Showing papers by "Michael G. Ziegler published in 1976"
TL;DR: Levels of norepinephrine in human plasma have been determined by a radioenzymatic technique sufficiently sensitive to measure 0.014 ng NE per ml plasma by evaluating sympathetic neuronal function based on the increments in plasma NE produced by postural change and a standard amount of exertion.
590 citations
TL;DR: Extending the study to teenage and elderly subjects revealed that basal levels of plasma NA correlate with age and that the increase in plasma NA in response to stress is similarly related to age.
Abstract: WE measured plasma noradrenaline (NA) levels in about 20 individuals who were to serve as normal control subjects and noted that older subjects tended to have higher NA levels. Extending the study to teenage and elderly subjects revealed that basal levels of plasma NA correlate with age and that the increase in plasma NA in response to stress is similarly related to age. There is considerable evidence that sensitivity to NA and NA metabolism change with increasing age. In rabbits and cats the threshold for cardiovascular response to low levels of NA decreases with old age1. In ageing rats uptake of NA into the heart is greater than in young animals2 and there is a diminished inotropic response of aged rat myocardium to a fixed concentration of NA (ref. 3). Cardiac monoamine oxidase activity increases severalfold during the life span of a rat while dopa decarboxylase decreases during the first year2. In man, propranalol, which blocks β-adrenergic receptors, reduces heart rate and cardiac output during exercise, but this effect is considerably smaller in older subjects4. The response of heart rate to hypoxia and hypercapnia is attenuated in older men5.
457 citations
TL;DR: The view that hypertension and hypotension in dysautonomia are related to the rate of norepinephrine release is supported.
Abstract: Norepinephrine concentration and dopamine-beta-hydroxylase activity were measured in the plasma of 10 dysautonomic patients and 10 normal subjects while they were reclining, standing and e...
113 citations
TL;DR: Sensitive fluorometric and radioenzymatic assays make analysis of the small amount of norepinephrine present in the brain possible so that the authors know a great deal about this chemical that occurs in such small amounts.
87 citations
TL;DR: Inhibition of dopamine-beta-hydroxylase provides a useful pharmacologic approach to evaluating the role of norepinephrine in psychiatric disorders.
Abstract: Dopamine-beta-hydroxylase, the enzyme responsible for conversion of dopamine to norepinephrine, is released along with catecholamines from the adrenal medulla and from sympathetic nerve endings. The properties and mechanisms of the enzyme's action are discussed and its distribution described. Dopamine-beta-hydroxylase is a valuable indicator of exocytosis as a mechanism for neurotransmitter release. The enzyme is present in plasma, but its levels vary widely between individuals. This variation seems to be related more to genetic factors than to sympathetic nerve activity. Abnormally high or low plasma levels are associated with several diseases. However, the relation of these levels to disease pathogenesis rather than to genetic determinants is unclear. Levels of the enzyme are elevated in patients with pheochromocytoma and decline after removal of the tumor. Dopamine-beta-hydroxylase levels seem to be normal in hypertensive patients. Inhibition of dopamine-beta-hydroxylase provides a useful pharmacologic approach to evaluating the role of norepinephrine in psychiatric disorders.
73 citations
TL;DR: This study shows that the ADBH, which is presumably attached to DBH, is rapidly transported from adrenergic terminals to sympathetic ganglia and contains a fluorescent network of very fine varicose nerves.
54 citations
TL;DR: Further substantiation of the interaction between psychological disease and the onset of galactorrhea-amenorrhea is presented in women who underwent intensive psychometric and neuroendocrine evaluation prior to the use of the dopamine against 2-Br-alpha-ergocryptine (CB-154).
34 citations
Journal Article•
3 citations