Is Orthostatic Hypotension in the Elderly due to Autonomic Failure?

• Published in: Age and ageing 1990-09, Vol.19 (5), p.288-296
• Main Authors: ROBINSON, B. J., STOWELL, L. I., JOHNSON, R. H., PALMER, K. T.
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Autonomic Nervous System - physiopathology; Blood; Blood Platelets - metabolism; Blood Pressure; Cardiovascular disease; Causes of; Diseases; Dysautonomia; Elderly; Female; Health care; Heart Rate; Humans; Hypotension, Orthostatic; Hypotension, Orthostatic - blood; Hypotension, Orthostatic - physiopathology; Lymphocytes - metabolism; Male; Medical research; Norepinephrine - blood; Older people; Orthostatic hypotension; Receptors, Adrenergic - analysis; Space life sciences; Vasopressins - blood
• ISSN: 0002-0729; 1468-2834
• DOI: 10.1093/ageing/19.5.288

In order to investigate whether orthostatic hypotension in elderly people is due to autonomic nervous system dysfunction or blood vessel abnormalities, we have measured platelet and lymphocyte adrenoceptor numbers and agonist binding in addition to venous plasma catecholamine concentrations. Eight elderly subjects with orthostatic hypotension and six control elderly subjects were studied. None of the subjects had other symptoms of autonomic failure. There was no significant difference between the heart rate or plasma catecholamine responses to standing of the two groups. The orthostatic hypotension subjects had a significant rise of their plasma vasopressin levels whereas the control group had no significant change. The number of α2-adrenoceptor sites in platelets was lower in the orthostatic hypotensive group compared to the controls and the binding affinity was greater than in the controls. There were no significant differences in β-adrenoceptor binding sites or affinities in isolated lymphocytes between the two groups. The similar changes in heart rate and catecholamines together with the vasopressin changes suggest that, in these elderly patients with an abnormal drop of blood pressure on standing, there is no dysfunction of autonomic pathways concerned with cardiovascular function. The lower numbers of α2-adrenoceptor sites on isolated platelets in subjects with orthostatic hypotension could indicate reduced α2-adrenoceptor numbers on their blood vessels which could contribute to their inability to maintain blood pressure while standing.