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OUTPUT OF SYMPATHETIC TRANSMITTER IN THE ISOLATED RABBIT EAR
Author(s) -
Lande IS,
Paton WDM,
Waud Barbara
Publication year - 1968
Publication title -
australian journal of experimental biology and medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0004-945X
DOI - 10.1038/icb.1968.179
Subject(s) - bioassay , stimulation , perfusion , phenoxybenzamine , anatomy , chemistry , medicine , endocrinology , small intestine , nerve stimulation , biology , propranolol , genetics
Summary The release of sympathin in response to periarterial nerve and ventral auricular nerve stimulation in the isolated perfused rabbit ear has been measured by bioassay of the perfusate on the electrically stimulated rat colon and, in some experiments, by bioassay on a second perfused ear. The output was extremely small, the maximum amount of sympathin recorded being 27 pg. per pulse. In a number of preparations, sympathin was not detected in the perfusate. Loss of noradrenaline by re‐uptake into storage sites is probably not the major factor responsible for the difficulty in detecting sympathin, since injected noradrenaline showed only a small loss during its passage through the ear and the output remained low in the presence of phenoxybenzamine and cocaine. The possibility is considered that the small quantities of sympathin detected in the perfusate reflect either a small overflow of transmitter or a genuinely low output of sympathin in the ear vessels compared with tissues such as heart spleen and intestine. Attention is drawn to the ability of the central artery alone to reproduce much of the resistance to perfusion observed in the whole ear in response to periarterial stimulation and to noradrenaline.