RESUMEN
Understanding cellular and molecular mechanisms induced by hypoxic stress is crucial to reduce blood-brain barrier (BBB) disruption in some neurological diseases. Since the brain is a complex organ, it makes the interpretation of in vivo data difficult, so BBB studies are often investigated using in vitro models. However, the investigation of hypoxia in cellular pathways is complex with physical hypoxia because HIF-1α (factor induced by hypoxia) has a short half-life. We had set up an innovative and original method of induction of hypoxic stress by hydralazine that was more reproducible, which allowed us to study its impact on an in vitro BBB model. Our results showed that hydralazine, a mimetic agent of the hypoxia pathway, had the same effect as physical hypoxia, with few cytotoxicity effects on our cells. Hypoxic stress led to an increase of BBB permeability which corresponded to an opening of our BBB model. Study of tight junction proteins revealed that this hypoxic stress decreased ZO-1 but not occludin expression. In contrast, cells established a defence mechanism by increasing expression and activity of their efflux transporters (Pgp and MRP-1). This induction method of hypoxic stress by hydralazine is simple, reproducible, controllable and suitable to understand the cellular and molecular mechanisms involved by hypoxia on the BBB.
Asunto(s)
Barrera Hematoencefálica/efectos de los fármacos , Barrera Hematoencefálica/metabolismo , Hidralazina/farmacología , Hipoxia/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Estrés Oxidativo/efectos de los fármacos , Animales , Transporte Biológico , Biomarcadores , Supervivencia Celular/efectos de los fármacos , Hidralazina/toxicidad , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Redes y Vías Metabólicas , Permeabilidad , Ratas , Proteínas de Uniones Estrechas/metabolismoRESUMEN
Currently there are no effective therapies available for the excruciating neuropathic pain that develops after spinal cord injuries (SCI). As such, a great deal of effort is being put into the investigation of novel therapeutic targets that can alleviate this pain. One such target is acrolein, a highly reactive aldehyde produced as a byproduct of oxidative stress and inflammation that is capable of activating the transient receptor potential ankyrin 1 (TRPA1) cation channel, known to be involved in the transmission and propagation of chronic neuropathic pain. One anti-acrolein agent, hydralazine, has already been shown to reduce neuropathic pain behaviors and offer neuroprotection after SCI. This study investigates another acrolein scavenger, phenelzine, for its possible role of alleviating sensory hypersensitivity through acrolein suppression. The results show that phenelzine is indeed capable of attenuating neuropathic pain behaviors in acute, delayed, and chronic administration schedules after injury in a rat model of SCI. In addition, upon the comparison of hydralazine to phenelzine, both acrolein scavengers displayed a dose-dependent response in the reduction of acrolein in vivo. Finally, phenelzine proved capable of providing locomotor function recovery and neuroprotection of spinal cord tissue when administered immediately after injury for 2 weeks. These results indicate that phenelzine may be an effective treatment for neuropathic pain after SCI and likely a viable alternative to hydralazine. We have shown that phenelzine can attenuate neuropathic pain behavior in acute, delayed, and chronic administration in post-SCI rats. This was accompanied by a dose-dependent reduction in an acrolein metabolite in urine and an acrolein adduct in spinal cord tissue, and the suppression of TRPA1 over-expression in central and peripheral locations post-trauma. Acrolein scavenging might be a novel therapeutic strategy to reduce post-SCI neuropathic pain.
Asunto(s)
Hiperalgesia/tratamiento farmacológico , Neuralgia/tratamiento farmacológico , Fenelzina/farmacología , Recuperación de la Función/efectos de los fármacos , Traumatismos de la Médula Espinal/tratamiento farmacológico , Animales , Conducta Animal/efectos de los fármacos , Contusiones/tratamiento farmacológico , Modelos Animales de Enfermedad , Hidralazina/toxicidad , Masculino , Neuralgia/metabolismo , Ratas Sprague-Dawley , Traumatismos de la Médula Espinal/metabolismoRESUMEN
Multiple drug administration is an important aspect of clinical practice particularly in specific physiological situation such as in neonates, elderly or pregnancy, since in all such situations, possibility of unwanted effects increases due to altered body physiology. In present study, the teratogenic effects of multiple drug administration risperidone, meclizine/pyridoxine and hydralazine have been compared with the teratogenic effects of individual drugs in pregnant mice. Moreover the role of folic acid and α-tocopherol if any had also been investigated in reducing the teratogenic effects of these drugs in combinations.
Asunto(s)
Anomalías Inducidas por Medicamentos/prevención & control , Antieméticos/toxicidad , Antihipertensivos/toxicidad , Evaluación Preclínica de Medicamentos/estadística & datos numéricos , Piridoxina/uso terapéutico , Risperidona/toxicidad , alfa-Tocoferol/uso terapéutico , Animales , Antieméticos/administración & dosificación , Antihipertensivos/administración & dosificación , Evaluación Preclínica de Medicamentos/métodos , Interacciones Farmacológicas , Femenino , Peso Fetal/efectos de los fármacos , Hidralazina/administración & dosificación , Hidralazina/toxicidad , Meclizina/administración & dosificación , Meclizina/toxicidad , Ratones , Risperidona/administración & dosificación , MortinatoRESUMEN
The purpose of this study was to correlate the histologic changes in the heart to serum cardiac troponin I (cTnI) concentrations assayed with the Erenna Immunoassay System in Wistar rats (Crl:Wi[Han]) using the hydralazine model of cardiotoxicity. A single dose of hydralazine caused an increase of cTnI concentrations at six hours post-dose, followed by a sharp decrease at twenty-four hours and a return to baseline at forty-eight hours. The second dose of hydralazine caused a smaller magnitude increase in cTnI concentrations at six hours as compared to the first dose. Also, cTnI concentrations returned to baseline at twenty-four hours after the second dose. The increased cTnI concentrations coincided with acute myocardial necrosis at histology. However, increased cTnI concentrations in the absence of microscopic lesions were identified in several rats. As cTnI concentrations decreased, microscopic changes in the heart matured to cardiomyophagy. In conclusion, the increases in cTnI concentrations six hours after the administration of hydralazine were indicative of a myocardial damage that did not consistently have a microscopic correlate. However, the window of increased cTnI concentrations was short, and only microscopic evaluation of the heart detected the damage at twenty-four to forty-eight hours after the episode of acute myocardial necrosis.
Asunto(s)
Hidralazina/toxicidad , Inmunoensayo/métodos , Miocardio/metabolismo , Troponina I/metabolismo , Animales , Relación Dosis-Respuesta a Droga , Corazón/efectos de los fármacos , Masculino , Miocardio/patología , Necrosis , Ratas , Ratas Wistar , Pruebas de ToxicidadRESUMEN
Idiosyncratic drug reactions (IDRs) represent a major clinical problem, and at present, the mechanisms involved are still poorly understood. One animal model that we have used for mechanistic studies of IDRs is penicillamine-induced autoimmunity in Brown Norway (BN) rats. Previous work in our lab found that macrophage activation preceded the clinical autoimmune syndrome. It is thought that one of the interactions between T cells and macrophages involves reversible Schiff base formation between an amine on T cells and an aldehyde on macrophages, but the identity of the molecules involved is unknown. It is also known that penicillamine reacts with aldehyde groups to form a thiazolidine ring, which unlike a Schiff base, is essentially irreversible. Such binding could lead to macrophage activation. Generalized macrophage activation could lead to the observed autoimmune reaction. Hydralazine and isoniazid also react with aldehydes to form stable hydrazones, and they also cause an autoimmune lupus-like syndrome. In this study, isolated spleen cells from male BN rats were incubated with biotin-aldehyde-reactive probe (ARP, a hydroxylamine), biotin-hydrazide, or D-penicillamine. At all concentrations, ARP, hydrazide, and penicillamine preferentially "stained" macrophages relative to other spleen cells. In addition, preincubation of cells with penicillamine or hydralazine decreased ARP staining of macrophages, which further indicates that most of the ARP binding to macrophages involves binding to aldehyde groups. This provides support for the hypothesis that the interaction between aldehyde-containing signaling molecules on macrophages and penicillamine could be the initial event of penicillamine-induced autoimmunity. Several of the proteins to which ARP binds were identified, and some such as myosin are attractive candidates to mediate macrophage activation.
Asunto(s)
Macrófagos/efectos de los fármacos , Penicilamina/química , Aldehídos/química , Animales , Autoinmunidad , Biotina/química , Hidralazina/farmacología , Hidralazina/toxicidad , Macrófagos/química , Macrófagos/inmunología , Masculino , Penicilamina/farmacología , Penicilamina/toxicidad , Unión Proteica , Proteínas/química , Ratas , Ratas Endogámicas BN , Bases de Schiff/químicaRESUMEN
Long-term treatment of hypertensive disorders with hydralazine has resulted in some patients developing hepatitis and lupus erythematosus, an autoimmune syndrome. The concentration of hydralazine required to cause 50% cytotoxicity in 2 h (LC(50)) toward isolated rat hepatocytes was found to be 8 mM. Cytotoxicity was delayed by the P450 inhibitor, 1-aminobenzotriazole, suggesting that P450 catalyzed the formation of toxic metabolites from hydralazine. No hydralazine-induced oxidative stress was apparent as there was little effect on hepatocyte lipid peroxidation, protein carbonyl formation, intracellular H(2)O(2), or hepatocyte GSH levels and no effect of butylated hydroxyanisole (BHA) on cytotoxicity. Drug-induced hepatotoxicity in vivo has often been attributed to infiltrating inflammatory cells, for example, neutrophils or resident Kupffer cells whose NADPH oxidase generates H(2)O(2), when activated. The effect of a nontoxic continuous infusion of H(2)O(2) on hydralazine cytotoxicity was investigated. It was found that H(2)O(2) increased hepatocyte susceptibility to hydralazine 4-fold (LC(50), 2 mM). Cytotoxicity was still prevented by the P450 inhibitor but now involved some oxidative stress as shown by increased protein carbonyls, endogenous H(2)O(2), and GSH oxidation. Lipid peroxidation was not increased, and cytotoxicity was not inhibited by BHA. Cytotoxicity, however, was inhibited by 4-hydroxy-2,2,6,6-tetramethylpiperidene-1-oxyl (TEMPOL), a ROS scavenger. Because neutrophils or Kupffer cells release myeloperoxidase on activation, the effect of adding peroxidase to the hepatocytes exposed to H(2)O(2) on hydralazine cytotoxicity was investigated. It was found that peroxidase/H(2)O(2) increased hepatocyte susceptibility to hydralazine 80-fold (LC 50, 0.1 mM). Furthermore, cytotoxicity occurred following extensive oxidative stress that included lipid peroxidation, and cytotoxicity that was now prevented by the antioxidant BHA. These results indicate that three cytotoxic pathways exist for hydralazine: a P450-catalyzed pathway not involving oxidative stress, a P450/H(2)O(2)-catalyzed oxidative stress-mediated cytotoxic pathway not involving lipid peroxidation, and a peroxidase/H(2)O(2)-catalyzed lipid peroxidation-mediated cytotoxic pathway.
Asunto(s)
Antihipertensivos/toxicidad , Hepatocitos/efectos de los fármacos , Hidralazina/toxicidad , Estrés Oxidativo , Animales , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Glutatión/metabolismo , Disulfuro de Glutatión/metabolismo , Hepatocitos/citología , Hepatocitos/metabolismo , Peróxido de Hidrógeno/metabolismo , Peroxidación de Lípido , Masculino , Peroxidasa/metabolismo , Carbonilación Proteica , Ratas , Ratas Sprague-Dawley , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismoRESUMEN
Accumulating evidence indicates that epigenetic alterations contribute to exacerbated activation or deregulation of the mechanisms that maintain tolerance to self-antigens in patients with lupus, a systemic autoimmune disease that can be triggered by medications taken to treat a variety of conditions. Here, we tested the effect of hydralazine, an antihypertensive drug that triggers lupus, on receptor editing, a chief mechanism of B lymphocyte tolerance to self-antigens. Using mice expressing transgenic human Igs, we found that hydralazine impairs up-regulation of RAG-2 gene expression and reduces secondary Ig gene rearrangements. Receptor editing was also partially abolished in a dose-dependent manner by a specific inhibitor of MEK1/2. Adoptive transfer of bone marrow B cells pretreated with hydralazine or with a MEK inhibitor to naïve syngeneic mice resulted in autoantibody production. We conclude that, by disrupting receptor editing, hydralazine subverts B lymphocyte tolerance to self and contributes to generation of pathogenic autoreactivity. We also postulate that inhibition of the Erk signaling pathway contributes to the pathogenesis of hydralazine-induced lupus and idiopathic human lupus.
Asunto(s)
Linfocitos B/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Hidralazina/toxicidad , Lupus Eritematoso Sistémico/inducido químicamente , Lupus Eritematoso Sistémico/inmunología , Autotolerancia/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Animales , Autoanticuerpos/biosíntesis , Autoanticuerpos/efectos de los fármacos , Linfocitos B/inmunología , Proteínas de Unión al ADN/metabolismo , Flavonoides/farmacología , Regulación de la Expresión Génica/inmunología , Alotipos de Inmunoglobulinas/efectos de los fármacos , Alotipos de Inmunoglobulinas/genética , MAP Quinasa Quinasa 1/antagonistas & inhibidores , MAP Quinasa Quinasa 2/antagonistas & inhibidores , Ratones , Ratones Transgénicos , Autotolerancia/inmunología , Transducción de Señal/inmunologíaRESUMEN
OBJECTIVE: The objectives were two-fold: (1) determine whether the use of hydralazine as antihypertensive therapy during obesity development exacerbated obesity-related cardioacceleration and hormonal abnormalities; (2) determine whether the absence of hypertension in obesity attenuated obesity-related abnormalities in hemodynamics, cardiac hypertrophy, and hormonal profile. DESIGN: Female New Zealand White rabbits were divided into lean control (n=12), lean hydralazine-treated (n=9), obese control (n=11), and obese hydralazine-treated (n=8) groups. Pretreatment mean blood pressure (BP) and heart rate (HR) were determined using telemetry. Pretreatment BP was maintained during 12 weeks of obesity development using hydralazine. MEASUREMENTS: Chronically measured BP and HR; plasma/blood volume; wet and dry ventricular weights; body fat/water; and hormonal profile (plasma renin activity, aldosterone, cortisol, atrial natriuretic peptide, adrenaline, and noradrenaline). RESULTS: Hydralazine treatment in obese animals attenuated obesity-related renin-angiotensin system (RAS) activation. In contrast, RAS was activated in lean hydralazine, as indicated by increased plasma aldosterone. The absence of hypertension in obese hydralazine did not result in attenuation of cardioacceleration, cardiac hypertrophy, or intravascular volumes. CONCLUSIONS: Hydralazine treatment in obese rabbits did not exacerbate obesity-related cardiovascular and hormonal alterations. Cardioacceleration and cardiac hypertrophy persisted in obese hydralazine despite BP control, suggesting hypertension-independent effects of obesity on these variables. Hydralazine's effects on RAS activation differed in lean and obese rabbits, suggesting that the systemic effects of hydralazine as a control therapy in evaluation of antihypertensive medications may differ depending on the underlying pathology.
Asunto(s)
Antihipertensivos/uso terapéutico , Hidralazina/uso terapéutico , Hipertensión/tratamiento farmacológico , Obesidad/complicaciones , Animales , Antihipertensivos/toxicidad , Biometría , Presión Sanguínea/efectos de los fármacos , Cardiomegalia/etiología , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Hormonas/sangre , Hidralazina/toxicidad , Hipertensión/etiología , Obesidad/sangre , Obesidad/fisiopatología , Conejos , Sistema Renina-Angiotensina/efectos de los fármacosRESUMEN
DNA methylation plays an essential role in maintaining T-cell function. A growing body of literature indicates that failure to maintain DNA methylation levels and patterns in mature T cells can result in T-cell autoreactivity in vitro and autoimmunity in vivo. Defective maintenance of DNA methylation may be caused by drugs such as procainamide or hydralazine, or failure to activate the genes encoding maintenance DNA methyltransferases during mitosis, resulting in the development of a lupus-like disease or perhaps other autoimmune disorders. This paper reviews the evidence supporting a role for abnormal T-cell DNA methylation in causing autoimmunity in an animal model of drug-induced lupus, and discusses some of the mechanisms involved. T cells from patients with active lupus have evidence for most if not all of the same methylation abnormalities, suggesting that abnormal DNA methylation plays a role in idiopathic human lupus as well.
Asunto(s)
Enfermedades Autoinmunes/metabolismo , Metilación de ADN , Animales , Enfermedades Autoinmunes/etiología , Enfermedades Autoinmunes/inmunología , Autoinmunidad/efectos de los fármacos , Azacitidina/toxicidad , Comunicación Celular/efectos de los fármacos , Comunicación Celular/inmunología , Metilación de ADN/efectos de los fármacos , Humanos , Hidralazina/toxicidad , Técnicas In Vitro , Lupus Eritematoso Sistémico/etiología , Modelos Inmunológicos , Procainamida/toxicidad , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunología , Linfocitos T/metabolismoRESUMEN
The influence of metabolic activation on the genotoxic activity of the antihypertensive drugs hydralazine and dihydralazine was investigated. An in vitro micronucleus test for estimating the genotoxic activity of these drugs was used. The results obtained indicated that hydralazine and dihydralazine induce micronuclei formation in L929 cells. When L929 cell cultures were treated with drugs together with liver membrane fraction (S9 fraction) from polychlorinated biphenyl (Aroclor 1254) induced rat liver, the number of micronucleated cells decrease, however, almost to the level found in control cultures. The experiments with modified S9 mix allow the conclusion that the antioxidant enzymes catalase and superoxide dismutase present in S9 liver fraction play a role in the protection of cells from the genotoxic action of hydralazine and dihydralazine.
Asunto(s)
Antihipertensivos/toxicidad , Dihidralazina/toxicidad , Hidralazina/toxicidad , Mutágenos/toxicidad , Animales , Antihipertensivos/metabolismo , Arocloros/farmacología , Biotransformación , Catalasa/antagonistas & inhibidores , Catalasa/metabolismo , Línea Celular , Tejido Conectivo/efectos de los fármacos , Tejido Conectivo/metabolismo , Tejido Conectivo/patología , Dihidralazina/metabolismo , Activación Enzimática , Calor , Hidralazina/metabolismo , Masculino , Ratones , Pruebas de Micronúcleos , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Mutágenos/metabolismo , Ratas , Ratas Wistar , Superóxido Dismutasa/antagonistas & inhibidores , Superóxido Dismutasa/metabolismoRESUMEN
The mutagenic activity of two antihypertensive drugs, hydralazine and dihydralazine was investigated in oxyR- proficient (TA104) and -deficient (TA4125) Salmonella typhimurium strains showing different ability to induce proteins involved in protection of the cells against oxidative damage. The results of the Ames test demonstrated that dihydralazine, in contrast to hydralazine, was mutagenic for oxyR- strain at concentrations that were nonmutagenic for oxyR+ strain. The scavenger of superoxide anion, superoxide dismutase decreased in both strains the number of revertants induced by dihydralazine but not by hydralazine. The results may suggest that active oxygen species generated by dihydralazine contribute to its mutagenicity.
Asunto(s)
Antihipertensivos/toxicidad , Proteínas de Unión al ADN , Dihidralazina/toxicidad , Hidralazina/toxicidad , Mutágenos/toxicidad , Proteínas Represoras/genética , Salmonella typhimurium/genética , Factores de Transcripción/genética , Daño del ADN , Estrés Oxidativo , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/metabolismo , Superóxidos/metabolismoRESUMEN
Urocortin, a newly isolated 40-amino-acid mammalian peptide homologous to corticotropin-releasing hormone (CRH), activates both CRH type 1 and 2 receptors, but may be an endogenous ligand for CRH receptor type 2. Urocortin given systemically inhibited heat-induced paw edema in the rat, and was therefore ascribed anti-inflammatory properties. We examined the effects of urocortin in the carrageenin-induced subcutaneous inflammation model. Rats were treated with urocortin 200 (n = 6) or 20 nmol/kg (n = 6); inflammatory exudates were reduced by approximately 30% compared to controls (n = 7) at both doses. However, since subcutaneous urocortin has been shown to reduce arterial blood pressure, we tested the hypothesis that its antiedema and antiextravasatory effects were secondary to arterial hypotension. Therefore, we examined the parallel effects of urocortin- and hydralazine-induced hypotension on acute inflammation induced by carrageenin in the rat. Rats were treated with subcutaneous carrageenin and control injections (n = 8), carrageenin and urocortin (20 nmol/kg, n = 9), or carrageenin and intraperitoneal hydralazine (10 mg/kg, n = 8). Mean arterial blood pressure was measured hourly for 7 h in 12 animals, and after 2 h, the nadir of treatment, in a further 13 animals. Rats were then sacrificed, and the inflammatory exudate volume and leukocyte count were measured. Mean exudate volumes were reduced from 4.8 +/- 0.5 ml (controls) to 2.4 +/- 0.3 ml (p = 0.004) and 2.9 +/- 0.6 ml (p = 0.007) in urocortin- and hydralazine-treated animals, respectively. Urocortin and hydralazine both produced a significant fall in blood pressure compared to controls, with mean arterial pressure 2 h after carrageenin injection falling to 51.0 +/- 4.1 (p < 0.001) and 34.6 +/- 4.6 (p < 0.001) vs. 92.9 +/- 3.7 mm Hg in controls, respectively. A significant positive correlation was noted between blood pressure and inflammatory exudate volume (r = 0. 52, p = 0.007). As both hydralazine and urocortin lowered blood pressure and inflammatory exudate volume, we suggest that the anti-inflammatory effects of urocortin and related neuropeptides may be nonspecific, acting through hypotension rather than through direct anti-inflammatory mechanisms. The use of inflammatory models which rely on extravasation may be inappropriate for the study of substances that produce hypotension.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Hormona Liberadora de Corticotropina/fisiología , Hipotensión/complicaciones , Inflamación/fisiopatología , Receptores de Hormona Liberadora de Corticotropina/efectos de los fármacos , Animales , Antiinflamatorios no Esteroideos/toxicidad , Presión Sanguínea/efectos de los fármacos , Carragenina/toxicidad , Hormona Liberadora de Corticotropina/farmacología , Hormona Liberadora de Corticotropina/toxicidad , Edema/prevención & control , Exudados y Transudados/química , Exudados y Transudados/citología , Pie , Hidralazina/toxicidad , Hipotensión/inducido químicamente , Inflamación/complicaciones , Inflamación/tratamiento farmacológico , Recuento de Leucocitos/efectos de los fármacos , Masculino , Ratas , Ratas Sprague-Dawley , Receptores de Hormona Liberadora de Corticotropina/fisiología , UrocortinasRESUMEN
The nature of genotoxic and cytotoxic effects induced by hydralazine was analyzed taking into account possible protection of cells by catalase, superoxide dismutase and dimethyl sulfoxide. For the experiments designed to evaluate the influence of scavengers on the genotoxicity expressed as the SOS induction factor the E. coli PQ37 strain was used. The cytotoxic effects were investigated in V3 cells cultured in vitro. The genotoxicity and cytotoxicity of hydralazine were suppressed by catalase in a dose-dependent manner but they were enhanced by superoxide dismutase. No protective effect of dimethyl sulfoxide was observed. Our results indicate that H2O2 plays an essential role in the genotoxicity and cytotoxicity of hydralazine.
Asunto(s)
Hidralazina/toxicidad , Respuesta SOS en Genética/efectos de los fármacos , Animales , Catalasa/farmacología , Línea Celular , Chlorocebus aethiops , Dimetilsulfóxido/farmacología , Interacciones Farmacológicas , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Depuradores de Radicales Libres/farmacología , Riñón/efectos de los fármacos , Superóxido Dismutasa/farmacologíaRESUMEN
The genotoxicity of antihypertensive drugs, hydralazine, dihydralazine and binazine was assessed on the base of their capacity to induce micronuclei in L929 cell line. In our previous investigations we indicated that these drugs did not induce micronuclei in bone marrow polichromatic erythrocytes in PZH SFISS mice. Present results show that hydralazine and dihydralizine can induce micronuclei in vitro and that this effect depends on time of exposure and the concentration of drug.
Asunto(s)
Antihipertensivos/toxicidad , Dihidralazina/toxicidad , Hidralazina/toxicidad , Todralazina/toxicidad , Animales , Línea Celular/efectos de los fármacos , Ratones , Pruebas de MicronúcleosRESUMEN
The hepatic and renal toxicity associated with hydrazine treatment has been linked to free radical damage resulting from oxidative metabolism by cytochrome P4502E1 (CYP2E1). Despite this association, there has been little characterization of the effects of hydrazine treatment on the expression of hepatic and renal CYP2E1 or glutathione-S-transferase-alpha (GST-alpha), an enzyme responsible for catalyzing the conjugation of free radicals with reduced glutathione. Therefore, the effects of treatment with hydrazine or one of the therapeutic hydrazines phenelzine and hydralazine on rat hepatic and renal CYP2E1 and GST-alpha expression were investigated. Adult male Sprague-Dawley rats were treated with 0.9% saline vehicle (1 dose ip), hydrazine (100 mg/kg ip), phenelzine (100 mg/kg ip), or hydralazine (25 mg/kg ip). CYP2E1 mRNA and protein levels were monitored by Northern and immunoblot analyses, respectively, and GST-alpha Ya and Yc subunit levels were determined by immunoblot analysis. Hydralazine administration caused a significant (approximately 159%) increase in renal GST-alpha subunit expression. In addition, hydrazine and phenelzine treatment produced substantial elevations (approximately 464% and 566%, respectively) in renal CYP2E1 protein, whereas hydralazine administration did not alter renal CYP2E1 expression. Changes in rat hepatic GST-alpha Ya or Yc subunit levels after treatment with hydrazines phenelzine, or hydralazine were not statistically significant. Similarly, hepatic CYP2E1 levels were not significantly altered after treatment with hydrazine, phenelzine, or hydralazine. Northern blot analysis revealed that the observed increases in renal CYP2E1 protein levels after treatment with hydrazine or phenelzine were not accompanied by concomitant increases in CYP2E1 mRNA. These results suggest that treatment with hydrazine or the therapeutic hydrazine phenelzine significantly increases the expression of rat renal CYP2E1 protein, and that the molecular mechanism responsible for these effects are posttranscriptional in nature.
Asunto(s)
Citocromo P-450 CYP2E1/biosíntesis , Hidralazina/farmacología , Hidrazinas/farmacología , Riñón/enzimología , Hígado/enzimología , Fenelzina/farmacología , Animales , Northern Blotting , Citocromo P-450 CYP2E1/genética , Glutatión Transferasa/biosíntesis , Hidralazina/toxicidad , Hidrazinas/toxicidad , Riñón/efectos de los fármacos , Hígado/efectos de los fármacos , Masculino , Fenelzina/toxicidad , ARN Mensajero/análisis , Ratas , Ratas Sprague-DawleyRESUMEN
Early focal myocardial lesions in rats induced by five cardiotoxic compounds were histopathologically observed 1 hr and 4 hr after a single intravenous injection with 1/10 LD50 and LD50. The lesions were observed 1 hr and 4 hr after the treatment with LD50 of isoproterenol (ISP), 4 hr with 1/10 LD50 of ISP, 4 hr with LD50 of hydralazine (HYD), caffeine (CAF) and cyclophosphamide (CYC), but not with adriamycin (ADR). The lesions consisted of homogeneously intensely eosinophilic staining, contraction band formation and fragmentation of cardiac muscle fibers. The lesions were interspersed in the inner one third of the left ventricular walls including the papillary muscles with ISP, HYD and CAF, and were all over the ventricular myocardium with CYC.
Asunto(s)
Cafeína/toxicidad , Ciclofosfamida/toxicidad , Doxorrubicina/toxicidad , Hidralazina/toxicidad , Isoproterenol/toxicidad , Miocardio/patología , Animales , Corazón/efectos de los fármacos , Dosificación Letal Mediana , Masculino , Contracción Miocárdica , Ratas , Ratas Sprague-DawleyRESUMEN
Hydralazine (H) induces hypotension accompanied by cardiac stimulation due to activation of the arterial baroreflex. Both clinical and experimental observations suggest, however, that in certain conditions H hypotension can be accompanied by unchanged or even depressed cardiac performance. The present study determined whether varying patterns of heart rate responses could be detected in large populations of conscious normotensive (n = 61) and renal hypertensive (n = 59) rats receiving a single dose of H. These patterns were compared with those of normotensive pentobarbital-anesthetized rats (n = 43). In the three groups, hypotension was accompanied by either tachycardia, unchanged heart rate or bradycardia. Tachycardia was found in 52% of normotensive conscious rats, in 51% of hypertensives and in only 14% of anesthetized animals. Heart rate did not change in 26, 35 and 23%, while bradycardia was detected in 22, 14 and 63%, respectively. These results were explained by postulating the initiation by H of two reflexes with opposite effects on heart rate: the arterial baroreflex producing tachycardia and a cardiac mechanoreceptor reflex producing bradycardia. These reactions would compete with each other, with results depending on their relative sensitivity in a given animal.
Asunto(s)
Antihipertensivos/farmacología , Barorreflejo/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Hidralazina/farmacología , Hipertensión Renal/fisiopatología , Hipotensión/inducido químicamente , Mecanorreceptores/efectos de los fármacos , Vasodilatadores/farmacología , Animales , Antihipertensivos/toxicidad , Barorreflejo/fisiología , Bradicardia/inducido químicamente , Bradicardia/fisiopatología , Femenino , Hidralazina/toxicidad , Hipotensión/fisiopatología , Mecanorreceptores/fisiología , Ratas , Ratas Wistar , Taquicardia/inducido químicamente , Taquicardia/fisiopatología , Vasodilatadores/toxicidadAsunto(s)
Antihipertensivos/toxicidad , Cardiomiopatías/inducido químicamente , Hidralazina/toxicidad , Glándulas Suprarrenales/efectos de los fármacos , Glándulas Suprarrenales/metabolismo , Glándulas Suprarrenales/ultraestructura , Análisis de Varianza , Animales , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Corazón/efectos de los fármacos , Histocitoquímica , Metabolismo de los Lípidos , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/ultraestructura , Masculino , Miocardio/metabolismo , Miocardio/ultraestructura , Ratas , Ratas Wistar , Estrés Fisiológico/inducido químicamente , Estrés Fisiológico/metabolismo , Estrés Fisiológico/patologíaRESUMEN
1-Hydrazinophthalazine [hydralazine (HDZ)] is a hydrazine derivative that is a direct acting vasodilator effective in the treatment of essential hypertension. HDZ is biotransformed by the phase II conjugation enzyme N-acetyltransferase (NAT) forming acetyl HDZ, which spontaneously cyclized to the stable product 3-methyl-s-triazolo- [3,4-alpha]-phthalazine (MTP). Therapeutic use of HDZ has resulted in adverse side effects, specifically a drug-induced systemic lupus erythematosus. Slow acetylators are more likely than rapid acetylators to develop this toxicity. Bacteria expressing different levels of NAT were used to test the hypothesis that acetylation of HDZ decreases its mutagenic potential. The variation in NAT activities was confirmed by incubating bacterial cultures with HDZ, and the formation of MTP was monitored by HPLC. At 1.0 mg/ml HDZ, YG1029 (NAT overexpresser) produced 5.3 times the amount of MTP as TA100 (normal NAT expresser), and this production was linear for 20 hr. In the Salmonella mutagenesis assay, HDZ produced a dose- and strain-dependent increase in the number of revertants observed. Exposure to 4 mg HDZ/plate resulted in 1000 revertants in the overexpressing strain, YG1029, whereas both TA100 and TA100/1,8DNP6, which express normal levels and lack the NAT protein respectively, produced 1600 revertants. Colony hybridization analysis using probes for each of the six possible TA100 reverting mutations was performed to determine the nature of the mutations. The G:C to T:A transversion was the only mutation whose frequency was increased significantly by HDZ. Fifty-four percent of the induced vs. 25% of the spontaneous mutations were C to A transversions.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Antihipertensivos/metabolismo , Antihipertensivos/toxicidad , Hidralazina/metabolismo , Hidralazina/toxicidad , Mutágenos/metabolismo , Mutágenos/toxicidad , Acetilación , Animales , Antihipertensivos/farmacocinética , Arilamina N-Acetiltransferasa/genética , Arilamina N-Acetiltransferasa/metabolismo , Biotransformación , Codón , Hidralazina/farmacocinética , Ratones , Ratones Endogámicos A , Ratones Endogámicos C57BL , Pruebas de Mutagenicidad , Mutágenos/farmacocinética , Mutación , Ftalazinas/metabolismo , Salmonella/efectos de los fármacos , Salmonella/genética , Salmonella/metabolismoRESUMEN
The mutagenicity (Ames test) and genotoxicity (SOS Chromotest) of hydralazine were studied. Hydralazine was found to be genotoxic to E.coli PQ37. In experiments with E.coli MD332 it was genotoxic in responsive temperature (30 degrees C) but not genotoxic in non-responsive temperature (42 degrees C). Hydralazine was mutagenic to S.typhimurium TA100 and TA104 but not mutagenic to TA102. Different active oxygen species scavengers did not influence the genotoxicity and mutagenicity of hydralazine.