Introduction. Patients with Parkinson's disease (PD) showed reduced myocardial 123I-MIBG uptake, which may affect autonomic regulation. We investigated correlation between MIBC accumulation and cardiovascular autonomic function in PD. Methods. We performed myocardial MIBG scintigraphy, heart rate variability (HRV) analysis, and the head-up tilt test (HUT) in 50 PD patients (66.4 ± 7.8 years; duration 5.5 ± 5.9 years). Autonomic function tests were also performed in 50 healthy controls (66.5 ± 8.9 years). As HRV parameters, a high-frequency power (HF, 0.15–0.4 Hz), a low-frequency power (LF, 0.04–0.15 Hz), and LF/HF ratio were used. Results. Our PD patients had a significant reduction in LF and HF compared with the controls (P = 0.005 and P = 0.01). In HUT, systolic and diastolic blood pressure falls in the PD group were significantly greater than those in the controls (P = 0.02 and P = 0.02). The washout rate of MIBG was negatively correlated with blood pressure changes during HUT. Conclusion. Our PD patients showed reduced HRV, blood pressure dysregulation, and reduced MIBG accumulation, which was correlated with blood pressure dysregulation. Orthostatic hypotension in PD may be mainly caused by sympathetic postganglionic degeneration.
Postprandial hypotension (PPH) is a major clinical problem in patients with autonomic failure such as that observed in multiple system atrophy (MSA). The pathophysiology of PPH remains unclear, although autonomic dysfunction and gastrointestinal vasoactive peptides have been suspected to participate in its pathogenesis. We measured blood pressure and plasma levels of glucose, insulin, noradrenaline, neurotensin, glucagon-like peptide (GLP)-1 and GLP-2 before and after meal ingestion in 24 patients with MSA to reveal the roles of the autonomic nervous system and gastrointestinal vasoactive peptides in PPH. We performed a second meal-ingestion test by administering acarbose to evaluate the effects of acarbose (an α-glucosidase inhibitor) on PPH and vasoactive peptides in 14 patients with MSA and PPH. We also evaluated blood pressure responses to the head-up tilt test and heart rate variability in all the patients. Severities of PPH and orthostatic hypotension were significantly correlated. Patients with PPH had significantly worse orthostatic hypotension and lower heart rate variability than those without PPH. Postprandial GLP-1 secretion was higher in patients with PPH than in those without PPH. No significant differences were observed in the postprandial increases in plasma levels of glucose, insulin, noradrenaline, neurotensin or GLP-2. Acarbose significantly attenuated postprandial hypotension and tended to decrease GLP-2 secretion. Our results indicate that autonomic failure is involved in the pathogenesis of PPH and confirm that acarbose has a preventive effect against PPH in patients with MSA. Decreased postprandial secretion of GLP-2, which increases intestinal blood pooling, may attenuate PPH in patients with MSA.
Objective The autoimmune mechanism is considered to play an important role in the development of acquired idiopathic generalized anhidrosis (AIGA), and muscarinic M3 receptors (M3Rs) on eccrine glands are possible autoimmune targets. We investigated the existence of autoantibodies against M3Rs in AIGA patients. Methods We immunostained M3R-expressing cultured cells with the serum of 12 AIGA patients (mean age: 35.0±11.7 years, mean disease duration: 26.6±25.8 months) and 10 healthy subjects (mean age: 32.4± 10.4 years). Results The surface of the M3R-expressing cells was stained by the serum obtained from one of the 12 AIGA patients but not by the serum obtained from the remaining 11 patients or healthy subjects. Conclusion The presence of M3R autoantibodies may therefore be related to the underlying mechanism of disease in a subset of AIGA patients.
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