RESUMEN
Plasma renin activity (PRA), aldosterone (PA) and dopamine-beta-hydroxylase activity (DBH) were measured in 49 subjects over 70 years of age, selected for normal or high blood pressure level. By comparison with younger controls, elderly subjects exhibited lower supine or upright PRA, but similar PA and DBH. No relationship could be found between individual blood pressure, and PRA, PA or DBH. The data favor the view that the renin-angiotensin-aldosterone system does not play an important causative role in elderly hypertension. They also point to the necessity of age-matched controls when this system is being studied in elderly patients.
Asunto(s)
Aldosterona/sangre , Presión Sanguínea , Dopamina beta-Hidroxilasa/sangre , Renina/sangre , Anciano , Femenino , Humanos , Hipertensión/etiología , Masculino , Sistema Renina-AngiotensinaAsunto(s)
Aldosterona/sangre , Dopamina beta-Hidroxilasa/sangre , Hipertensión/sangre , Renina/sangre , Anciano , Femenino , Humanos , Masculino , PosturaRESUMEN
Haemodynamic studies were made on 31 patients with labile hypertension at rest and during exercise. Plasma renin activity (PRA) was measured in 8 of them. Five haemodynamic types could be recognised and they could be arranged into two groups. The first was characterised by an increase of calculated peripheral resistance, sometimes permanent, sometimes revealed by effort, sometimes in relation to an increased cardiac output; this would appear to predict the development of permanent hypertension. The second group was characterised by normal systemic resistances, adapted to the cardiac output which was either normal or increased; the significance of labile hypertension in these cases was uncertain; from the haemodynamic studies one was unable to distinguish a transient emotive hypertension from potential permanent hypertension. The PRA was raised in the supine position and greatly increased by an orthostatic posture in the 8 patients tested, suggesting therefore an underlying neuro-adrenergic mechanism. In some patients with labile hypertension the haemodynamic tests were normal at rest and during effort. Others had different responses, which may be the result of varieties of hyper-sympathetic activity, either pure or predominantly beta-adrenergic (increased cardiac output, peripheral resistance adapted to the output) or combined beta and alpha (increased cardiac output with raised peripheral resistance) or mainly alpha-adrenergic (normal cardiac output, increased peripheral resistance).
Asunto(s)
Hemodinámica , Hipertensión/fisiopatología , Renina/sangre , Adulto , Volumen Sanguíneo , Gasto Cardíaco , Femenino , Humanos , Hipertensión/sangre , Masculino , Esfuerzo Físico , Postura , Resistencia VascularRESUMEN
Plasma renin activity (PRA) was increased and highly sensitive to stimulation in eight cases of labile hypertension (HT), which were also studied haemodynamically. This increase in PRA would appear to result from neuro-adrenergic hyperactivity. The haemodynamic were characterised by a diversity which may be explained on the basis of differentiated sympathetic hyperactivity: exclusive or predominant beta-adrenergic activity causing a hyperkinetic cardiac state with moderate HT adapted to the increased cardiac output; A simultaneous alpha- and beta-adrenergic activity resulting in cardiac hyperkinesis with a relative or potential increase in peripheral resistance; isolated or predominant alpha-adrenergic hyperactivity causing a potential increase in peripheral resistance revealed or increased by effort, in the presence of a normal cardiac output. In certain cases of labile HT however, despite an increased PRA, haemodynamic findings were normal at rest and with effort, at the time of catheterisation.