Abnormal arginine vasopressin response to cigarette smoking and metoclopramide (but not to insulin-induced hypoglycemia) in elderly subjects
Article Abstract:
Arginine vasopressin (AVP) is a hormone that causes blood vessels to constrict and blood pressure to rise. AVP is released in response to nervous stimulation when a person changes posture, or the osmolality of the blood changes, or by a number of different mechanisms that stimulate nervous activity in the baroreflex pathway. Recent studies have shown that aging increases AVP release when osmotic stimuli are operating, but that aging decreases AVP response in relation to stimuli produced by postural changes. Metoclopramide (MCP), a drug that directly affects the baroreflex pathway, has also been found to stimulate AVP secretion in elderly subjects. This study examined whether such increases in AVP secretion also occurred in response to smoking and to insulin-induced hypoglycemia (low blood sugar). Thirty men, all heavy smokers, were examined for AVP secretion in response to MCP, smoking, and insulin-induced hypoglycemia. The men were separated into three groups based upon age: 22 to 39 years, 42 to 60 years, and 63 to 81 years. Basal AVP levels were similar for all three groups. AVP response to MCP was significantly greater in the oldest group than in the younger groups, with a peak AVP 2.5 times that of the basal level. Smoking increased AVP levels in all three groups, with increases to 2.5 times basal levels in the two younger groups and 3.25 times basal in the oldest group. The responses to insulin were similar in all three groups. These results show that AVP release increases with age in response to some stimuli, but not others. This suggests that aging causes changes that result in some signals being distorted, which affects the cells that produce AVP; thus some pathways are affected by aging, but others are not. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journals of Gerontology
Subject: Seniors
ISSN: 0022-1422
Year: 1991
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Postural stability and associated physiological factors in a population of aged persons
Article Abstract:
Control of posture involves many of the body's sensory and motor systems, including vision and balance. The functioning of these systems tends to decline with aging, and it has been suggested that these changes contribute to the postural problems that are common in the aged. Little research, however, has been done to show such a relationship. A sample of 95 persons living in a hostel for the aged was studied to evaluate the effects of several sensory and motor factors on postural stability. Average age of the subjects was 82.7 years; they were generally independent in their daily functioning, and they were mobile. All subjects were tested for visual acuity and contrast sensitivity, touch sensation, sense of the position of their joints, sense of vibration, and balance. Muscular strength was measured, ankle strength was tested, reaction time was assessed, and sway was measured while subjects were instructed to remain standing in a stationary position. The results showed associations between postural instability and reduced sensory awareness, muscle weakness in the legs, and increased reaction time to sensory information. Peripheral sensation was the single most important sensory factor for maintenance of good posture. This study therefore concluded that postural stability is associated with physiological factors in aged persons. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journals of Gerontology
Subject: Seniors
ISSN: 0022-1422
Year: 1991
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- Abstracts: Body fat distribution in healthy young and older men. Can an index of aging be constructed for evaluating treatments to retard aging rates? A 2,462-person study
- Abstracts: Can an index of aging be constructed for evaluating treatments to retard aging rates? A 2,462-person study. Aging as a modulator of respiratory sinus arrhythmia