RESUMEN
In the present study, the effects of L-dopa treatment on cardiovascular variables and peripheral venous tone were assessed in 13 patients with Parkinson's disease (PD) with Hoehn and Yahr stages 1-4. Patients were investigated once with their regular treatment and once after 12 h of interruption of L-dopa treatment. L-Dopa intake significantly reduced systolic and diastolic blood pressure, heart rate and plasma noradrenaline and adrenaline in both the supine and upright (60 degrees ) positions. A significant reduction in stroke volume and cardiac output was also seen with L-dopa. The vascular status of the legs was assessed through thigh compression during leg weighing, a new technique developed in our laboratory. Healthy subjects were used to demonstrate that this technique provided reproducible results, consistent with those provided by strain gauge plethysmography of the calf. When using this technique in patients with PD, L-dopa caused a significant lowering of vascular tone in the lower limbs as shown, in particular, by an increase in venous distensibility. Combined with the results of the orthostatic tilting, these findings support that the treatment-linked lowering of plasma noradrenaline in patients with PD was concomitant with a significant reduction in blood pressure, heart rate and vascular tone in the lower limbs. These pharmacological side-effects contributed to reduce venous return and arterial blood pressure which, together with a lowered heart rate, worsened the haemodynamic status.
Asunto(s)
Antiparkinsonianos/efectos adversos , Pierna/irrigación sanguínea , Levodopa/efectos adversos , Enfermedad de Parkinson/tratamiento farmacológico , Adulto , Anciano , Presión Sanguínea/efectos de los fármacos , Gasto Cardíaco/efectos de los fármacos , Dopaminérgicos , Epinefrina/sangre , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Pierna/patología , Masculino , Persona de Mediana Edad , Norepinefrina/sangre , Tamaño de los Órganos/efectos de los fármacos , Enfermedad de Parkinson/sangre , Enfermedad de Parkinson/fisiopatología , Pletismografía , Postura , Reproducibilidad de los Resultados , Pruebas de Mesa InclinadaRESUMEN
The objectives to determine both the contribution to orthostatic intolerance (OI) of calf venous volume during a stand-test, and the effects of a combined eccentric-concentric resistance exercise countermeasure on both vein response to orthostatic test and OI, after 90-day head-down tilt bed-rest (HDT). The subjects consisted of a control group (Co-gr, n = 9) and an exercise countermeasure group (CM-gr, n = 9). Calf volume and vein cross-sectional area (CSA) were assessed by plethysmography and echography during pre- and post-HDT stand-tests. From supine to standing (post-HDT), the tibial and gastrocnemius vein CSA increased significantly in intolerant subjects (tibial vein, +122% from pre-HDT; gastrocnemius veins, +145%; P < 0.05) whereas it did not in tolerant subjects. Intolerant subjects tended to have a higher increase in calf filling volume than tolerant subjects, in both sitting and standing positions. The countermeasure did not reduce OI. Absolute calf volume decreased similarly in both groups. Tibial and gastrocnemius vein CSA at rest did not change during HDT in either group. During the post-HDT stand-test, the calf filling volume increased more in the CM-gr than in the Co-gr both in the sitting (+1.3 +/- 5.1%, vs. -7.3 +/- 4.3%; P < 0.05) and the standing positions (+56.1 +/- 23.7% vs. +1.6 +/- 9.6%; P < 0.05). The volume ejected by the muscle venous pump increased only in the CM-gr (+38.3 +/- 21.8%). This study showed that intolerant subjects had a higher increase in vein CSA in the standing position and a tendency to present a higher calf filling volume in the sitting and standing positions. It also showed that a combined eccentric-concentric resistance exercise countermeasure had no effects on either post-HDT OI or on the venous parameters related to it.