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Changes in Sympathetic Nerve Terminals in the Heart of Cold‐Exposed Rats
Author(s) -
Fillenz M.,
Stanford S. C.,
Coles B. G.
Publication year - 1993
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1993.tb03547.x
Subject(s) - dopamine , medicine , catecholamine , endogeny , chemistry , norepinephrine , vesicle , endocrinology , tyrosine hydroxylase , biology , biochemistry , membrane
Changes in sympathetic nerve terminals of the heart after varying periods of exposure of rats to 4°C were investigated. Two indices were used for changes in the number of noradrenaline storage vesicles, i.e., vesicular dopamine β‐hydroxylase (DBH) activity and noradrenaline storage capacity. The latter was obtained after uptake of [ 3 H]noradrenaline; endogenous content, uptake of exogenous noradrenaline, and degree of saturation of the vesicles were calculated using the specific activity of the [ 3 H]noradrenaline. As a measure of tyrosine hydroxylase activity, whole ventricular noradrenaline, dopamine, and dihydroxyphenylacetic acid content were used. After 4 h of cold exposure there was an increase in vesicular endogenous noradrenaline content, uptake, storage capacity, and DBH activity as well as a large increase in whole ventricular dopamine. After 6 h in the cold, vesicular endogenous noradrenaline content, storage capacity, and DBH activity were decreased. The results suggest that during cold exposure there is an initial increase followed by a decrease in the number of functional vesicles in the nerve terminal, which could explain the fluctuations in the rate of noradrenaline release.