Effects of acute levodopa administration on blood pressure and heart variability in never treated parkinsonians

The effects of levodopa on autonomic nervous system (ANS) were investigated through the measurement of blood pressure (BP) and heart rate (HR) variability in 15 de novo parkinsonian who never received dopaminergic drugs. BP and HR were obtained using digital photoplethysmography in supine and standing positions. Measurements were achieved 90 min after administration, in a double blind cross-over way, of placebo or levodopa (200 mg)+benserazide (50 mg). Spectral analysis was performed using fast Fourier transformation (FFT) on 512 consecutive SBP and HR values. Spectral modulus was integrated for calculation of total spectra and of low frequency (LF: 66-129 mHz) or high frequency band (HF: respiratory frequency +/- 50 mHz). After placebo, orthostatism was followed by a significant increase in BP and HR whereas relative variabilities in LF and HF remained unchanged. After levodopa, BP was significantly lower in supine position without changes in HR and LF. During orthostatism, changes observed in BP and in FFT were similar to those observed during placebo period. These data indicate that levodopa reduces supine and standing BP but does not impair orthostatic adaptation. This effect is not due to modification of BP or HR variability and appears to independent of any direct effect on ANS.