Stephen W. Carmichael

The adrenal chromaffin vesicle: an historical perspective

Unique histochemical properties of the adrenal medulla were first described in the middle of the nineteenth century. The most important histochemical reaction of this glandular tissue was with chromate salts which became known as the chromaffin reaction. The terms chromaffin cell and chromaffin vesicle stem from this reaction. During the first half of this century it was established that the chromaffin cells of the adrenal medulla are an integral part of the sympathetic nervous system and play a role in the response to acute stress. The chromaffin cell is recognized as a modified postganglionic sympathetic neuron and as such has proven to be an accessible and valuable model. Thirty years ago it was found that the secretory vesicle of the chromaffin cell could be isolated. This has led to the use of the chromaffin vesicle as a model for study of neurosecretory vesicles. This symposium presents an overview of recent work in various areas that have centered on the chromaffin vesicle.

Direct Connections between Mitochondria and Catecholamine-Storage Vesicles Demonstrated by High Voltage Electron Microscopy in Rat Adrenal Medulla*

SummaryTubular channels from mitochondria to catecholamine-storage vesicles have been demonstrated in thick sections of adrenal medullary tissue from hypoglycemia-stressed rats by the use of the high voltage electron microscope. The function of these connections is not presently known although they may serve as channels for the transport of materials such as high-energy nucleotides from one organelle to the other. The present study has examined only the adrenal medulla, but it should be considered that such connections may also exist in other neural cells and possibly other cells in which there is intracellular transport of ATP.

Adenylate cyclase activity of adrenal chromaffin vesicles

Biochemical studies have provided conflicting interpretation as to the presence of adenylate cyclase in or on the chromaffin vesicle of the adrenal medulla. Various histochemical procedures were employed and a slight amount of reaction product was detected. It is suggested that a small amount of adenylate cyclase is associated with the chromaffin vesicle.

High-voltage electron microscopy of adrenal medulla: direct connections between mitochondria and catecholamine-storage vesicles.

A high-voltage electron microscopic study of adrenal medullary cells from hypoglycemia-stressed rats revealed the existence of tubular channels which create a luminal continuity between the mitochondrial compartment and the catecholamine-storage vesicles. It is suggested that these channels allow for the transfer of materials such as high-energy nucleotides between the mitochondria and the catecholamine-storage vesicles without an intervening membrane.

Electron microscopy of the adrenal medulla of the newborn dog under hypothermia and asphyxia

The left adrenal medullas of 20 (5 litters of 4) day-old dogs were studied with the electron microscope. The right adrenal medullas of the same animals had been examined by fluorescence microscopy and the results reported previously. In each litter one animal served as a coenothermic (37 degrees C) and one a hypothermic control (15 degrees C). The third animal (at 37 degrees C) was asphyxiated until twice its time of last gasp (about 32 min) and the fourth was cooled to 15 degrees C and asphyxiated for the same length of time as the third animal. The induction of hypothermia (to 15 degrees C) in unanesthetized puppies results in a decrease (32%) in dense-cored granules, an enlargement of mitochondria, and slight dilation of the endoplasmic reticulum. In coenothermic puppies asphyxiation to twice the time of last gasp is accompanied by the following changes: loss of dense-cored granules (52%); swelling of nuclei; clumping and marginal aggregation of nuclear chromatin material; dilation of the endoplasmic reticulum; swelling, loss of cristae and rarefaction of the matrices of mitochondria. The changes in some cells were greater than others. Many of these changes are considered to demonstrate anoxic damage. Under the conditions of the present experiments, hypothermia protected most of the adrenal medullary cells from anoxic damage.