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. 1974 Aug;51(4):473–480. doi: 10.1111/j.1476-5381.1974.tb09664.x

The cardiovascular effects of L-dopa in the pithed rat

E Eden, PA Nasmyth
PMCID: PMC1778065  PMID: 4451761

Abstract

1 L-DOPA (1-2 mg i.v.) in the pithed rat reduced the arterial and increased the venous pressure responses to noradrenaline.

2 Infusions of dopamine (4-8 μg kg-1 min-1) and noradrenaline (500 ng kg-1 min-1) also reduced the pressor responses to noradrenaline. The pressor response did not recover after stopping dopamine infusions, but it usually did so after stopping noradrenaline infusions.

3 The effect of L-DOPA on the response to noradrenaline was prevented by the prior injection of the dopa decarboxylase inhibitor NSD 1024.

4 The prior injection of the dopamine-β-hydroxylase inhibitor diethyldithiocarbamate, only partially prevented the effect of L-DOPA on pressor responses to noradrenaline.

5 The perfusion of noradrenaline (400 ng kg-1 min-1) together with Krebs solution (10 ml/min) through an organ bath containing an isolated aortic strip, depressed the response of the strip to doses of noradrenaline after the infusion was stopped. Infusions of dopamine (0.5-8.0 μg kg-1 min-1) had a similar effect. Fifteen minutes after adding L-DOPA (0.5 mg) to the bath and 10 min after washing it out, the response to noradrenaline was depressed in three out of four experiments.

6 Infusions of noradrenaline (1 μg kg-1 min-1) in an isolated heart perfused by Langendorf's method blocked the response to injected noradrenaline whilst perfusion was in progress. Infusions of dopamine (4-8 μg kg-1 min-1) or of L-DOPA (200 μg kg-1 min-1) did not have this effect.

7 It is concluded that the effect of L-DOPA on pressor responses to noradrenaline in the pithed rat are mediated by its conversion to dopamine and noradrenaline.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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