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An investigation of α‐methyl amino‐acids and their derivatives on isolated tissue preparations
Author(s) -
GULATI O. D.,
PARIKH H. M.,
RINGE S. Y.,
SHERLEKAR M. L.
Publication year - 1970
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1970.tb10647.x
Subject(s) - metaraminol , tyramine , reserpine , chemistry , alpha (finance) , tyrosine , endocrinology , medicine , pharmacology , biochemistry , biology , blood pressure , construct validity , nursing , patient satisfaction
Summary1 . 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.