| Autor: |
Davies, I. B., Mathias, C. J., Sudera, D., Sever, P. S. |
| Zdroj: |
Journal of Cardiovascular Pharmacology; January 1982, Vol. 4 Issue: Supplement 1 pS139-S144, 6p |
| Abstrakt: |
Plasma noradrcnalinc concentrations, platelet a-receptor prop-erties. and the blood pressure responses to intravenous noradrcnalinc were measured in 14 normal subjects. 6 patients with phaeochromoeytoma. 9 patients with multiple System atrophy and sympathetic nervous system degener-ation (MSA. Shy—Drager syndrome), and 12 tetraplegic patients (cord tran-sections C4-C8). Plasma noradrenaline concentrations at rest were about 10 times normal in phaeochromoeytoma. one-tenth normal in MSA. and about one-half normal in tetraplegics. Conversely, the platelet a-receptor number was decreased in phaeochromoeytoma and increased in MSA. i.e., platelet a-receptor numbers were inversely related to plasma noradrenaline concentrations. Platelet a-receptor numbers were normal in tetraplegics. Platelet a-receptor affinity did not change in any group. Blood pressure responses to intravenous noradrenaline were greater than normal in the 9 MSA patients, but were decreased in one patient with phaeochromoeytoma. The inverse relation-ship between noradrenaline concentrations, platelet a-receptor numbers. and blood pressure responses to intravenous. exogenous. noradrenaline may mean that endogenous adrenergic agonist concentrations; in man. may regulate a-receptor properties and so may determine, in part, a-receptor mediated biological responses. In tetraplegics. frequent but intermittent exposure to high concentrations of noradrenaline during the activation of spinal sympathetic reflexes may prevent an increase in a-receptor number even though. in the resting state, exposure of adrenergic receptors to agonist is low as refleeted by the low plasma noradrenaline concentration. In tetraplegics. the increased pressor response to noradrenaline may be due only to impairment of baro-reflexes. |
| Databáze: |
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