ISSN:
1432-1912
Keywords:
Neuronal noradrenaline carrier
;
Inhibition of transport-Na+-dependence
;
Desipramine
;
Cocaine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. Vasa deferentia obtained from reserpine-pretreated rats were incubated (monoamine oxidase and catechol-O-methyltransferase inhibited) in media containing various concentrations of3H-(−)noradrenaline and Na+ and initial rates of the neuronal uptake of3H-noradrenaline measured both in the absence and presence of uptake inhibitors after 1 min of incubation. 2. When rates of uptake were determined at various3H-noradrenaline (1.0–12.2 μmol/l) and two fixed Na+ concentrations (25 and 140 mmol/l), the inhibition of uptake produced by (+)amphetamine, (−)metaraminol, desipramine, nomifensine and cocaine was competitive with respect to3H-noradrenaline at both Na+ concentrations. While theK i for (+)amphetamine, (−)metaraminol desipramine and nomifensine increased when the Na+ concentration was lowered, that for cocaine decreased. 3. When the Na+ concentration was varied (10–140 mmol/l) and the3H-noradrenaline concentration held constant (1.2 μmol/l), (+)amphetamine, (−)metaraminol, nomifensine and desipramine acted as mixed-type inhibitors with respect to Na+, and the inhibition of uptake produced by these drugs was the more pronounced, the higher the Na+ concentration. On the other hand, cocaine was competitive with Na+ and the inhibition produced by this drug was the more pronounced, the lower the Na+ concentration. 4. It is concluded that the inhibitors of neuronal uptake tested here act in dependence on the external Na+ concentration. Desipramine and nomifensine resemble alternative amine substrates in being more potent at high than at low Na+ concentrations. On the other hand cocaine is more potent at low than at high Na+ concentrations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00569377
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