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SOME OBSERVATIONS ON THE PHARMACOLOGY OF α‐METHYLDOPA
Author(s) -
DAY M. D.,
RAND M. J.
Publication year - 1964
Publication title -
british journal of pharmacology and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0366-0826
DOI - 10.1111/j.1476-5381.1964.tb01545.x
Subject(s) - nictitating membrane , vas deferens , methyldopa , reserpine , tyramine , cats , norepinephrine , endocrinology , medicine , stimulation , chemistry , blood pressure , ileum , clonidine , pharmacology , dopamine , statistics , classical conditioning , mathematics , conditioning
α‐Methyldopa in high concentrations impaired the responses of rabbit isolated ileum and guinea‐pig isolated vas deferens to stimulation of the sympathetic nerves and to noradrenaline, but these preparations taken from animals previously treated with α‐methyldopa showed no sign of impairment. Contractions of the cat nictitating membrane were reduced but not abolished by α‐methyldopa. In cats, dogs and rats, pressor responses to noradrenaline were usually slightly increased by α‐methyldopa. Pressor responses to tyramine were not affected consistently. α‐Methyldopa, α‐methyldopamine and α‐methylnoradrenaline behaved like dopa, dopamine and noradrenaline respectively in restoring the responses of tissues from reserpine‐treated animals to stimulation of the sympathetic nerves to the rabbit ileum, the guinea‐pig vas deferens and the cat nictitating membrane and in restoring responses to tyramine of the cat blood pressure and nictitating membrane, and the rat blood pressure. The potency of α‐methylnoradrenaline relative to noradrenaline ranged from one‐half to one‐ninth on various preparations. The results are discussed in relation to the anti‐hypertensive action of α‐methyldopa.