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. 1970 Dec;40(4):689–701. doi: 10.1111/j.1476-5381.1970.tb10647.x

An investigation of α-methyl amino-acids and their derivatives on isolated tissue preparations

O D Gulati, H M Parikh, S Y Ringe, M L Sherlekar
PMCID: PMC1702915  PMID: 5495174

Abstract

1. The ability of α-methyl amino-acids and their corresponding amines to restore the sympathomimetic actions of tyramine, and the uptake of the amino-acids and the amines, were studied in isolated tissue preparations obtained from reserpine pretreated animals.

2. Tyramine relaxed isolated rat ileum preparations from non-reserpinized rats but not from reserpine treated animals. α-Methyldopa, α-methylnoradrenaline and lower concentrations of metaraminol restored the responses of reserpinized preparations. α-Methyldopamine, α-methyl-m-tyrosine, α-methyl-p-tyrosine and higher concentrations of metaraminol did not do so. The restoring effect of α-methyldopa was blocked by disulphiram. α-Methyl-p-tyrosine or α-methyl-m-tyrosine blocked the restoring action of α-methyldopa but not of α-methylnoradrenaline. Cocaine blocked the restoration of responses to tyramine by α-methylnoradrenaline but not by α-methyldopa. α-Methyldopa and α-methylnoradrenaline failed to restore responses to tyramine in the presence of sodium-free Tyrode solution.

3. Tyramine increased the perfusion pressure in isolated rabbit ear preparations obtained from non-reserpinized animals but was very much less active in preparations obtained from reserpine treated animals. α-Methyldopa, α-methyl-m-tyrosine, α-methylnoradrenaline, α-methyl-p-tyrosine and metaraminol restored the effects of tyramine. α-Methyldopamine did not do so. The restoring effect of α-methyldopa and α-methyl-m-tyrosine was blocked by disulfiram. α-Methyl-p-tyrosine blocked the restoring effect of α-methyl-m-tyrosine.

4. Tyramine produced positive inotropic effects in isolated rabbit heart preparations. This was either reduced or absent in preparations obtained from reserpine pretreated animals. α-Methyldopa, α-methylnoradrenaline, α-methyl-m-tyrosine and metaraminol restored the responses to tyramine. α-Methyldopamine and α-methyl-p-tyrosine did not do so.

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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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