The present review deals with current experimental and clinical evidence for the involvement of endothelin-1 in several cardiovascular disorders with inflammatory components. We further discuss the potential clinical relevance of the endothelin system and therapeutical perspectives of anti-endothelin strategies in the treatment of cardiovascular disease.
Assuntos
Doenças Cardiovasculares/fisiopatologia , Endotelina-1/fisiologia , Endotélio Vascular/fisiopatologia , Vasoconstrição/fisiologia , Humanos , Músculo Liso Vascular/fisiopatologia , Doença de Raynaud/fisiopatologiaRESUMO
The report describes a previously healthy 24-year-old women presenting with acute abdominal pain following a hyperextension manoeuvre. The key finding of a continuous bruit with systolic and diastolic components in the epigastric region subsequently led to the diagnosis of an intramural haematoma of the coeliac artery, that caused a subtotal occlusion of the artery. The diagnosis was achieved by both colour-coded duplex sonography and magnetic resonance angiography. The case shows that a conservative management rather than operative reconstruction is justified in an oligo-symptomatic situation with no signs of end-organ damage as in this patient.
Assuntos
Arteriopatias Oclusivas/diagnóstico , Artéria Celíaca , Hematoma/diagnóstico , Angiografia por Ressonância Magnética , Músculo Liso Vascular , Ultrassonografia Doppler em Cores , Doença Aguda , Adulto , Artéria Celíaca/lesões , Artéria Celíaca/patologia , Diagnóstico Diferencial , Feminino , Humanos , Músculo Liso Vascular/patologia , Ferimentos não Penetrantes/diagnósticoRESUMO
The interaction of two tranquilizers, the 1,5-benzodiazepine clobazam (CBZ, Frisium) and the non-benzodiazepine etifoxin (Hoe-36,801) hydrochloride (EFX, 6-chloro-2-ethylamino-4-methyl-4-phenyl-4H-3,1-benzoxazine HCl) was investigated for anticonvulsant activity in mice. Corresponding experiments were performed with the antiepileptic drug sodium valproate (VPA). Tonic-clonic (maximal) seizures were induced by maximal electroshock (MES; 12 mA, 200 ms) and clonic (threshold) seizures by pentetrazol (PTZ; 85 mg/kg s.c.). The addition of an anticonvulsant threshold dose of EFX (50 mg/kg p.o.) led to an increase of CBZ's potency against both MES- and PTZ-seizures by 410 or 450%, respectively. Under the same conditions, EFX enhanced the potency of VPA only by 20 or 80% and a threshold dose of VPA (100 mg/kg p.o.) enhanced the potency of CBZ by 110 or 0%, respectively. It is concluded that this potentiation of CBZ's anticonvulsant activity by EFX may be beneficially used in epileptic patients either to increase CBZ's antiepileptic effects or to reduce CBZ's therapeutic doses in order to prevent or delay the development of resistance.
Assuntos
Ansiolíticos , Anticonvulsivantes , Benzodiazepinas , Benzodiazepinonas/farmacologia , Oxazinas/farmacologia , Animais , Clobazam , Sinergismo Farmacológico , Masculino , Camundongos , Convulsões/prevenção & controle , Ácido Valproico/farmacologiaRESUMO
The anticonvulsant potential of 6-chloro-2-(ethylamino)-4-methyl-4-phenyl-4H-3,1-benzoxazine (etifoxine), a non-benzodiazepine tranquilizer, was evaluated in mice in comparison to valproate, phenytoin and clobazam. Maximal seizures were induced by electroshock (MES) and the chemical convulsants pentetrazol (PTZ), picrotoxin (PTX), bicuculline (BIC), isoniazid (INH), nicotine (NIC) and strychnine (STR). Tonic extensor convulsions were prevented by etifoxine in the following rank order of potency (ED50 values with seizure tests): 39.5 (PTX), 101 (PTZ), 101 (MES), 154 (INH), 181 (NIC), 397 (BIC), and greater than 800 mg/kg p.o. (STR). Clonic seizures were induced by threshold doses of PTZ, PTX and pilocarpine (PIL) and antagonized by etifoxine at ED50 values of 181 (PIL), 221 (PTZ), and greater than 800 mg/kg p.o. (PTX). Hence, etifoxine blocked both tonic and clonic seizures but was more potent against the tonic component. The anticonvulsant profile of etifoxine appeared similar to that of valproate. However, in terms of potency, protective indices (ED50 rotarod/ED50 seizure test) and therapeutic indices (LD50/ED50 seizure test) etifoxine was on an average 3.7, 12 and 14 times superior to valproate, respectively. It is concluded that etifoxine has a marked anticonvulsive potential and may be beneficially used in epileptic disorders, especially of the grand mal type.
Assuntos
Anticonvulsivantes/farmacologia , Benzodiazepinas , Benzodiazepinonas/farmacologia , Oxazinas/farmacologia , Fenitoína/farmacologia , Ácido Valproico/farmacologia , Animais , Ansiolíticos/farmacologia , Anticonvulsivantes/toxicidade , Benzodiazepinonas/toxicidade , Clobazam , Eletrochoque , Dose Letal Mediana , Masculino , Camundongos , Oxazinas/toxicidade , Fenitoína/toxicidade , Equilíbrio Postural/efeitos dos fármacos , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Ácido Valproico/toxicidadeRESUMO
The part played by cardiotocographically recordable foetal movements was studied. The totality of all cardiotocographically, that is objectively, foetal movements together with all movements perceived, subjectively, by the pregnant women concerned was used as reference value. - A HP-2100S computer was used in on-line evaluation. Those foetal movements perceived by the women concerned were fed into the computer by keyboard input. - Two thirds of all foetal movements were recorded both ways, at one and the same time. A total of 9.1 per cent was not confirmed by the probands, while 27.4 per cent were perceived only by the probands. A total of 72.6 per cent of all foetal movements was recorded by the cardiotocograph, while 80.9 per cent were perceived by the women involved. - Hence, there should be no clinical objection to non-stress testing, but the above data should be taken into account. - As soon as subjectively perceived foetal movements can be objectively marked, the question should be asked for possible superiority of such human perception over tocometry.
Assuntos
Computadores , Monitorização Fetal/instrumentação , Feminino , Frequência Cardíaca , Humanos , Movimento , Gravidez , Terceiro Trimestre da GravidezRESUMO
In ANCA-associated vasculitis the activation of primed leucocytes by autoantibodies with subsequent release of proteases such as myeloperoxidase (MPO), proteinase 3 (PR3) and elastase is thought to play an important pathogenetic role. Whether these proteases contribute to the vascular lesions by stimulating the procoagulant activity of these cells is unknown. Tissue factor (TF) expression and activity were investigated in human umbilical vein endothelial cells after stimulation with MPO, PR3 and elastase. TF activity was measured using a one-stage clotting assay. Polyclonal antibodies to TF were used to prove specificity. TF mRNA was detected by reverse transcriptase-polymerase chain reaction. PR3 and elastase led to a significant increase in TF mRNA expression and increased activity. The stimulation was not mediated by IL-1. The stimulatory effect of PR3 did not depend on its proteolytic activity (no inhibition by alpha-1-antitrypsin), whereas the effect of elastase was blocked by alpha-1-antitrypsin. MPO had no effect on TF activity. These results show that PR3 and elastase stimulate TF expression in human endothelial cells. In ANCA-associated vasculitis the increased release of proteases may contribute to the development of microthrombi and consecutive necrosis.
Assuntos
Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Elastase Pancreática/farmacologia , Serina Endopeptidases/farmacologia , Tromboplastina/metabolismo , Anticorpos Anticitoplasma de Neutrófilos/metabolismo , Células Cultivadas , Expressão Gênica/efeitos dos fármacos , Humanos , Proteína Antagonista do Receptor de Interleucina 1 , Interleucina-1/metabolismo , Mieloblastina , Elastase Pancreática/metabolismo , Peroxidase/metabolismo , Peroxidase/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Serina Endopeptidases/metabolismo , Sialoglicoproteínas/farmacologia , Tromboplastina/genética , Vasculite/etiologia , Vasculite/imunologia , Vasculite/metabolismoRESUMO
With 529 patients (4 groups) abortion was induced through intermittend extraamniotic application of PGF2alpha. In 97,9 per cent, the hourly instillation of PGF2alpha led to the desired success: 25 (4,7 per cent) complete abortions, 416 (78,6 per cent) incomplete abortions, 77 (14,6 per cent) "missed" abortions with opening of the cervix. In groups I to III (primigravidae betw-en the 6th and 12th weeks of pregnancy), in the mean PGF2alpha dosages there were no significant differences between 6,84 and 6,27 mg. The mean abortion time was between 8 hr 32 min and 7 hr 43 min. In group IV ("problem cases" in the first and second trimester of pregnancy), the mean PGF2alpha dosage was 10,68 mg. The mean abortion time 12 hr 04 min. The total complication rate was at 2,2 per cent.
Assuntos
Aborto Induzido/métodos , Prostaglandinas F/administração & dosagem , Útero , Adolescente , Adulto , Animais , Cricetinae , Dilatação e Curetagem , Feminino , Humanos , Pessoa de Meia-Idade , Gravidez , Primeiro Trimestre da Gravidez , CoelhosRESUMO
Normal anthropometric standards of birth weight and birth length are presented for newborn boys and girls in the GDR between 28 and 44 weeks' gestational age. Newborns with uncertain duration of gestation, multiple births, malformations and stillbirths have been excluded. It is directed to necessity of regional standards.
Assuntos
Peso ao Nascer , Peso Corporal , Recém-Nascido , Antropologia Física , Feminino , Alemanha Oriental , Idade Gestacional , Humanos , MasculinoRESUMO
Platelet activating factor (PAF) primes vascular actions of mediators such as histamine and stimulates human umbilical vein endothelial cells (HUVECs) to produce prostacyclin (PGI2), which is important for the regulation of vascular tone, perfusion and hemostasis. We demonstrate that pretreatment of HUVECs with PAF enhances thrombin- or histamine-induced rises of cytosolic free Ca(++)-concentration and subsequent Ca(++)-dependent PGI2-synthesis. Inhibition of Ca(++)-influx and PGI2-formation by SKF96365 (blocker of receptor-operated Ca(++)-channels) in PAF-treated cells indicates that the enhancement of PGI2-synthesis by PAF is due to sensitization of Ca(++)-entry. This suggests cooperative effects of PAF on activation processes induced by thrombin or histamine in HUVECs.
Assuntos
Cálcio/metabolismo , Endotélio Vascular/metabolismo , Epoprostenol/biossíntese , Fator de Ativação de Plaquetas/farmacologia , 6-Cetoprostaglandina F1 alfa/análise , 6-Cetoprostaglandina F1 alfa/metabolismo , Células Cultivadas , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Fura-2 , Histamina/farmacologia , Humanos , Imidazóis/farmacologia , Cinética , Inibidores da Agregação Plaquetária/farmacologia , Espectrometria de Fluorescência , Trombina/farmacologia , Veias UmbilicaisRESUMO
HISTORY: A 65-year-old man had noted a tumor of the right lower leg that had progressively grown over the last twenty years. He had a dyspnoea on insignificant movement and was relatively immobile because of the extent of the tumor. The tumor had been diagnosed as a Klippel-Trenaunay syndrome. INVESTIGATIONS: Laboratory investigations suggested a hypochromic and microcytic anaemia and an inflammatory constellation. The tumor had no av-fistulas on ultrasonography and angiography, but there were many pathological arteries and tumor nodes. The tumor nodes had been seen also on MRI-biopsy suggested a neurogenic sarcoma. DIAGNOSIS AND TREATMENT: Amputation of the leg was necessary. The histological diagnosis was neurofibrosarcoma with extensive necrotic areas and Recklinghausen disease. Investigation did not reveal any metastasis. Postoperatively the anaemia regressed and the patient learned to walk with a prosthesis. CONCLUSIONS: This history shows the problem of separating clearly the two hereditary diseases. Often there is a different clinical picture in everyday life. One must consider the definitely higher risk of malignant tumors of patients with neurofibromatosis. Ultrasonography is a non-invasive method that can provide morphological information on soft parts and pathology of the vessels. It facilitates the classification of such.
Assuntos
Neurofibromatose 1/complicações , Neurofibrossarcoma/complicações , Idoso , Amputação Cirúrgica , Membros Artificiais , Diagnóstico Diferencial , Humanos , Síndrome de Klippel-Trenaunay-Weber/diagnóstico , Perna (Membro)/cirurgia , Masculino , Neurofibromatose 1/diagnóstico por imagem , Neurofibromatose 1/patologia , Neurofibromatose 1/cirurgia , Neurofibrossarcoma/diagnóstico por imagem , Neurofibrossarcoma/patologia , Neurofibrossarcoma/cirurgia , Resultado do Tratamento , UltrassonografiaRESUMO
The blocker of receptor-mediated calcium entry SK&F 96365 was used to evaluate the contribution of calcium influx to the formation of biologically active endothelial prostanoids and endothelium-derived relaxing factor (EDRF). SK&F 96365 inhibited histamine-stimulated calcium entry into human umbilical vein endothelial cells but not its discharge from intracellular stores as determined spectrofluorometrically by changes of intracellular calcium concentration in fura-2-loaded cells. Concordantly, SK&F 96365 inhibited histamine-induced endothelial synthesis of 6-keto-prostaglandin F1 alpha and thromboxane B2 in a dose-dependent manner. To assess the functional significance of endothelial formation of prostacyclin and EDRF to platelets, the cAMP- and cGMP-dependent phosphorylation of two platelet proteins, rap1B and a 50-kD vasodilator-stimulated phosphoprotein (VASP), was analyzed in coincubation experiments of endothelial cells with platelets. Autacoids released by histamine-stimulated endothelial cells caused the phosphorylation of rap1B and VASP in platelets, which was only partly inhibited by either indomethacin or NG-monomethyl-L-arginine but was almost completely suppressed by SK&F 96365. The concomitant endothelial release of thromboxane A2 had no effect on protein kinase C- and calcium-dependent phosphorylation of platelet proteins. The results demonstrate that blockade of receptor-mediated calcium entry by SK&F 96365 markedly reduced the release of biologically active prostacyclin and EDRF from endothelial cells. Thus, calcium influx but not calcium release from intracellular stores plays a critical role in the receptor-stimulated formation and liberation of prostacyclin and EDRF in endothelial cells.
Assuntos
Autacoides/biossíntese , Cálcio/metabolismo , Moléculas de Adesão Celular , Animais , Plaquetas/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Células Cultivadas , Técnicas Citológicas , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Histamina/farmacologia , Humanos , Técnicas In Vitro , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos , Fosfoproteínas/metabolismo , Fosforilação , Prostaglandinas/metabolismo , Suínos , Proteínas rap de Ligação ao GTPRESUMO
During endothelial cell activation, alpha-thrombin elicits both Ca2+ release from internal stores and influx of external Ca2+ across the plasma membrane. The mechanisms of alpha-thrombin-induced Ca2+ entry into endothelial cells are unclear. Therefore, effects of the specific tyrosine kinase inhibitor herbimycin A on protein tyrosine phosphorylation and on intracellular Ca2+ transients were studied in alpha-thrombin-stimulated human umbilical vein endothelial cells. alpha-Thrombin caused significant tyrosine phosphorylation of mainly two proteins and evoked typical biphasic changes of free cytosolic Ca2+ concentration. We show that 24 h pretreatment with herbimycin A inhibited alpha-thrombin-induced endothelial protein tyrosine phosphorylation. Moreover, herbimycin A significantly attenuated alpha-thrombin-induced Ca2+ influx but not release from internal stores. The data suggest that protein tyrosine phosphorylation by alpha-thrombin is involved in the regulation of alpha-thrombin-induced Ca2+ influx into endothelial cells.
Assuntos
Cálcio/metabolismo , Endotélio Vascular/efeitos dos fármacos , Quinonas/farmacologia , Tirosina/metabolismo , Benzoquinonas , Células Cultivadas , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Ativação Enzimática , Humanos , Transporte de Íons/efeitos dos fármacos , Lactamas Macrocíclicas , Fosforilação , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/metabolismo , Rifabutina/análogos & derivados , Trombina/farmacologiaRESUMO
Dihydropyridine (DHP) calcium channel blockers are widely used in treatment of coronary artery disease. To evaluate the specific role of L-type calcium channels in the antianginal and possibly antiatherosclerotic properties of DHP inhibitors, we examined the effects of a 1,4-DHP agonist and antagonist on angiotensin II (ANG II)- and serum-stimulated calcium influx and proliferation of human coronary smooth muscle cells (cSMC). Fluorometry of fura-2 was used to measure changes in free cytosolic Ca2+ concentration ([Ca2+]i) in cSMC after short- and long-term pretreatment with the calcium agonist Bay K 8644 or the antagonist nitrendipine, respectively. Proliferative activity was quantified during exponential growth in serum-supplemented medium with or without both DHPs. Short- and long-term pretreatment with Bay K 8644 increased basal [Ca2+]i significantly in resting cells and augmented ANG II- and serum-induced sustained [Ca2+]i responses. Concordantly, proliferation rate was increased. In contrast, nitrendipine had no significant effect on basal or stimulated [Ca2+]i after short-term treatment, but decreased [Ca2+]i after 24-h incubation, attenuated the plateau phase of ANG II- and serum-evoked [Ca2+]i transients, and reduced proliferative activity of these cells. The results indicate that 1,4-DHPs modulate ANG II- and serum-induced Ca2+ influx in cSMC. Thus, L-type calcium channels may contribute to [Ca2+]i transients evoked by ANG II and serum. Moreover, the modulating effects of both DHPs on proliferative activity suggest involvement of DHP-sensitive calcium channels. Calcium influx through L-type channels may be one of the mechanisms that determine responsiveness to vasoconstrictors and proliferative activity of human cSMC.
Assuntos
Canais de Cálcio/fisiologia , Cálcio/metabolismo , Vasos Coronários/citologia , Vasos Coronários/metabolismo , Músculo Liso Vascular/citologia , Músculo Liso Vascular/metabolismo , Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , Angiotensina II/farmacologia , Fenômenos Fisiológicos Sanguíneos , Divisão Celular/efeitos dos fármacos , Células Cultivadas , Humanos , Nitrendipino/farmacologiaRESUMO
PIP: Successful treatment of intrauterine fetal death by intravenous administration of (PGF2alpha) prostaglandin F2alpha in 20 patients (gestational age 22-40 weeks) and of PGE2 in 6 patients (gestational age 24-36 weeks) is reported. Infusion of 5-20 mcg PGF2alpha/minute and of 0.5-2.0 mcg PGE2/minute resulted in regular uterine contractions within the first 2 hours. The average dosage of PGF2alpha was 7.06 mg in cephalic presentations (infusion time=7 hours, 2 minutes) and 23.4 mg in anomalous presentations (infusion time=16 hours, 54 minutes). The average dose of PGE2 was 1.17 mg (infusion time=9 hours, 23 minutes). Coagulation investigations were performed before, during, and after PG infusion. These investigations suggest that the coagulation potential of patients with intratuerine fetal death by intravenous PG administration is not influenced to any extent. Few undesirable side effects were seen using this PG. We consider that the intravenous PG application for the induction of labor in intrauterine fetal death is a useful method because of the effectiveness and few undersirable side effects. (author's)^ieng