RESUMEN
The redox reaction of cytochrome c after modification with peroxynitrite under physiological conditions was investigated. Cytochrome c was treated with a bolus of synthetic peroxynitrite at a sub-millimolar concentration, and then subjected to reduction by superoxide and oxidation by hydrogen peroxide. The ability for the membrane potential formation in the mitochondrial respiratory chain was also evaluated. After the treatment with peroxynitrite, the cytochrome c molecule was mono-nitrated mainly at a tyrosine residue, using liquid chromatography-electrospray ionizing mass spectrometry (LC-ESI-MS) and HPLC. Although the redox capacity of cytochrome c was not affected by the peroxynitrite treatment, the oxidation of ferrocytochrome c to ferricytochrome c by hydrogen peroxide was accelerated. When cytochrome c was treated with peroxynitrite in the presence of 5-methoxytryptamine, an inhibitor for the tyrosine nitration by peroxynitrite, the acceleration of hydrogen peroxide-mediated oxidation was suppressed. It was also found that the formation of membrane potential in the rat liver mitochondria was suppressed when peroxynitrite-treated cytochrome c was used instead of the intact cytochrome c in vitro. From these results, we concluded that the peroxynitrite-treated cytochrome c was nitrated at a tyrosine residue and became more susceptible to oxidation by hydrogen peroxide, concomitantly losing the ability to transfer electrons in the mitochondrial respiratory chain. It is suggested that the peroxynitrite-induced modification of cytochrome c increases the susceptibility to non-physiological oxidants, and may cause dysfunction of mitochondria by suppressing of membrane potential.
Asunto(s)
Grupo Citocromo c/efectos de los fármacos , Ácido Peroxinitroso/farmacología , Animales , Cromatografía Líquida de Alta Presión , Dicroismo Circular , Grupo Citocromo c/química , Transporte de Electrón/efectos de los fármacos , Hidrólisis , Técnicas In Vitro , Masculino , Potenciales de la Membrana , Oxidación-Reducción , Ratas , Ratas Wistar , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría UltravioletaRESUMEN
We used a cardiopulmonary test to assess the physiological benefit of single lead VDD pacing in ten patients (six men, four women; aged 32-84 years, mean 69 years) with atrioventricular block. Maximal symptom-limited treadmill exercise test using a ramp protocol was performed under VDD and VVIR or VVI pacing (VVI) in random sequence. The pacemaker was then programmed to the VDD mode, and Holter ECG was recorded in nine patients. Compared with findings during the VVI, the VDD mode had a greater chronotropic response (mean maximal heart rate, VDD 106 +/- 17 beats/min vs VVI 79 +/- 19 beats/min, P = 0.03), and was associated with prolongation of exercise duration (VDD 11.2 +/- 2.9 minute vs VVI 10.5 +/- 3.1 minute; P = 0.01), and the onset of anaerobic threshold at a higher oxygen uptake (VDD 12.4 +/- 3.4 mL/min per kilogram vs VVI 10.0 +/- 2.1 mL/min per kilogram; P < 0.01). Atrial sensing was recognized in almost all normal sinus P waves for all cases examined using Holter ECG. Thus, chronotropic response during exercise by VDD pacemaker improved exercise tolerance, indicating that a VDD pacemaker might be useful for patients requiring physical activity.
Asunto(s)
Tolerancia al Ejercicio/fisiología , Marcapaso Artificial , Adulto , Anciano , Electrocardiografía Ambulatoria , Prueba de Esfuerzo/métodos , Prueba de Esfuerzo/estadística & datos numéricos , Femenino , Bloqueo Cardíaco/diagnóstico , Bloqueo Cardíaco/fisiopatología , Bloqueo Cardíaco/terapia , Humanos , Masculino , Persona de Mediana Edad , Marcapaso Artificial/estadística & datos numéricosRESUMEN
To evaluate the behavior of cardiac arrhythmias in dipper and nondipper hypertensive patients, 48-h ambulatory blood pressure monitoring, 24-h Holter electrocardiogram recording and echocardiographic studies were performed in 56 untreated outpatients with essential hypertension. These patients were divided into 2 groups according to the presence (dipper, n=33) or absence (nondipper, n=23) of reduction of both systolic and diastolic blood pressure during nighttime by an average of more than 10% of daytime blood pressure. Mean 48-h systolic and diastolic blood pressures did not differ between the 2 groups. Nondipper patients had a significantly larger left atrial dimension (31.9+/-3.8 vs 35.6+/-3.7 mm; p<0.01), left ventricular mass index (114+/-26 vs 136+/-36 g/m2; p<0.05), as well as a larger number of total supraventricular (16+/-19 vs 89+/-197 beats; p<0.05) and ventricular ectopic beats (7+/-14 vs 47+/-96 beats; p<0.05) during daytime as compared with dippers. In conclusion, nondipper hypertensive patients are likely to experience supraventricular and ventricular arrhythmias more frequently than dippers. A blunted nocturnal blood pressure fall may be involved in the appearance of cardiac arrhythmias in patients with essential hypertension.
Asunto(s)
Arritmias Cardíacas/etiología , Ritmo Circadiano , Hipertensión/complicaciones , Hipertrofia Ventricular Izquierda/etiología , Adulto , Anciano , Anciano de 80 o más Años , Arritmias Cardíacas/diagnóstico , Monitoreo Ambulatorio de la Presión Arterial , Complejos Cardíacos Prematuros/diagnóstico , Complejos Cardíacos Prematuros/etiología , Ecocardiografía , Electrocardiografía Ambulatoria , Femenino , Humanos , Hipertensión/diagnóstico , Hipertrofia Ventricular Izquierda/diagnóstico , Masculino , Persona de Mediana Edad , Volumen Sistólico , Complejos Prematuros Ventriculares/diagnóstico , Complejos Prematuros Ventriculares/etiologíaRESUMEN
The purpose of the study was to identify differences in the patterns of efficacy and duration of effects of imidapril administered at different times of the day (morning versus evening) in dipper and nondipper hypertensive patients. Twenty patients with untreated hypertension were classified into two groups: dippers (n = 9) and nondippers (n = 11). Imidapril (10 mg) was given at 07:00 or 18:00 for 4 weeks in a crossover fashion. Blood pressure (BP) and heart rate (HR) were monitored before and after morning and evening treatment every 30 min for 48h by ambulatory BP monitoring (ABPM). In dipper hypertension, the mean 48h BP was reduced with both doses. The decrease in the diurnal BP was stronger when the drug was administered in the evening than morning, but without significant difference. In nondipper hypertension, the systolic BP decreased at night with both doses, but the extent of the nocturnal reduction in systolic BP was greater after morning therapy. There were no significant differences in the decrease in BP during the day or night between the morning and evening administrations. When imidapril was administered in the morning, its serum concentration reached a maximum at 16:00, and when the drug was administered in the evening, it reached a maximum at 6:00. In dipper hypertension, the time taken for the blood concentration of imidapril to reach a maximum changed depending on its time of administration, and the time when the maximum antihypertensive effect of the drug appeared was different. In nondipper hypertension, decreases in the BP were confirmed at night regardless of the time of administration; this might be caused by angiotensin converting enzyme (ACE) inhibitors effectively blocking the BP from increasing by activating the parasympathetic nervous system. Therefore, when assessing the effectiveness of antihypertensive agents, factors such as the various patterns of BP before therapy and administration time must be considered.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Antihipertensivos/administración & dosificación , Antihipertensivos/uso terapéutico , Ritmo Circadiano/fisiología , Hipertensión/tratamiento farmacológico , Hipertensión/fisiopatología , Imidazoles/uso terapéutico , Imidazolidinas , Inhibidores de la Enzima Convertidora de Angiotensina/administración & dosificación , Inhibidores de la Enzima Convertidora de Angiotensina/farmacocinética , Antihipertensivos/farmacocinética , Presión Sanguínea/efectos de los fármacos , Epinefrina/sangre , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Frecuencia Cardíaca/fisiología , Humanos , Imidazoles/administración & dosificación , Imidazoles/farmacocinética , Masculino , Persona de Mediana Edad , Norepinefrina/sangre , Peptidil-Dipeptidasa A/sangre , Renina/sangreRESUMEN
The inhibitory effects of various endogenous and synthetic compounds on the nitration and oxidation of L-tyrosine by peroxynitrite were examined. Nitrating and oxidizing activities were monitored by the formation of 3-nitrotyrosine and dityrosine with a HPLC-UV-fluorescence detector system, respectively. Glutathione, serotonin and synthetic sulfur- and selenium-containing compounds inhibited both the nitration and oxidation reaction of L-tyrosine effectively. However, 5-methoxytryptamine, melatonin and alpha-lipoic acid only inhibited the nitration reaction, and enhanced the formation of an oxidation product. This is important evidence that there are different intermediates in the nitrating and oxidizing reactions of L-tyrosine by peroxynitrite. It was suggested that 5-methoxytryptamine, melatonin and alpha-lipoic acid reacted only with the nitrating intermediate of peroxynitrite and inhibited nitration of L-tyrosine. Actually, the DNA strand breakage, which is believed to be a typical reaction of hydroxyl radical-like species, caused by peroxynitrite was not effectively inhibited by 5-methoxytryptamine. 5-Methoxytryptamine, melatonin and alpha-lipoic acid were viewed as useful reagents for investigating the mechanisms of damage by peroxynitrite in vitro.
Asunto(s)
Depuradores de Radicales Libres/química , Nitratos/química , Ácido Tióctico/química , Triptaminas/química , Tirosina/química , Antioxidantes/síntesis química , Antioxidantes/química , Cromatografía Líquida de Alta Presión , Daño del ADN , Indicadores y Reactivos , Oxidación-Reducción , Plásmidos/química , Plásmidos/efectos de los fármacos , Espectrofotometría Ultravioleta , Detección de Spin , Tirosina/análogos & derivadosRESUMEN
Protein kinase C (PKC) has been known to play an important role in ischemic preconditioning (IP). This study was designed to examine whether the translocation of PKC is associated with the cardioprotective effects of IP in vivo on infarct size and ventricular arrhythmias in a rat model. Using anesthetized rats, heart rate, systolic blood pressure, infarct size and ventricular arrhythmias during 45 min of coronary occlusion were measured. PKC activity was assayed in both the cytosolic and cell membrane fraction. Brief 3-min periods ofischemia followed by 10 min ofreperfusion were used to precondition the myocardium. Calphostin C was used to inhibit PKC. Infarct size was significantly reduced by IP (68.1 (2.5)%, mean (S.E.) vs. 45.2 (3.4)%, p < 0.01). The reduction in infarct size by IP was abolished by pretreatment with calphostin C. The total number of ventricular premature complex (VPC) during 45 min of coronary occlusion was reduced by IP (1474 (169) beats/45 min vs. 256 (82) beats/45 min, p < 0.05). The reduction the total number of VPC induced by IP was abolished by the administration of calphostin C before the episode of brief ischemia. The same tendency was observed in the duration of ventricular tachycardia and the incidence of ventricular fibrillation. PKC activity in the cell membrane fraction transiently increased immediately after IP (100 vs. 142%, p < 0.01) and returned to baseline 15 min after IP. Pretreatment with calphostin C prevented the translocation of PKC. The translocation of PKC plays an important role in the cardioprotective effect of IP on infarct size and ventricular arrhythmias in anesthetized rats.
Asunto(s)
Arritmias Cardíacas/enzimología , Arritmias Cardíacas/prevención & control , Precondicionamiento Isquémico Miocárdico , Infarto del Miocardio/enzimología , Infarto del Miocardio/prevención & control , Proteína Quinasa C/metabolismo , Animales , Arritmias Cardíacas/fisiopatología , Transporte Biológico Activo , Membrana Celular/enzimología , Citosol/enzimología , Inhibidores Enzimáticos/farmacología , Hemodinámica , Masculino , Infarto del Miocardio/patología , Naftalenos/farmacología , Proteína Quinasa C/antagonistas & inhibidores , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Previous study has shown the antiarrhythmic effects of carvedilol on isolated rat hearts, but little is known about the mechanism of this protective action. This article examines the inhibitory effect of carvedilol against arrhythmias induced by reperfusion in anesthetized rats. In addition, the results are compared with those with propranolol, superoxide dismutase (SOD) plus catalase, and a combination of both in order to elucidate the mechanism of the protective actions. METHODS AND MATERIALS: Ninety percent of the rats in the control group showed lethal ventricular fibrillation (VF). Carvedilol at the doses of 0.03, 0.1, and 0.3 mg/kg significantly reduced the incidence of lethal VF to 0%, 0%, and 10%, respectively (P <.05). In contrast, propranolol at the doses of 0.3, 1.0, and 3.0 mg/kg and SOD (35,000 units/kg) plus catalase (400,000 units/kg) did not reduce the incidence of lethal VF (80%, 60%, 70%, and 70%, respectively). However, administration of a combination of propranolol (1.0 mg/kg) and SOD plus catalase completely inhibited the occurrence of lethal VF to 0% (P<.05). CONCLUSION: These results indicate that carvedilol has the inhibitory effect against reperfusion arrhythmias in rats and suggest that the mechanism of action of this compound is related to the combined effects of beta-blocking and antioxidant.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacología , Arritmias Cardíacas/tratamiento farmacológico , Carbazoles/farmacología , Daño por Reperfusión Miocárdica/fisiopatología , Propanolaminas/farmacología , Antagonistas Adrenérgicos beta/administración & dosificación , Anestesia General , Animales , Arritmias Cardíacas/etiología , Carbazoles/administración & dosificación , Carvedilol , Catalasa/metabolismo , Relación Dosis-Respuesta a Droga , Masculino , Propanolaminas/administración & dosificación , Propranolol/administración & dosificación , Propranolol/farmacología , Ratas , Ratas Sprague-Dawley , Superóxido Dismutasa/metabolismoRESUMEN
The antiarrhythmic effect of magnesium sulfate (Mg) as well as the hemodynamics were studied using the coronary ligation and reperfusion models in rats. In the study on coronary ligation arrhythmia, i.v. administration of Mg (0.6, 2, 6, 20 and 60 micromol) was conducted at 5 min after coronary ligation. Mg had an action to decrease the total number of premature ventricular contraction (PVC), the duration of ventricular tachycardia (VT), the frequency of VT and ventricular fibrillation (Vf) and the mortality ratio for 30 min after coronary ligation. In the 6-60 micromol groups, significant antiarrhythmic action (p < 0.01 vs. control) was attained. In the study on reperfusion arrhythmia, i.v. administration of Mg (20, 60 and 200 micromol) was conducted at 4 min after coronary ligation, and at 1 min after ligation, the coronary artery was reperfused. Mg had an action to decrease the frequency of Vf, the mortality ratio and the duration of VT and Vf and to extend the interval between the initiation of reperfusion and the occurrence of VT and Vf for 10 min after reperfusion. In the 200 micromol group, significant antiarrhythmic action (p < 0.05 vs. control) was attained. Administration of Mg decreased the heart rate and blood pressure. We concluded that Mg can control myocardial ischemia-induced and reperfusion-induced arrhythmia and that sudden cardiac death which occurs as a result of arrhythmia can be prevented.
Asunto(s)
Antiarrítmicos/farmacología , Arritmias Cardíacas/tratamiento farmacológico , Sulfato de Magnesio/farmacología , Anestesia , Animales , Arritmias Cardíacas/etiología , Calcio/sangre , Vasos Coronarios/cirugía , Hemodinámica/efectos de los fármacos , Ligadura , Magnesio/sangre , Masculino , Isquemia Miocárdica/complicaciones , Isquemia Miocárdica/tratamiento farmacológico , Reperfusión Miocárdica/efectos adversos , Potasio/sangre , Ratas , Ratas Sprague-DawleyRESUMEN
OBJECTIVE: To investigate whether autonomic nervous activity is involved in the recurrence of spontaneous coronary spasm in variant angina. DESIGN: Retrospective analysis. SETTING: Cardiology department of a university hospital. PATIENTS: 18 patients with variant angina were divided into single attack group (SA; nine patients) and multiple attack group (MA; nine patients) according to the frequency of ischaemic episodes with ST segment elevation during 24 hour Holter monitoring. METHODS: Heart rate variability indices were calculated using MemCalc method, which is a combination of the maximum entropy method for spectral analysis and the non-linear least squares method for fitting analysis, at 30 second intervals for 30 second periods, from 40 minutes before the attack to 30 minutes after the attack. High frequency (HF; 0.04-0.15 Hz) was defined as a marker of parasympathetic activity, and the ratio of low frequency (LF; 0.15-0.40 Hz) to high frequency (LF/HF) as an indicator of sympathetic activity. The averaged value during the 40 to 30 minute period before an attack was defined as the baseline. RESULTS: Compared with baseline, the HF component decreased in both groups at two minutes before the attack (p < 0.01), and the LF/HF ratio decreased at three minutes before the attack (p < 0.01). The baseline LF/HF was lower in the MA group than in the SA group (p < 0. 01). CONCLUSIONS: A reduction of sympathetic activity may play a key role in determining the recurrence of transient ischaemic events caused by spontaneous coronary spasm in patients with variant angina.
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Angina Pectoris Variable/fisiopatología , Sistema Nervioso Autónomo/fisiopatología , Anciano , Análisis de Varianza , Electrocardiografía Ambulatoria , Femenino , Frecuencia Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Recurrencia , Estudios Retrospectivos , Procesamiento de Señales Asistido por ComputadorRESUMEN
3SB, a mouse thymoma cell line, is one of the most radio-sensitive cells (D0 = 0.3 Gy), and its rapid apoptosis (4 h after 5 Gy irradiation, 90% apoptosis) seems to play a decisive role in enhancing the radiosensitivity. To understand the molecular mechanisms underlying extremely high radiosensitivity and rapid apoptosis, we attempted to isolate X-ray-resistant (XR) variants from 3SBH5, a stable subclone of 3SB, by repeating exposure of the cells to 2-5 Gy X-rays. Four independent stable XR variants, R111, R223, R316 and R429, were isolated by the repeated irradiation protocols. All XR cells possessed about 3 times higher D10 values than that of their parental 3SBH5. They were also resistant to apoptosis; only 10% cells underwent apoptosis 4 h after 5 Gy irradiation. The p53 protein was induced in all the cell lines after 5 Gy X-irradiation. These variants showed a cross resistance to a chemical reagent daunorubicin (DNR) that is known to be involved in the ceramide-mediated apoptosis. DNR, as well as C2-ceramide (5 muM) induced apoptosis in parental 3SBH5 cell, but not in two XR variants, R233 and R316 cells. Present result suggests that the induction of X-ray resistance by repeated X-irradiation might be achieved, at least partly, by the enhanced resistance to the ceramide-mediated apoptosis.
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Apoptosis/genética , Apoptosis/efectos de la radiación , Tolerancia a Radiación/genética , Timoma/genética , Timoma/radioterapia , Neoplasias del Timo/genética , Neoplasias del Timo/radioterapia , Animales , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Daunorrubicina/farmacología , Resistencia a Medicamentos/genética , Variación Genética , Metilmetanosulfonato/farmacología , Ratones , Mitomicina/farmacología , Mutágenos/farmacología , Esfingosina/análogos & derivados , Esfingosina/metabolismo , Timoma/tratamiento farmacológico , Timoma/patología , Neoplasias del Timo/tratamiento farmacológico , Neoplasias del Timo/patología , Células Tumorales Cultivadas , Proteína p53 Supresora de Tumor/biosíntesisRESUMEN
The relation between blood pressure (BP) variation and hypertensive organ damage is controversial. The reproducibility of the circadian variation pattern acceptable as the standard for discriminating between "dippers" and "nondippers" has not yet been evaluated. We evaluated the reproducibility of "dipper" and "nondipper" patterns in essential hypertensives by monitoring BP for 48 h. Noninvasive ambulatory BP and heart rate (HR) monitoring for 48 h every 30 min were performed in 253 untreated patients with mild-to-moderate essential hypertension. Mean daytime (awake) and nighttime (sleeping) systolic BP, diastolic BP, and HR values were analyzed by reviewing the patients' diaries. Patients were divided into two groups by presence (dippers) and absence (nondippers) of a reduction of both systolic and diastolic BP during the night of > 10% of the daytime pressure. A subject who was a dipper on day 1 remained a dipper on day 2 in 41% (n = 103, DD group) and changed to nondipper in 16% (n = 41, DN group). A subject who was a nondipper on day 1 remained a nondipper on day 2 in 30% (n = 75, NN group) and changed to a dipper in 13% (n = 34, ND group). Our findings indicate that there is a high risk of false-positive or false-negative results when 24-h recordings are used to identify dipper and nondipper profiles.
Asunto(s)
Presión Sanguínea/fisiología , Ritmo Circadiano/fisiología , Hipertensión/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Monitoreo Ambulatorio de la Presión Arterial , Diástole , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , SístoleRESUMEN
The aim of this study was to identify the relationship of QT dispersion on 12-lead electrocardiograms and left ventricular mass index on echocardiograms associated with the circadian rhythm of blood pressure (BP). Heart rate and BP were monitored every 30 min for 48 h in 62 patients with essential hypertension using an ambulatory BP monitoring device. The patients were divided into four groups according to gender and circadian BP pattern (nocturnal BP dipper or nondipper). The patients were classified as dippers if their daytime BP decreased by at least 10% during the night and all the other subjects were classified as nondippers. Age, body mass index, and 48-h mean BP were similar among the four groups. During the night-rest period, the systolic and diastolic BP were significantly decreased in dipper-type hypertensives. The maximum QTc interval and QTc dispersion were longer in nondippers than in dippers. Left ventricular mass index (LVMI) had a tendency to increase in nondippers. The nocturnal reduction of BP significantly correlated with QTc dispersion and LVMI. The QTc dispersion significantly correlated with LVMI and interventricular septum thickness.
Asunto(s)
Electrocardiografía , Hipertensión/fisiopatología , Adulto , Anciano , Presión Sanguínea/fisiología , Ritmo Circadiano/fisiología , Ecocardiografía , Femenino , Tabiques Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos , Humanos , Hipertensión/diagnóstico por imagen , Masculino , Persona de Mediana EdadRESUMEN
We evaluated the circadian variation and exercise stress response patterns of blood pressure (BP) in elderly patients with essential hypertension. Ambulatory BP monitoring for 48 hours every 30 minutes, and treadmill exercise test using a Bruce protocol at PM 3 to 5 were performed in 49 untreated patients with hypertension. Mean daytime (awake), and night-time (sleeping) systolic BP (SBP) and diastolic BP (DBP) values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP and DBP were calculated according to the following formula. NRR (%) = [(daytime mean-nighttime mean)/daytime mean] x 100. The patients were divided into two groups according to the presence (dipper, n = 25) or absence (non-dipper, n = 24) of a reduction in both SBP and DBP during the night by an average of more than 10% of the daytime BP. Mean values of SBP and DBP measured over 48 hours in the dipper and non-dipper groups were similar. Responses of SBP to dynamic exercise at 2 to 5 minutes in the non-dipper group were significantly smaller than those in the dipper group (p < 0.05). Non-dipper patients with hypertension responded to dynamic exercise stress with smaller increases in SBP than did those in the dipper group. The differences in BP responses to exercise may affect the circadian blood pressure profile in dipper and non-dipper elderly patients with essential hypertension.
Asunto(s)
Presión Sanguínea , Ritmo Circadiano , Ejercicio Físico/fisiología , Hipertensión/fisiopatología , Anciano , Monitoreo Ambulatorio de la Presión Arterial , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
The aim of this study was to assess the effect of menopause on circadian profile of blood pressure (BP) and heart rate (HR) in the normotensive pre- and postmenopausal women. Systolic BP (SBP), diagnostic BP (DBP) and HR were monitored every 30 min for 48 hrs using noninvasive ambulatory BP monitoring in 24 premenopausal and 40 postmenopausal women. Mean 48-hours, daytime (awake), and nighttime (sleeping) SBP, DBP and HR values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP, DBP and HR were calculated according to the following formula. NRR (%9 = [(daytime mean-nighttime mean)/daytime mean] x 100. The study subjects were then divided into two groups according to the presence (dipper) or absence (nondipper) of a significant reduction in nocturnal BP (> 10%). Mean SBP, DBP and HR measured over 48 hours were similar between the premenopausal and the postmenopausal group. The NRR of DBP and HR in the postmenopausal group were significantly smaller than those in the premenopausal group (17.1 +/- 6.0% vs. 13.5 +/- 7.0%, 241.1 +/- 6.0% vs. 19.8 +/- 9.0%: p < 0.05). There tended to be higher prevalence of nondipper in the postmenopausal (37%) than in the premenopausal group (29%).
Asunto(s)
Presión Sanguínea , Ritmo Circadiano , Frecuencia Cardíaca , Posmenopausia/fisiología , Premenopausia/fisiología , Adulto , Femenino , Humanos , Persona de Mediana EdadRESUMEN
Nine mutants isolated from CHO.K1 cells with increased sensitivity to the lethal effect of plumbagin (PG), a powerful superoxide generator, were classified into five groups, A-E, according to their sensitivity to PG and methyl viologen (MV). Two mutants of group B (Pa13 and Pb4) were sensitive to both drugs, and two mutants of group C (Pa14 and Pa15) were moderately sensitive to PG and extremely sensitive to MV. To mitomycin C (MMC) these mutants showed cross-sensitivity; especially Pa13 and Pb4 (group B) were highly sensitive to MMC. Genetic complementation analyses of these four mutants were carried out using MV sensitivity. Sensitivity group B was divided into two complementation group, I and II. Pa14 and Pa15 belonged to the same complementation group III. These four mutants were also classified into three complementation groups for MMC sensitivity. Because Pa13 and Pb4 were also sensitive to cis-diamminedichloroplatinum(II), they may have a defect in the repair of DNA crosslinks induced by these agents. A complementation group IV (Pa2 and Pa8) was also suggested based on the studies of MMC sensitivity.