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Biomedical subjects

D G Johnson

Publications and source records attributed to D G Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1972

Axonal sprouts and ( 3 H)norepinephrine uptake by superior cervical ganglia in organ culture.

Superior cervical ganglia from adult rats maintained in organ culture show a progressive increase in the rate of uptake of [(3)H]norepinephrine. The enhanced uptake of norepinephrine is a consequence of the development of axonal sprouts. Formation of axonal sprouts, which appear to have many of the properties of sympathetic nerve endings, is inhibited by colchicine and vinblastine, presumably because of the interaction of these drugs with neurotubular protein.

Animals↗
PubMed1971

Proportional release of norepinephrine and dopamine- -hydroxylase from sympathetic nerves.

Dopamine-beta-hydroxylase(DBH), the enzyme that catalyzes the conversion of dopamine to norepinephrine, is localized in the vesicles containing catecholamine in sympathetic nerves. This enzyme is released with norepinephrine when the nerves to the guinea pig vas deferens are stimulated in vitro, and the amount of enzyme discharged increases as the length of stimulation periods increases. The amount of DBH released is proportional to the amount of norepinephrine released, and the ratio of norepinephrine to DBH discharged into the incubation medium is similar to that in the soluble portion of the contents of the synaptic vesicles from the vas deferens. These data are compatible with the release of the neurotransmitter norepinephrine and DBH from symnpathetic nerves by a process of exocytosis.

Animals↗
PubMed1971

Sympathetic reinnervation of the rat iris in organ culture.

Reinnervation of sympathetically denervated rat iris by superior cervical ganglion cells has been demonstrated to occur in vitro. Return of [(3)H]norepinephrine uptake by irises incubated in contact with ganglia was associated with the reappearance of nerve fibers containing catecholamines that were demonstrable by fluorescent histochemistry. The reinnervating neurons appeared to follow the same general pattern of innervation seen in the normal iris, but the density of the neural plexus was much greater. Nerve growth factor influenced the rate and extent of innervation of the iris but not of neuronal growth within the ganglion.

Animals↗