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The effects of pargyline on overflow of transmitter and uptake of noradrenaline in the cat spleen
Author(s) -
BLAKELEY A. G. H.,
POWIS G.,
SUMMERS R. J.
Publication year - 1973
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.1476-5381.1973.tb08199.x
Subject(s) - pargyline , stimulation , endocrinology , monoamine oxidase , tyramine , medicine , chemistry , norepinephrine , dopamine , biology , enzyme , biochemistry
Summary1 Twenty minutes after the addition of pargyline (5 × 10 −4 M) to blood perfusing the isolated spleen of the cat, the overflow of transmitter resulting from stimulation of the sympathetic nerves increased 2–3–3‐fold. Lower doses of pargyline did not significantly affect overflow. 2 Monoamine oxidase activity, measured with either radioactively labelled tyramine or noradrenaline as substrate, was almost completely inhibited by doses of pargyline in the range of 10 −4 M to 5 × 10 −4 M. Inhibition of enzyme activity was not correlated with the effect on overflow. Pargyline had only a slight inhibitory effect on catechol‐ O ‐methyl transferase. 3 Uptake of a 1 μg injection (pulse) of labelled noradrenaline, following pargyline (5×10 −4 M), was increased to 199·1% of that found in control experiments. 4 Pargyline significantly reduced the vascular responses to nerve stimulation but had no significant effect on capsular responses. 5 The inhibitor had no effect on resting overflow of labelled noradrenaline from the spleen but doubled the overflow of labelled noradrenaline following nerve stimulation. 6 It is suggested that the effect of pargyline on overflow is due to increased release of transmitter during nerve stimulation. 7 The possible clinical significance of these findings is discussed.