Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Eur J Clin Pharmacol ; 54(3): 209-14, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9681661

RESUMO

OBJECTIVE: Patients with heart failure have abnormal neurohormonal regulation during orthostatic stress, and abnormal arterial baroreflex function. This study investigated the effects of alacepril, a new angiotensin-converting enzyme inhibitor with sulfhydryls, on changes in neurohormonal factors during tilt and on the arterial baroreflex control of heart rate. METHODS: Plasma concentrations of noradrenaline, adrenaline, renin activity, angiotensin II, and atrial natriuretic peptide were measured at supine rest and after 30 degrees head-up tilt with measurements of central venous pressure and cardiac dimensions in seven patients with congestive heart failure (65 years, ejection fraction = 34%). Arterial baroreflex control of heart rate was assessed by phenylephrine bolus. The arterial baroreflex test was re-examined 3 h after oral alacepril (37.5 mg). The tilt and arterial baroreflex tests were repeated 12 weeks after alacepril treatment (50 mg x day(-1)). RESULTS: Heart rate, blood pressure, and neurohormonal factors did not differ before and after chronic alacepril, except for a trend toward an increase in renin activity (2.0 vs 4.9 ng x ml(-1) x h(-1)). Head-up tilt decreased central venous pressure (-2.5 mmHg) with a decrease in cardiac dimensions in the pre-alacepril phase. These changes were accompanied by increases in noradrenaline, adrenaline, and angiotensin II and a decrease in atrial natriuretic peptide. After chronic alacepril, the increase in noradrenaline during head-up tilt tended to be smaller (84 vs 30 pg x ml(-1)), with similar changes in central venous pressure (-3.4 mmHg) and cardiac dimensions. Both acute (3.6 vs 4.8 ms mmHg(-1)) and chronic (3.6 vs 6.7 ms mmHg(-1)) alacepril treatment was associated with a trend towards an increase in the arterial baroreflex control of heart rate. CONCLUSION: These results suggest that treatment with alacepril may cause a reduction of sympathetic activation during orthostatic stress and may enhance arterial baroreflex function in patients with mild to moderate heart failure.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Barorreflexo/efeitos dos fármacos , Captopril/análogos & derivados , Insuficiência Cardíaca/tratamento farmacológico , Neuropeptídeos/efeitos dos fármacos , Neurotransmissores/sangue , Idoso , Angiotensina II/sangue , Angiotensina II/efeitos dos fármacos , Inibidores da Enzima Conversora de Angiotensina/administração & dosagem , Artérias/efeitos dos fármacos , Artérias/fisiologia , Fator Natriurético Atrial/sangue , Fator Natriurético Atrial/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Captopril/administração & dosagem , Captopril/uso terapêutico , Relação Dose-Resposta a Droga , Epinefrina/sangue , Feminino , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/fisiopatologia , Frequência Cardíaca/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Neuropeptídeos/sangue , Norepinefrina/sangue , Renina/sangue , Renina/efeitos dos fármacos , Teste da Mesa Inclinada , Função Ventricular Esquerda/efeitos dos fármacos
2.
Gen Pharmacol ; 31(1): 93-9, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9595286

RESUMO

1. Treatment with spironolactone is reported to be useful when combined with loop diuretics and an angiotensin-converting enzyme (ACE) inhibitor in severe congestive heart failure (CHF). However, the effects of the addition of spironolactone on exercise capacity and neurohormonal variables have not been demonstrated. This study determined the effects of additive spironolactone on exercise capacity and neurohormonal factors in patients with mild CHF. 2. Oxygen uptake (VO2), plasma norepinephrine (NE), renin activity (PRA), angiotensin II (AII), aldosterone (ALD), and atrial natriuretic peptide (ANP) were measured at rest and after peak exercise in nine patients with CHF (six idiopathic and three ischemic cardiomyopathy; New York Heart Association (NYHA) classes II and III) who were already taking furosemide (mean 29 +/- 5 mg/day) and enalapril (mean 4.7 +/- 0.8 mg/day). Studies were repeated after 16 weeks of treatment with additive single daily dose of 25 mg of spironolactone. In four of nine patients, the exercise test was repeated after a 4-weeks washout of spironolactone. 3. Treatment with spironolactone caused natriuresis, decreased cardiothoracic ratio in chest X-ray (before vs. after treatment: 53.7 +/- 1.2 vs. 50.7 +/- 1.4%, P < 0.01), and improved NYHA functional class. Peak VO2 (17.1 +/- 1.6 vs. 17.5 +/- 2.2 ml/min/kg, NS) and heart rate and blood pressure responses to exercise were not altered. Resting NE (215 +/- 41 vs. 492 +/- 85 pg/ml, P < 0.01) and resting PRA (8.2 +/- 2.3 vs. 16.2 +/- 4.1 ng/ml/hr, P < 0.01) as well as peak NE (1618 +/- 313 vs. 2712 +/- 374 pg/ml, P < 0.01) and peak PRA (12.8 +/- 3.2 vs. 28.1 +/- 11.8 ng/ml/hr, P = 0.17) were augmented after additive spironolactone. ALD and AII were insignificantly increased, and ANP was insignificantly decreased at peak exercise after spironolactone treatment. Spironolactone washout was associated with a trend of the neurohormones to return toward pretreatment values. 4. In conclusion, chronic additive treatment with spironolactone was associated with neurohormonal activation both at rest and during exercise without changing the exercise capacity of patients with mild CHF who were already on loop diuretics and ACE inhibitor therapy.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Diuréticos/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Sistemas Neurossecretores/efeitos dos fármacos , Espironolactona/uso terapêutico , Adulto , Idoso , Ecocardiografia , Eletrólitos/urina , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Ventilação Pulmonar
3.
Clin Exp Pharmacol Physiol ; 25(12): 1018-23, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9888000

RESUMO

1. There is controversy regarding plasma catecholamine levels in patients with hypertrophic cardiomyopathy (HCM) and few data exist on serial plasma catecholamine measurements during exercise. The present study determined whether cardiovascular and plasma catecholamine responses to exercise were altered in patients with HCM. 2. Plasma noradrenaline (NA) and adrenaline were measured at rest, at the end of each stage during exercise and immediately and 5 min after submaximal treadmill exercise in 15 patients with non-obstructive HCM (13 males, two females; mean (+/- SEM) age 54 +/- 3 years) and in 15 age- and sex-matched controls. The ratio of the increment in heart rate (HR) divided by the increment in plasma NA during exercise (delta HR/delta NA) was used as an index of chronotropic sympathetic responsiveness to exercise. 3. Exercise duration was shorter (11.2 +/- 0.6 vs 8.7 +/- 0.6 min for control vs HCM, respectively; P < 0.01) and diastolic blood pressure was significantly higher at stages I and II of modified Bruce protocol HCM. 4. Resting plasma NA levels (149 +/- 17 vs 167 +/- 28 pg/mL for control vs HCM, respectively; NS) were not different, but plasma NA levels at stages I and II were significantly higher in HCM than in controls (243 +/- 26 vs 399 +/- 69 pg/mL (P < 0.05) and 308 +/- 30 vs 548 +/- 110 pg/mL (P < 0.05), respectively). 5. Peak plasma NA levels were not significantly higher in HCM than in controls (578 +/- 59 vs 918 +/- 184 pg/mL, respectively; NS). 6. The ratio delta HR/delta NA was significantly lower in HCM compared with control at stages I and II (0.49 +/- 0.10 vs 0.21 +/- 0.05 (P < 0.05) and 0.38 +/- 0.06 vs 0.20 +/- 0.05 (P < 0.05), respectively). There were no differences in plasma adrenaline responses during exercise between the two groups. 7. Patients with HCM had augmented plasma NA levels during submaximal exercise with a higher diastolic blood pressure response. Chronotropic sympathetic responsiveness was impaired during the early stages of exercise in patients with HCM.


Assuntos
Pressão Sanguínea/fisiologia , Cardiomiopatia Hipertrófica/sangue , Frequência Cardíaca/fisiologia , Norepinefrina/sangue , Adulto , Cardiomiopatia Hipertrófica/fisiopatologia , Epinefrina/sangue , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
4.
Stroke ; 28(7): 1461-3, 1997 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9227701

RESUMO

BACKGROUND: We report here a rare case of repeated syncopal episodes associated with smoking and findings of 99mTc-hexamethylpropyleneamine oxime (HMPAO) brain single-photon emission CT (SPECT) imaging. CASE DESCRIPTION: A 77-year-old man had four syncopal episodes during a half-month period. All four occurred when he stood up and walked immediately after smoking a cigarette, and syncope did not occur after cessation of smoking. Although upright testing revealed orthostatic hypotension, the patient did not complain of fainting on standing alone. Compared with brain SPECT in the supine position, perfusion was decreased in the posterior circulation structures after the subject smoked a cigarette or chewed nicotine gum. CONCLUSIONS: The combination of cerebral vasoconstriction due to smoking and orthostatic hypotension probably decreased cerebral blood flow in this patient, resulting in syncope.


Assuntos
Fumar/efeitos adversos , Síncope/diagnóstico por imagem , Síncope/etiologia , Idoso , Circulação Cerebrovascular/efeitos dos fármacos , Humanos , Masculino , Compostos de Organotecnécio , Oximas , Tecnécio Tc 99m Exametazima , Tomografia Computadorizada de Emissão de Fóton Único/métodos
5.
Cardiology ; 88(3): 238-45, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9129844

RESUMO

Neurohormonal responses to exercise have not been studied fully in patients with essential hypertension (HT). This study determined if neurohormonal responses to exercise are altered between three subgroups of HT categorized by basal plasma renin activity (PRA). Plasma norepinephrine, epinephrine, atrial natriuretic peptide (ANP), PRA, angiotensin II (AII), and aldosterone were measured at rest and after submaximal treadmill exercise in 39 patients with essential HT (WHO classes I-II) and 13 controls. Patients with HT were divided into three subgroups based on the PRA level [low-renin (< 0.5) HT (n = 14), normal-renin (0.5-2.0) HT (n = 13), and high-renin (> 2.0) HT (n = 12)]. Patients with HT had higher blood pressure during exercise compared to controls, but blood pressure responses were similar among low-, normal-, and high-renin HT. Neurohormonal factors were comparable between all hypertensives and controls, except for higher plasma AII at rest in patients with HT. When neurohormones were compared among three subgroups of HT, plasma norepinephrine and epinephrine responses were similar. Patients with high-renin HT had higher PRA and AII, and lower ANP levels at rest and after exercise. In all hypertensives, negative correlations were observed between resting PRA and resting ANP (r = -0.41, p < 0.01), as well as peak PRA and peak ANP (r = -0.33, p < 0.05). Thus, neurohormonal responses to exercise varied with similar cardiac responses among subgroups of essential HT stratified according to renin levels. Patients with high-renin HT had augmented renin-angiotensin system activity with a decrease in ANP levels both at rest and after exercise. A reciprocal relationship between renin-angiotensin system activity and ANP was observed both at rest and after exercise in HT.


Assuntos
Fator Natriurético Atrial/sangue , Catecolaminas/sangue , Exercício Físico/fisiologia , Hipertensão/sangue , Sistema Renina-Angiotensina/fisiologia , Adulto , Idoso , Aldosterona/sangue , Angiotensina II/sangue , Pressão Sanguínea , Cromatografia Líquida de Alta Pressão , Ecocardiografia , Feminino , Frequência Cardíaca , Humanos , Hipertensão/diagnóstico por imagem , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Renina/sangue , Descanso
6.
Cardiology ; 88(1): 6-13, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-8960618

RESUMO

The effects of enalapril on exercise capacity and neurohumoral factors during exercise were evaluated in 10 patients with heart failure. Echocardiograms and exercise testing with expired gas analysis were performed before and after enalapril. Blood samples were obtained before and after exercise. Both ejection fraction and percent fractional shortening increased with enalapril (p < 0.05). The anaerobic threshold and peak VO2 did not change with enalapril. Epinephrine and norepinephrine levels at peak exercise decreased with enalapril (p < 0.1). Plasma renin both at rest and at peak exercise increased with enalapril (p < 0.1). Angiotensin II was lower after enalapril both at rest and at peak exercise (p < 0.1 and p < 0.05, respectively). Aldosterone was lower after enalapril both at rest and at peak exercise (p < 0.05). Atrial natriuretic peptide (ANP) was lower after enalapril both at rest and at peak exercise. There was no significant correlations between peak VO2 and changes in neurohumoral factors before and after enalapril during exercise. In conclusion, neurohumoral changes with enalapril occurred during exercise even if exercise capacity did not improve. Moreover, the improvement of cardiac function at rest and neurohumoral factors with enalapril did not lead to a change of exercise capacity.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/administração & dosagem , Enalapril/administração & dosagem , Tolerância ao Exercício/efeitos dos fármacos , Exercício Físico/fisiologia , Insuficiência Cardíaca/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Limiar Anaeróbio/efeitos dos fármacos , Gasometria , Doença Crônica , Relação Dose-Resposta a Droga , Ecocardiografia , Eletrocardiografia , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Neurotransmissores/sangue , Radiografia Torácica , Radioimunoensaio
7.
Jpn Circ J ; 60(12): 909-16, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8996680

RESUMO

Neurohormonal activation is present and neurohormonal responses to dynamic exercise are altered in patients with congestive heart failure (CHF). The aim of this study was to determine if the responses of atrial natriuretic peptide (ANP) normalized for peak oxygen consumption (peak VO2) to exercise are augmented in patients with CHF. Ventilatory and ANP responses were assessed in 28 patients with CHF (NYHA classes II: 16, III: 12), 17 patients in NYHA class I, and 14 normal subjects during symptom-limited cardiopulmonary exercise testing. Plasma ANP was measured at rest and immediately after peak exercise. The increase in ANP was divided by peak VO2 and this ratio [ANP-Exercise Ratio: (peak ANP-rest ANP)/peak VO2] was compared among the 3 groups. Peak VO2 (Normal, NYHA I, CHF: 29.9 +/- 1.7, 24.0 +/- 1.3, 17.4 +/- 0.8 ml/min per kg), anaerobic threshold and peak work rate were lower in patients with CHF. The resting ANP level was significantly higher in patients with CHF (Normal, NYHA I, CHF: 35.4 +/- 4.6, 42.9 +/- 5.8, 80.8 +/- 12.9 pg/ml). The ANP level increased during exercise in all 3 groups, and patients with CHF had a significantly higher ANP level than normal subjects and NYHA class I patients (Normal, NYHA I, CHF: 65.3 +/- 10.7, 75.9 +/- 14.4, 141.6 +/- 20.1 pg/ml). The ANP-Exercise Ratio in patients with CHF was significantly higher than those in normal subjects and NYHA class I patients (Normal, NYHA I, CHF: 0.96 +/- 0.26, 1.32 +/- 0.38, 3.59 +/- 0.72). These data suggest that patients with CHF but not those in NYHA class I have an augmented ANP response, as reflected by both absolute ANP levels and by the exercise ratio, which was normalized by the peak exercise level.


Assuntos
Fator Natriurético Atrial/sangue , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/fisiopatologia , Esforço Físico/fisiologia , Pressão Sanguínea/fisiologia , Ventrículos Cerebrais/metabolismo , Feminino , Cardiopatias/etiologia , Cardiopatias/fisiopatologia , Frequência Cardíaca/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Peptídeo Natriurético Encefálico , Proteínas do Tecido Nervoso/sangue , Proteínas do Tecido Nervoso/metabolismo , Consumo de Oxigênio/fisiologia , Respiração/fisiologia
8.
Am J Med Sci ; 312(3): 110-7, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8783676

RESUMO

The aim of this study was to determine the responses of plasma catecholamines, renin-angiotensin-aldosterone (RAA) activity, and plasma atrial natriuretic peptide (ANP) to exercise in patients with congestive heart failure (CHF). Cardiac and neurohormonal responses were assessed during submaximal treadmill exercise testing in 23 patients with CHF (New York Heart Association classes I-III) and 13 control subjects (without CHF). Plasma norepinephrine, epinephrine, renin activity (PRA), angiotensin II (ATII), aldosterone, and ANP were measured at rest and immediately after exercise. Exercise duration was shorter in patients with CHF (control, 10.4 +/- 0.9 minute; CHF, 6.2 +/- 0.7 minute; P < 0.01). Heart rate and blood pressure responses were similar except for the smaller peak heart rate (control, 145 +/- 5 beats per minute; CHF, 129 +/- 4 beats per minute; P < 0.05) and higher systolic blood pressure at recovery stage (control, 122 +/- 4 mm Hg; CHF, 142 +/- 4 mm Hg; P < 0.01) in patients with CHF. At rest, plasma norepinephrine levels were insignificantly higher in patients with CHF (control, 110 +/- 10 pg/mL; CHF, 170 +/- 26 pg/mL; P = 0.09), and ANP levels (control, 40 +/- 5 pg/mL; CHF, 94 +/- 17 pg/mL; P < 0.05) and PRA levels (control, 0.77 +/- 0.11 ng/mL/hr; CHF, 4.33 +/- 1.25 ng/mL/hr; P < 0.05) were significantly higher. There were no differences in peak norepinephrine, epinephrine, or ANP between the two groups. Angiotensin II and aldosterone levels were similar between the two groups, although, in patients with CHF, there was a trend toward higher levels of ATII while at rest (control, 12.4 +/- 1.4 pg/mL; CHF, 20.3 +/- 3.3 pg/mL; P = 0.08) and at peak (control, 20.5 +/- 1.8 pg/mL; CHF, 41.0 +/- 9.4 pg/mL; P = 0.10). Peak values of PRA, ATII, and aldosterone positively correlated with respective resting values of PRA (r = 0.88 ng/mL/hr, P < 0.01), ATII (r = 0.63 pg/mL, P < 0.01), and aldosterone (r = 0.99, P < 0.01). Peak norepinephrine and peak ANP also positively correlated with respective resting values of norepinephrine (r = 0.58 pg/mL, P < 0.05) and ANP (r = 0.94, P < 0.01). Analysis of these results showed that patients with CHF had significantly higher levels of PRA and ANP at rest, and a trend toward augmentation in RAA system activity during exercise with less exercise workload. Basal level of neurohormones seemed to be an important determinant for the degree of exercise-induced neurohormonal activation in patients with CHF.


Assuntos
Fator Natriurético Atrial/sangue , Catecolaminas/sangue , Exercício Físico/fisiologia , Insuficiência Cardíaca/metabolismo , Sistema Renina-Angiotensina/fisiologia , Pressão Sanguínea , Teste de Esforço , Feminino , Insuficiência Cardíaca/classificação , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Descanso/fisiologia , Estatística como Assunto
9.
Jpn Circ J ; 60(9): 641-51, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8902582

RESUMO

We studied the relation between exercise-induced U-wave changes and the site of a reversible defect in tomographic 201Tl myocardial imaging. Coronary artery disease and control groups consisted of 116 and 42 patients, respectively. In the anteroapical-ischemia group (n = 37), the sensitivity of U-wave inversion in the anterior precordial leads for ischemia was 62% (23/37) and that of prominent U-waves without an increase in the height of the T-wave in the inferior limb leads was 57% (21/37). In this group, 18 patients (49%) met both criteria (18 [78%] of 23 patients with the former; 18 [86%] of 21 patients with the latter). In the posterior-ischemia group (n = 59), the sensitivity of prominent U-waves with a decrease in the height of the T-wave in the anterior precordial leads for ischemia was 63% (37/59) and that of U-wave inversion in the inferior limb leads was 20% (12/59). In this group, 12 patients (20%) met both criteria (12 [32%] of 37 patients with the former; all 12 patients with the latter). The specificity of U-wave criteria was 100%. In the anteroapical and posterior ischemia group (n = 20), the sensitivity of U-wave criteria for anteroapical and posterior ischemia was 85% (17/20) and 40% (8/20), respectively. In conclusion, U-wave criteria are not only specific but also sensitive for myocardial ischemia determined by 201Tl imaging.


Assuntos
Doença das Coronárias/fisiopatologia , Eletrofisiologia , Exercício Físico , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Radioisótopos de Tálio
10.
J Card Fail ; 2(2): 103-10, 1996 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8798111

RESUMO

BACKGROUND: Neurohormonal activation is present and neurohormonal responses to dynamic exercise are altered in congestive heart failure (CHF). Responses of plasma norepinephrine in various degrees of heart failure have been investigated, but the responses of the renin-angiotensin-aldosterone system have not been studied in relation to the severity of CHF. The aim of this study was to determine if the responses of the renin-angiotensin-aldosterone system to exercise are augmented according to the severity of CHF. METHODS AND RESULTS: Ventilatory and neurohormonal responses were assessed in 38 patients with CHF (New York Heart Association class: I, 13 patients; II, 14 patients; III, 11 patients) and 11 normal subjects during symptom-limited cardiopulmonary exercise testing. Plasma norepinephrine, renin activity, angiotensin II, and aldosterone were measured at rest and at peak exercise. The increments in neurohormones were divided by peak oxygen consumption, and these ratios (norepinephrine exercise ratio, plasma renin activity-exercise ratio, angiotensin II-exercise ratio, aldosterone-exercise ratio) were compared among groups. Peak oxygen consumption and anaerobic threshold decreased progressively with the severity of CHF. Neurohormonal profiles at rest showed that plasma norepinephrine levels were significantly higher, and the renin-angiotensin-aldosterone system was augmented only in patients with class III CHF. Neurohormones increased during exercise both in patients with CHF and in normal subjects, but patients with class III CHF had significantly higher plasma renin activity (10.11 +/- 2.32 ng/mL/h), angiotensin II (73.9 +/- 14.2 pg/mL), and aldosterone (265.2 +/- 61.1 pg/mL) than did normal subjects. Plasma renin activity-exercise ratio, angiotensin II-exercise ratio, and aldosterone-exercise ratio in patients with class III CHF were significantly higher compared to normal subjects. This augmentation of the renin-angiotensin-aldosterone system was not observed in class I or II patients. Peak plasma norepinephrine levels were not different among normal subjects and subgroups of CHF patients, but the norepinephrine-exercise ratio was significantly higher in classes II and III CHF compared to normal subjects. CONCLUSIONS: These data suggest that neurohormonal excitation during exercise increases along with the severity of CHF when normalized for peak exercise level.


Assuntos
Exercício Físico/fisiologia , Insuficiência Cardíaca/fisiopatologia , Norepinefrina/sangue , Sistema Renina-Angiotensina/fisiologia , Sistema Nervoso Simpático/metabolismo , Aldosterona/sangue , Angiotensina II/sangue , Feminino , Insuficiência Cardíaca/sangue , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio/fisiologia , Ventilação Pulmonar , Renina/sangue
11.
Heart ; 75(4): 343-8, 1996 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8705758

RESUMO

OBJECTIVE: To assess energy depletion in skeletal muscle in patients with congestive heart failure by measuring blood purine metabolites during exercise and, at the same time, determine the implications of the ammonia response to exercise in these patients. SETTING: Tottori University Hospital, Yonago, Japan. PATIENTS: 49 heart failure patients (New York Heart Association (NYHA) grades I-III) and 16 normal subjects. MAIN OUTCOME MEASURES: Blood lactate, ammonia, and hypoxanthine levels were measured during exercise with expired gas analysis. RESULTS: In normal exercising subjects as well as in each heart failure subgroup, the ammonia threshold was significantly higher than both the lactate threshold [control: 21.8 (SD 5.3) v 17.4 (3.3) ml/kg/min; NYHA class I: 18.9 (3.8) v 15.5 (2.6); class II: 14.8 (2.5) v 12.7 (2.4); class III: 13.5 (2.6) v 11.8 (2.5)] and the ventilatory threshold (P < 0.01). The difference between the ammonia and lactate thresholds was noted in all normal subjects and in all heart failure patients. The ammonia threshold, however, was significantly lower in heart failure patients than in normal subjects and it decreased with increasing NYHA class (P < 0.01). Maximum ammonia levels were lower in the heart failure group and decreased further with higher NYHA classifications [control: 198 (52) mg/dl; NYHA class I: 170 (74); class II: 134 (58); class III: 72 (15); P < 0.01]. There were significant correlations between maximum ammonia values and maximum lactate, oxygen consumption, and hypoxanthine levels (r = 0.74, 0.48, and 0.87, respectively; P < 0.001). CONCLUSIONS: The ammonia threshold may reflect the onset of ATP depletion in exercising skeletal muscles, as opposed to the onset of anaerobic respiration. It seems therefore that energy depletion in skeletal muscles during exercise occurs after attaining the anaerobic threshold. Both aerobic and anaerobic capacities of skeletal muscle are reduced in patients with congestive heart failure.


Assuntos
Amônia/sangue , Exercício Físico/fisiologia , Insuficiência Cardíaca/sangue , Trifosfato de Adenosina/metabolismo , Teste de Esforço , Feminino , Insuficiência Cardíaca/metabolismo , Humanos , Hipoxantina , Hipoxantinas/sangue , Lactatos/sangue , Ácido Láctico , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Consumo de Oxigênio
12.
Jpn Circ J ; 59(11): 725-35, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8747762

RESUMO

We studied the causes of exercise-induced ST-segment elevation. Group I consisted of 15 patients with anterior myocardial infarction in the absence of a coronary artery luminal narrowing of 75% or more. Group II consisted of 36 patients with predominantly exertional angina and a luminal narrowing of 90% or more in the left anterior descending coronary artery in the absence of previous myocardial infarction. In group I, exercise-induced ST-segment elevation occurred frequently during treadmill exercise (15/15, 100%). None of the patients showed 201Tl redistribution. The standard deviation of the phase in radionuclide ventriculography increased during bicycle exercise. Of group II patients, only those with 99% narrowing and poor collaterals showed exercise-induced ST-segment elevation (13/14, 93%), whereas none of those with complete occlusion or 99% narrowing and good collaterals, or 90% narrowing showed ST-segment elevation. In group II, patients with exercise-induced ST-segment elevation showed lower 201Tl uptake during exercise and washout in the territory of the diseased vessel than those without exercise-induced ST-segment elevation. In conclusion, wall motion abnormalities may cause exercise-induced ST-segment elevation independently of myocardial ischemia. In patients with predominantly exertional angina, exercise-induced ST-segment elevation may be a marker for 99% narrowing with poor collaterals and severe myocardial ischemia.


Assuntos
Doença das Coronárias/diagnóstico , Eletrocardiografia , Contração Miocárdica , Função Ventricular Esquerda , Adulto , Idoso , Circulação Colateral , Constrição Patológica/diagnóstico , Constrição Patológica/fisiopatologia , Circulação Coronária , Doença das Coronárias/fisiopatologia , Teste de Esforço , Feminino , Imagem do Acúmulo Cardíaco de Comporta , Coração/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/fisiopatologia , Estudos Retrospectivos , Radioisótopos de Tálio
13.
Eur J Clin Pharmacol ; 48(3-4): 189-94, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-7589040

RESUMO

To elucidate the effect of Nicorandil on myocardial energy metabolism and myocardial sympathetic activity, we administered Nicorandil orally to eight patients with angina pectoris prior to exercise testing. Arterial and coronary sinus levels of lactate, ammonia, hypoxanthine (HX), adrenaline and noradrenaline were measured during exercise in order to determine the irrespective myocardial extraction ratios (MER). Compared to placebo, Nicorandil increased the time to development of significant ST depression (322 vs 390 s) while decreasing the maximum amplitude of ST depression (0.244 vs 0.216 mV). Heart rate, systolic blood pressure, and the rate pressure product during exercise were not significantly affected. The MER of lactate, measured during exercise, was significantly higher after Nicorandil than placebo (13.6 vs 27.9). Similarly, the MERs of ammonia and HX were significantly higher after Nicorandil (-46.0 vs 7.4% and -47.0 vs 9.9% respectively). Nicorandil, had no apparent effect on myocardial sympathetic activity as the MERs of adrenaline and noradrenaline were essentially unaffected. We conclude that Nicorandil decreased myocardial ischaemia and suppressed myocardial accelerated purine metabolism (a marker of cellular energy metabolism) during exercise in patients with angina pectoris. This effect appears not to be related to myocardial sympathetic activity.


Assuntos
Angina Pectoris/tratamento farmacológico , Exercício Físico , Coração/efeitos dos fármacos , Niacinamida/análogos & derivados , Purinas/metabolismo , Vasodilatadores/farmacologia , Administração Oral , Idoso , Pressão Sanguínea/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Niacinamida/farmacologia , Nicorandil , Efeito Placebo , Fatores de Tempo
14.
Jpn Circ J ; 58(1): 15-21, 1994 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8139087

RESUMO

To assess the perfusion reserve of coronary collateral circulation, we analyzed exercise-stress tomographic thallium-201 myocardial images in 12 patients who had total occlusion in the right coronary artery (RCA) or left circumflex coronary artery (LCX) with well-developed collateral circulation and 90% stenosis in the left anterior descending coronary artery (LAD). In 6 of the 12 patients, the collateral circulation was non-jeopardized (group A). In the remaining 6 patients, the collateral circulation was jeopardized (group B). All 6 of the patients in group A had an exercise-induced decrease in thallium uptake in the segments supplied by the occluded RCA or LCX with collateral circulation, and 3 (50%) of these 6 also showed a decrease in thallium uptake in the segments supplied by the LAD. All 6 of the patients in group B also had an exercise-induced decrease in thallium uptake in the segments supplied by the occluded RCA or LCX with collateral circulation, but none showed a decrease in thallium uptake in the segments supplied by the LAD. In conclusion, the perfusion reserve of collateral circulation is equal to or less than 90% stenosis and myocardial ischemia occurs first in the collateralized segments during exercise in patients with jeopardized collateral circulation.


Assuntos
Circulação Coronária/fisiologia , Doença das Coronárias/fisiopatologia , Teste de Esforço , Isquemia Miocárdica/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Circulação Colateral , Feminino , Coração/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/fisiopatologia , Tomografia Computadorizada de Emissão
16.
Cardiovasc Drugs Ther ; 5(6): 987-90, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1686976

RESUMO

The electrophysiological effects of urapidil, a new alpha 1-adrenoceptor antagonist, were assessed in the reserpinized guinea-pig ventricular myocardium. Urapidil suppressed the maximal rate of rise (Vmax) of steady-state action potentials elicited by the fast responses at high concentrations independently of blockade of myocardial alpha-adrenoceptors, but not the Vmax of Ca(2+)-dependent slow action potentials of partially depolarized muscles in concentrations tested (up to 1.1 mM). Urapidil at high concentrations prolonged the action potential durations of the fast and slow responses in a manner similar to the quinidine-like antiarrhythmic drugs. These results suggest that the inhibitory effect of urapidil on the slow inward Ca2+ current and the Na+ current is in practice negligible.


Assuntos
Antagonistas Adrenérgicos alfa/farmacologia , Coração/efeitos dos fármacos , Piperazinas/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Cálcio/farmacologia , Cálcio/fisiologia , Cobaias , Coração/fisiologia , Ventrículos do Coração/efeitos dos fármacos , Técnicas In Vitro , Soluções Isotônicas , Potássio/farmacologia , Função Ventricular
17.
Eur J Pharmacol ; 179(3): 447-51, 1990 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-2163858

RESUMO

Under whole cell patch conditions, 1389-S blocked the INa in guinea-pig ventricular myocytes under steady state conditions (Kdrest = 30 microM, Kdi = 2.4 microM) with a shift of the inactivation curve to the hyperpolarizing direction. Both brief and long conditioning pulses could produce a use-dependent block of 1389-S. These results suggest that 1389-S had a higher affinity to the inactivated than to the rested state under steady state conditions and had a higher affinity to the activated state during train pulses as well as to the inactivated state, making channels unavailable for conduction upon activation.


Assuntos
Miocárdio/metabolismo , Propanolaminas/farmacologia , Canais de Sódio/efeitos dos fármacos , Animais , Estimulação Elétrica , Cobaias , Coração/efeitos dos fármacos , Coração/fisiologia , Técnicas In Vitro , Miocárdio/citologia
18.
Brain Res ; 514(1): 15-21, 1990 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-2162708

RESUMO

Binding sites labeled by [3H]p-aminoclonidine [( 3H]PAC) were investigated by the competitive analysis with imidazoline and non-imidazoline derivatives. Phenylethylamine derivatives displaced only the part of specific sites for [3H]PAC, which was considered as alpha 2-adrenoceptor, whereas imidazoline derivatives, such as clonidine and tolazoline, competed for a further specific binding of [3H]PAC to the non-adrenergic sites, in addition to the alpha 2-adrenoceptor. Because the non-adrenergic sites were specific for the imidazoline structure, they were termed imidazoline sites. The imidazoline sites were not distributed uniformly among rat brain regions. In striatum, hippocampus and medulla oblongata, they occupied 39.6, 33.0 and 36.5% of the specific binding of [3H]PAC, respectively. Saturation isotherms revealed that Kd and Bmax of imidazoline sites for [3H]PAC were 3.09 +/- 0.59 nM, 27.4 +/- 1.7 fmol/mg protein and 2.23 +/- 0.29 nM, 21.0 +/- 1.5 fmol/mg protein in striatum and hippocampus, respectively. Because imidazoline binding sites also displayed weak affinities for imidazole compounds, such as histamine and cimetidine, the imidazoline site may be a subtype of histamine H2-receptor.


Assuntos
Encéfalo/metabolismo , Clonidina/análogos & derivados , Imidazóis/metabolismo , Receptores Adrenérgicos alfa/metabolismo , Receptores de Droga/metabolismo , Animais , Ligação Competitiva , Clonidina/metabolismo , Receptores de Imidazolinas , Masculino , Ratos , Ratos Endogâmicos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...