A possible high molecular weight precursor to vasoactive intestinal polypeptide sequestered into pheochromocytoma chromaffin granules

Chromaffin granules, the catecholamine storage granules of pheochromocytoma were isolated from five human pheochromocytoma tumors. Vasoactive intestinal polypeptide (VIP) immunoreactivity was detected in all chromaffin granule preparations, paralleling the synthetic VIP antibody binding curve over a range of serial dilutions. In addition, gel filtration revealed an immunoreactive peptide peak coeluting with VIP. However, high molecular weight immunoreactive material was also detected on the column. This high molecular weight material was further characterized by sodium dodecyl sulfate gel electrophoresis, followed by electroblotting onto nitrocellulose paper and detection by anti-VIP antibodies with a secondary antibody conjugated to horseradish peroxidase. A 70 000 dalton immunoreactive band was identified, in which reactivity with anti-VIP antibody was inhibited by VIP; this band did not cross react with non-related antibodies. This 70 000 dalton protein may be an intermediate molecule in the biosynthesis and processing of VIP.

Ultrastructural effects of nerve growth factor on PC 12 pheochromocytoma cells in spinner culture

PC12 pheochromocytoma cells treated with nerve growth factor (NGF) for two weeks in spinner cultures quickly begin to form processes after plating on an appropriate substrate, while cells freshly exposed to NGF in monolayer culture initiate neurite outgrowth only after a lag period of several days. The present ultrastructural studies indicate that PC 12 cells treated with NGF in spinner cultures do not form neurites, but do form short extensions comparable to those which have been reported within the first two days of exposure to NGF in monolayer cultures. These extensions contain organelles believed to be required for locomotion and for transport of cytoskeletal and membrane components and neurotransmitters. They also form bulbous distensions in which numerous chromaffin-type granules accumulate. These findings suggest that NGF may affect cells in spinner cultures by promoting development or activation of axonal transport mechanisms, and that the existence of these mechanisms may contribute to the neurite outgrowth which the cells exhibit when plated. NGF-treated PC 12 cells in spinner cultures do not accumulate the agranular synaptic-like vesicles, which are typically found in comparably treated monolayer cultures and which have been hypothesized to be sites of acetylcholine storage. These and other data demonstrate that attachment to a substrate can selectively modulate the responses of PC 12 cells to NGF.

[Ultrastructural morphometric analysis of adrenaline- and noradrenaline-containing cells in rat adrenals during physical and emotional stress]

Ultrastructural organization of chromaffin cells of rat adrenal glands was studied in different stress models (48 h of running in the wheel, 48 h of immobilization, and sleep deprivation during 7 days). It was shown by ultrastructural morphometry that chromaffin cells experienced fine structural modifications (a decrease in the number of adrenaline- and noradrenaline-containing granules, swelling of mitochondria and endoplasmic reticulum). The degree of such modifications depended on a stress situation, being more pronounced during physical stress.

Subcellular fractions of the adrenal medulla. Comparison by two-dimensional polyacrylamide gel electrophoresis

Subfractions of adrenal medullary homogenates were analyzed in two-dimensional polyacrylamide gels to assess the extent of protein homology. Chromaffin granule proteins were highly acidic, with the exception of the soluble form of the enzyme dopamine beta-hydroxylase (EC 1.14.17.1). The purified granule membrane proteins were more heterogeneous, but still predominantly acidic. The soluble and membrane forms of dopamine beta-hydroxylase behaved identically in this gel system. Lactoperoxidase-catalyzed iodination of intact granules revealed that most, but not all, granule membrane proteins are accessible at the cytoplasmic face. Prominent proteins of the purified adrenal medullary mitochondria showed little if any homology with purified granule membranes. The crude microsome fraction showed significant homology with purified granule membranes despite low levels of cross-contamination between the two fractions in marker enzyme analysis. Among proteins that could be identified, dopamine beta-hydroxylase was at a low level in the microsomes, while the granule membrane protein cytochrome b-561 appeared to be in both fractions. The pattern obtained from primary cultures of adrenal chromaffin cells was very complex, but prominent proteins from the subcellular fractions were seen without difficulty. Actin and tubulin were very prominent in the whole cell pattern. Radioiodination of the whole cells resulted in a number of spots being labelled, although the majority of the label appeared to be in only two proteins of molecular weight 70000 and isoelectric point 5.7.

The distribution and ultrastructure of sensory elements in the baroreceptor region of the truncus arteriosus of the lizard Trachydosaurus rugosus

The proximal truncus arteriosus of the lizard Trachydosaurus rugosus was studied with light-, fluorescence- and electron-microscopical techniques. Three vessels comprised the truncus; the pulmonary, left aortic, and carotico-aortic arteries. Right and left truncal nerves, each derived from the ipsilateral vagus nerve, innervated the truncus, particularly its proximal 3 mm. Ultrastructurally, the nerves had a variety of appearances: some were clearly adrenergic, c-type or p-type. A number of profiles contained large numbers of mitochondria and were classified as sensory. Some profiles defied exact classification, having characteristics common to two different types of profile. Within the outer medial layers, profiles up to 7 micrometers in diameter were found. These contained large numbers of mitochondria, myelin bodies and structures intermediate between the two. In addition, the profiles contained large amounts of glycogen and small numbers of vesicles. These nerve fibres were classified as baroreceptors, since they closely resemble carotid sinus and aortic arch baroreceptors in mammals. Large numbers of chromaffin cells were found, particularly in the common wall of the pulmonary and left aortic arteries. Many of these cells emitted a long tapering process, which sometimes entered a nearby nerve bundle. Sensory, p-type and c-type profiles, but not adrenergic profiles, made extensive close contacts with chromaffin cells.

Dissection of stages in exocytosis in the adrenal chromaffin cell with use of trifluoperazine

Stimulation of isolated chromaffin cells with carbamylcholine led to a number of morphological changes, indicative of exocytosis, apparently resulting from translocation of secretory granules to the plasma membrane and their subsequent fusion with the plasma membrane to release their contents. However, stimulation in the presence of trifluoperazine resulted only in the accumulation of secretory granules close to the plasma membrane. Thus exocytosis could be divided into two stages: a trifluoperazine-insensitive stage involving translocation of secretory granules to the plasma membrane and a second trifluoperazine-sensitive stage resulting in granule-plasma membrane fusion.

Adrenaline-, noradrenaline- and small granule- containing cells in the adrenal gland of Discoglossus pictus (Amphibia, Anura)

In the adrenal gland of Discoglossus pictus, various types of chromaffin cells are described: noradrenaline cells, adrenaline cells and small granule-containing cells (on the basis of electron density and shape of the granules). The chromaffin cells occur in small groups, and have cytoplasmic processes which may surround them in the form of parallel layers. Their nerve supply is sparse. The possible function of SGC-cells, in relation to those described in other vertebrates, is discussed.

Long-term effects of dexamethasone and nerve growth factor on adrenal medullary cells cultured from young adult rats

Normal postnatal rat chromaffin cells and rat pheochromocytoma cells are known to show extensive Nerve Growth Factor (NGF)-induced process outgrowth in culture, and this outgrowth from the postnatal chromaffin cells is abolished by the corticosteroid dexamethasone. To determine whether adult rat chromaffin cells respond to NGF and dexamethasone, dissociated adrenal medullary cells from 3-month-old rats were cultured for 30 days in the presence or absence of these agents. Such cultures contained typical chromaffin cells, chromaffin cells with processes, and neurons. Fewer than 2% of normal adult chromaffin cells formed processes under any of the conditions studied, and statistically significant changes in this proportion were not detectable in the presence of NGF or dexamethasone. Adrenal medullary neurons, however, were observed only in the presence of NGF, in cultures with or without dexamethasone, and thus appear to be previously unreported NGF targets which require NGF for survival or process outgrowth. Dexamethasone markedly increased total catecholamine content, total content of epinephrine, and tyrosine hydroxylase activity in cultures with or without NGF. In contrast, postnatal rat chromaffin and rat pheochromocytoma cells which have been studied in culture do not produce epinephrine under any of these conditions. It is concluded that rat adrenal chromaffin cells undergo age-related changes in both structural and functional plasticity. The in vitro characteristics of rat pheochromocytoma cells more closely resemble those of postnatal than of adult rat chromaffin cells, but may not entirely reflect the properties of the majority of chromaffin cells in either age group.

Catecholamine transport and energy-linked function of chromafffin granules isolated from a human pheochromocytoma

The structure and function of chromaffin granules of human pheochromocytoma was extensively investigated in a highly purified granule fraction obtained from a single specimen of human pheochromocytoma tissue. Pheochromocytoma chromaffin granules were analyzed for catecholamine, ATP, enkephalin, phospholipid, cytochrome and ion content. Using a variety of techniques it was found that the membrane of these granules is highly impermeable to Na+, K+, and H+, and that the intragranular pH was maintained at 5.1 irrespective of suspending media. The presence of MgATP induces a transmembrane potential (delta psi) across the membrane of these granules which is positive inside and which corresponds to 90 mV. Both delta pH and delta psi are coupled to biogenic amine accumulation into the granules in a process which is reserpine sensitive. These properties are compared with those of chromaffin granules isolated from normal human tissue or from other animal species and are discussed in terms of possible explanation at a biochemical or subcellular level of the clinical manifestation of the pheochromocytoma.

Adrenal chromaffin granules: evidence for an ultrastructural equivalent of the proton-pumping ATPase

Adrenal chromaffin granules are known to possess an F1-ATPase which according to biochemical criteria is very similar to the mitochondrial one. To find a morphological equivalent for this enzyme chromaffin granules from bovine adrenal medullar were subjected to negative staining and freeze-etching. With both methods globular particles of 8 to 9 min diameter could be demonstrated on the surface of these organelles. A single granule possessed on average 22 particles. In negative staining the particles appeared separated from the membrane by a stalk of 8 nm. This typical morphological appearance was independent from a great variety of experimental procedures. After freeze-etching the particles were closely apposed to the membrane without any evidence for an interposed stalk. Pretreatment of chromaffin granules with pronase or trypsin led to a time dependent disappearance of the surface particles. In negative staining the stalked of chromaffin granules were found to be very similar in structure and size to those of mitochondria which have already been identified as F1-complexes. Based on this observation and other lines of evidence we suggest that the stalk particles found on the surface of chromaffin granules represent the F1-complex of the proton-pumping ATPase of these organelles.

Characterization of catecholamine-storage organelles in transplantable phaeochromocytoma and adrenal glands of rats

The properties of the catecholamine-storing organelles from transplantable rat phaeochromocytoma and rat adrenal glands were compared by density gradient centrifugation. It was shown that tumour granules are more heterogeneous and less dense than adrenal granules. Both granule preparations can take up catecholamines and nucleotides by a process driven by an electrochemical proton gradient. Dopamine beta-hydroxylase and glycoprotein III were analysed by immunological techniques. Glycoprotein III was shown to be a specific component of chromaffin granules. Tumour tissue (average weight 700 mg) contains amounts of these antigens comparable to those in 210 adrenals. The biosynthesis of granules in the tumour apparently occurs at a low rate, making turnover studies difficult. The transplantable rat phaeochromocytoma is very useful for studies on the uptake properties and the immunological characteristics of rat catecholamine storage granules because on tumour provides an amount of material that could otherwise be obtained only from a large number of adrenal glands.

Core structure, internal osmotic pressure and irreversible structural changes of chromaffin granules during osmometer behaviour

In the adrenal medullary cells, catecholamines are stored in and secreted from specialized secretory vesicles, the chromaffin granules. In order to gain some understanding of both functions of chromaffin granules, it is important to characterize their biophysical organization. Using isolated bovine chromaffin granules we have investigated the osmometer behaviour of chromaffin granules by 31P-NMR and fluorescence spectroscopy, by turbidity measurements and by electron-microscopic determination of chromaffin granule size distributions. On the basis of the osmometer model we have formulated equations predicting the behaviour of the native catecholamine fluorescence quenching and of the size of chromaffin granules a a function of osmolarity and have shown experimentally that the granules' behaviour conforms to these. It was possible to estimate the osmotic activity of the chromaffin granule core solution and the mean absolute water space in chromaffin granules from the determination of the size distributions as a function of osmotic pressure. With NMR spectroscopy a selective line-broadening of the alpha-resonances was observed with increasing osmolarities, while the gamma-phosphorus resonances remained virtually unchanged. Possibly there is an increase in core viscosity with osmolarity which affects only the alpha- and beta-phosphorus groups. While suspending chromaffin granules from lower to higher osmolarities causes no lysis, moving them back to their original osmolarity at which they were previously stable lyses them, thereby releasing a maximum of 70% of their releasable protein. This 'hyperosmolar' lysis is independent of preincubation times in the higher osmolarities and of the absolute dilution applied but depends on dilution beyond the 405 to 322 mosM sucrose range. Under the experiment conditions no uptake of sucrose from the medium into the granules could be measured, thereby suggesting that hyperosmolar lysis is a phenomenon not due to solute penetration. Since with NMR and fluorescence spectroscopy no chemical changes in the core composition can be observed, we conclude that hyperosmolar lysis may be caused by irreversible membrane relaxation upon osmotic shrinking.

Human catecholamine storage vesicle proteins

Catecholamines in the adrenal medulla and sympathetic nerve are stored in vesicles, along with numerous proteins and peptides; both catecholamines and proteins are released by and are markers of exocytosis during sympathoadrenal neurosecretion. The proteins include the enzyme dopamine-beta-hydroxylase and the chromogranins, a group of molecules of largely undetermined function. We have isolated catecholamine storage vesicles (chromaffin granules) from bovine adrenal medulla and human pheochromocytoma. The numerous soluble proteins in the granules: (a) have a spectrum of sizes; (b) have a spectrum of charges; and (c) display considerable interspecies qualitative homology. Dopamine-beta-hydroxylase (DBH) was isolated from human and bovine vesicles by Concanaval in A affinity chromotography. DBH is a tetrameric glycoprotein consisting of 2 non-covalently joined dimeric subunits, each of which is 2 disulfide linked monomers; interspecies molecular weight differences were noted. Ongoing studies concern chromogranin A, the quantitatively major vesicle protein, in bovine and human vesicles.

In vitro reconstitution of chromaffin granule-cytoskeleton interactions: ionic factors influencing the association of F-actin with purified chromaffin granule membranes

Chromaffin granules are the secretory vesicles directly involved in exocytosis of catecholamines, enkephalins, and other components from adrenal medullary cells. The granules occupy a large portion of the cytoplasmic volume and thus may interact extensively with cytoskeletal elements such as actin. Indeed, using both sedimentation techniques and falling ball viscometry [Fowler et al: J Cell Biol 88: 388, 1981] to measure actin binding by membranes, we were able to show that chromaffin granules bind F-actin via a protein site on the membrane, and that these interactions are reversibly inhibited by raising the free calcium ion concentration to micromolar levels ([Ca++]free for half-maximal inhibition approximately 2.6 x 10(-7)M)[Fowler and Pollard: Nature 295:336, 1982]. Here, we show that F-actin-chromaffin granule interactions are unaffected by changes in pH between about pH 6.4 and 7.4 but are about 50% inhibited by raising the pH from 7.5 to 8.0. They are also 50% inhibited by increasing the KCl concentration to about 200 mM but are not significantly affected by increasing concentrations of K-glutamate up to 500 mM or by varying the MgCl2 concentration between 0 and 6 mM. The interactions between chromaffin granule membranes and F-actin are also reduced in the presence of ATP, AMP-PNP, or free pyrophosphate; cAMP and AMP are without effect. The ability of chromaffin granule membranes to interact with F-actin under conditions that may approximate the resting intracellular environment (neutral pH, low KCl, 1-2 mM MgCl2, 1 mM ATP, [Ca++]free less than 10(-7)M, 30 degrees C) suggests that these interactions may partially reconstitute naturally occurring associations between chromaffin granules and the cytoskeleton. Further, regulation of chromaffin granule membrane-actin interactions by ionic factors (pH, calcium, chloride ions, nucleotides) that vary intracellularly leads us to propose that associations between actin and the chromaffin granule membrane could influence the location and dislocation of these organelles in the cytoplasm.

A phase-contrast and immunofluorescence study of adrenal medullary chromaffin cells in culture: neurite formation, actin and chromaffin granule distribution

Immunofluorescence studies of bovine chromaffin cells in culture with specific antibodies against dopamine-beta-hydroxylase gave a distinct punctate pattern of labelling, reflecting the distribution of chromaffin granules. There was strong staining of cell extensions and growth ones. Linear arrays of fluorescent dots were observed, suggesting an association of granules with a filamentous cytoskeleton. Labelling of neuritic processes was periodic, perhaps indicative of a packaging of secretory granules. Chromaffin cells stained strongly with specific anti-actin antisera. Fine filament bundles were observed, and also diffuse staining, some punctate labelling and staining of the plasma membrane or sub-membranous cytoplasm. Growth cones and non-terminal cytoplasmic varicosities contained significant amounts of actin. Colchicine (5 X 10(-5) M) caused retraction of neuritic extensions and formation of lateral growth cones. Cytochalasin (10 microgram/ml) caused ballooning of terminal growth cones and non-terminal cytoplasmic varicosities. Phalloidin (10(-4) M) stimulated microspike formation. The results are discussed in terms of the role of the cytoskeleton in growth cone formation, cell-substratum contacts and the transport of chromaffin granules.

An electron microscopic study of the cardiac innervation in larval lamprey

Larval lampreys (Lampetra japonica) 13 and 21 mm in body length were examined by serial section electron microscopy and it was found that the young 13-mm larvae which was 26 days old had no nerves to, and in, the heart. However, the heart of 21-mm larval lampreys had two sets of nerve fibers entering the heart. One of the nerve fibers entered the heart via the porta venosa, ran along the vena jugularis impar, and ended in the sinus venosus. The other nerve entered with the porta arteriosa and terminated in the proximal region of the bulbus cordis. Two characteristic types of nerve endings were observed. One type of nerve ending contained numerous, small, clear vesicles about 40 nm in diameter. These endings were found only in the walls of the vena jugularis impar and the sinus venosus. The second type of ending characteristically contained distinctive large-cored vesicles 60-130 nm in diameter mixed with numerous small, clear vesicles. These endings were present in the walls of the vena jugularis impar, the sinus venosus, and the bulbus cordis. It should be emphasized that the bulbus contained only the second type of nerve ending. The nerves in the heart were confined to specific regions and those from the two sources remained separate. Furthermore, the atrium, ventricle, ducts of Cuvier, and hepatic veins were completely devoid of nerves. There were no ganglion cells in any region of the heart.

Unusual cytoplasmic bodies in chromaffin cells of the adrenal medulla of the viscacha (Lagostomus maximus maximus)

Complex structures can be seen associated with large areas of endoplasmic reticulum of the chromaffin cells in the viscacha adrenal medulla. These structures are cylindrical in shape and are formed by chains of globular subunits. A central lumen is observed within which there are bodies resembling chromaffin granules. Parallel cisternae of the endoplasmic reticulum are arranged surrounding these bodies. The functional significance of these structures in unknown.

The distribution of Mg2+ ATPase and its loss of specific activity upon gradient centrifugation of isolated chromaffin granules

Preparations of purified chromaffin granules were subjected to isopycnic sucrose gradient centrifugation. Determination of Mg2+ ATPase activity and catecholamines showed that the distribution of ATPase almost parallelled the distribution of catecholamines. The distribution of ATPase was slightly shifted to lower densities and was suggested to be caused by the heterogeneity of the chromaffin granules. The results therefore provide evidence that ATPase is associated with chromaffin granules. Determination of the recovery of ATPase activity upon gradient centrifugation revealed losses of enzyme activity which were found to be proportional to the dilutions of the granule preparation subjected to gradient centrifugation.

Giant granules in adrenaline-secreting chromaffin cells of lizard adrenal glands after metyrapone administration

Secretory granules of extraordinary size, some of them bigger than the cell nucleus, abound in the adrenaline cells of lizard adrenals after metyrapone injections during 7 days. In these granules, the bounding membrane is studded with ribosomes, and the core is formed by rounded small subunits. Some granules of this type are also found in noradrenaline cells. They may represent an exceptionally increased elaboration and storage of adrenaline, induced by metyrapone probably through its action on steroidogenic tissue.

Do enterochromaffin (EC) cells contain motilin?

Identity of motilin-immunoreactive cells (motilin cells) and enterochromaffin (EC) cells was investigated. Human and dog gastro-entero-pancreatic tissues were examined using conventional stain technologies, indirect immunofluorescence and immunoperoxidase methods and electron microscopy. Enterochromaffin cells were identified by Masson-Hamperl's silver impregnation method. Results obtained were summarized as follows. 1. Motilin-immunoreactive cells were dispersed in the epithelium of the small intestine with a vague tendency to be concentrated in the deeper portion of the crypt. They were most frequent in the duodenal and jejunal mucosa; a few of them were also seen in the ileal mucosa. No motilin cells were found in the stomach, colon, rectum and pancreas. 2. In contrast, enterochromaffin cells were found in the stomach and pancreas as well as in the whole intestine. 3. Observation of the same or adjacent sections after immunofluorescence and argentaffin reaction demonstrated that motilin-reactive cells were non-argentaffin. Different techniques, including immunoperoxidase method at the electron microscope level, indicated that the enterochromaffin cells were totally different from the cells which contained motilin. 4. In the human fetus (16 to 24-week-old), Segi's cap, i.e., aggregated basal-granulated cells on the top of the villus discovered by Segi (1935), was seen in the duodenum and upper jejunum. The majority of basal-granulated cells forming this body were argyrophil, 30-50% of them were argentaffin (i.e., enterochromaffin), and less than 10% of them were motilin-immunoreactive.

Organisation of the proteins of the chromaffin granule membrane

The organisation of the protein components of bovine chromaffin granules has been investigated by labelling or digesting intact granules or broken membranes with the following reagents: lactoperoxidase/Na125I as a reagent for tyrosine residues, N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulphonic acid as a reagent for cysteine residues, pronase, and galactose oxidase/KB3H4. Following treatment, membranes were purified and washed and proteins were examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. Rather more than 60 bands were resoved, of which about 40 were relatively intense and reproducible. The bands were classified according to their molecular weights and sensitivity to reagents. Penetration of the membranes by the reagents was assessed by examination of intragranular porteins. The majority of chromaffin granule membrane polypeptides became labelled when intact granules were treated with impermeant reagents. Eleven were probably protected in the intact granules, reactive sites becoming exposed only on membrane lysis. By contrast, carbohydrate moieties of glycoproteins appear to be exposed only on the matrix side of the membrane. Two proteins were shown to span the membrane, although this is probably an underestimate.

Ultrastructural demonstration of Mg-ATPase activity of the chromaffin granule

Histochemical evidence for magnesium-activated-ATPase activity of chromaffin granules in the hamster adrenal medulla is presented. A modified Wachstein-Meisel medium, using 40 mM magnesium, was employed. Not all chromaffin granules were reactive, but the reaction product was more noticable on noradrenaline granules than adrenaline granules. Presumtive exocytotic sites were very reactive. Small vesicles, elongated-granules, lysosomes, the plasma membrane, the endoplasmic reticulum, and mitochondria were also reactive.

Comparison of the ultrastructure of adrenaline and noradrenaline storage granules of bovine adrenal medulla

The ultrastructure of the membranes of noradrenaline (NA) and adrenaline (A) granules of the bovine adrenal medulla (Terland, O., T. Flatmark, and H. Kryvi, Biochim, Biophys. Acta 553, 460--468 (1979)) was analyzed by transmission, negative staining and freeze-etch electron microscopy. The two types of storage granules can be distinguished mainly by two morphological criteria: (a) The NA-granules have a more electron dense matrix core than the A-granules, (b) the NA-granules revealed less asymmetry in the distribution of intramembrane particles (nPF:nEF = 4,5:1) than the A-granules (nPF:nEF = 9:1). Thus, the trilaminar structure, negative staining pattern and size distribution of the intramembrane particles of the two fracture faces on freeze-etch electron microscopy were very similar for the two types of granules. Freeze-etching revealed a wide range of the particle size distribution for both fracture faces in both types of granules, with an average diameter of 12.6 +/- 2.7 nm (A-granules) and 10.2 +/- 2.8 nm (NA-granules) for the E-fracture faces and 11.4 +/- 2.7 nm (A-granules) and 9.8 +/- 2.4 nm (NA-granules) for the P-fracture faces. Some of the particles on the P-fracture face (outer surface of the membrane) revealed a subunit structure, most clearly seen in the specimens of NA-granules. Morhpometric analyses of sectioned bovine adrenal medulla revealed that the chromaffin granules on an average account for approx. 13.5% of the cytoplasmic volume in the total population of chromaffin cells.

Stress-induced degranulation accompanied by vesicle formation in the adrenal chromaffin cells of the mouse

Stress was induced in mice by restraining on a board by pinning their limbs followed by immersion of the hind feet in a water bath of 20 degrees C. Fine structure of adrenal chromaffin cells was studied by light and electron microscopy. After 8 to 22 hrs' stress, remarkable decrease in the number of argentaffin granules of the NA cells was demonstrated by light microscopy. By electron microscopy, the decline in the granule number was marked in A, NA and SGC cells. This degranulation was accompanied by theoccurrence of numerous smally cytoplasmic vesicles which often appeared empty but sometimes contained an electron-dense material. Granule-containing invaginations of plasma membrane were frequently seen and were interpreted to represent the exocytotis profiles. The idea that the secretory granule membrane and associated substances might be recovered in the form of cytoplasmic vesicles was thus supported. Exposure of the mouse to restraint plus water immersion stress proved to be a simple method for production of acute and drastic degranulation of the adrenal chromaffin cells.

Cytochemical studies on cytoplasmic granular elements in the hamster pineal gland

The pineal gland of adult golden hamsters (Mesocricetus auratus) was studied by various cytochemical methods at the electron microscopic level: (1) the modified chromaffin reaction specific for 5-hydroxytryptamine (5-HT), (2) argentaffin reaction, (3) zinc-iodide-osmium (ZIO) mixture reaction and (4) acid phosphatase reaction. In the pinealocytes, the dense-cored vesicles (80-160 nm in diameter) show both chromaffinity and argentaffinity, while the population of dense bodies (150-400 nm in diameter) is reactive to ammoniacal silver solution and ZIO mixture but not to the modified chromaffin reaction. After incubation for demonstration of acid phosphatase activity, reaction products are localized in some, but not all, of the dense bodies, in some of the small vesicles in the Golgi region and in one or two inner Golgi saccules. In nerve fibers in the pineal gland, small granulated vesicles are also reactive to the modified chromaffin reaction and ZIO mixture. Based upon these cytochemical results the following conclusions have been reached: (1) dense cored vesicles in the pinealocytes and small granulated vesicles in the nerve fibers of the hamster pineal gland contain 5-HT, and (2) the population of dense bodies in the pinealocytes is heterogeneous, some are lysosomes and the other are possibly the granules responsible for the secretion of pineal peptides.

Differential scanning calorimetry of chromaffin granule membranes

Differential scanning calorimetry thermograms of native chromaffin granule membranes exhibit several peaks in the 15-35 degrees C region. Extraction of cholesterol increases the size of the melting peaks. Addition of Ca2+ ions does not seem to influence the lipid transitions.

Isolation and characterization of noradrenalin storage granules of bovine adrenal medulla

A method is described for the preparation of (1) the heavy population of bovine adrenal chromaffin granules (SH (average sedimentation coefficient) = 12 400 S in 0.25 M sucrose) essentially free from contamination with mitochondria and other organelles, and (2) a subpopulation of this heavy population which is highly enriched in noradrenalin (greater than or approximately 95% of the total catecholamine is noradrenalin). The method is based on isopycnic gradient centrifugation using a self-generating gradient of polyvinylpyrrolidone-coated colloidal silica particles (Percoll) in 0.5 M sucrose medium. The isolated population of noradrenalin granules appeared highly electron dense in transmission electron microscopy and revealed a rather narrow size distribution. The specific content of amine and adenine nucleotides (with reference to total granule protein) was markedly higher than for the total population of heavy chromaffin granules. The molar ratio of amines to adenine nucleotides was, however, lower in the noradrenalin granules, i.e. 4.8 vs. 11.9.

Light scattering turbidity changes as a measure of the kinetics of Ca2+ -promoted aggregation of chromaffin granule membrane ghosts

Changes in turbidity seen when chromaffin granule membrane ghosts are aggregated by Ca2+ can be modelled as dimerization of hollow spheres using Rayleigh-Gans-Debye light-scattering theory. The experimental changes agree well with the calculations. Thus, if shape or refractive index changes produced by osmotic perturbation, ion uptake, etc. can be excluded, turbidity readings can be used to follow the progress of the aggregation reaction of storage vesicles and other small particles or macromolecules.

Freeze-fracture study of the chromaffin cell during exocytosis: evidence for connections between the plasma membrane and secretory granules and for movements of plasma membrane-associated particles

Exocytosis was studied in acetylcholine-stimulated bovine adrenal medulla. During a pre-exocytotic stage, chromaffin granules are found in juxtaposition to the plasma membrane and separated from it by an electron dense space 25--27 A in width. Freeze-fracture studies show this stage to be characterized by connections between the granules and the plasma membrane. These connections are apparently cytoplasmic but bridge both membranes; they are presumably proteinaceous, but their exact nature remains to be elucidated. Later stages of exocytosis were also studied by the freeze-fracture technique; a typical feature is the lack of intramembrane particles around the fusion site. Both connections and membrane particle movement are discussed in terms of recent biochemical findings.

Divalent cation-induced aggregation of chromaffin granule membranes

Divalent cations induce the aggregation of chromaffin granule ghosts (CG membranes) at millimolar concentrations. Monovalent cations produce the same effect at 100-fold higher concentrations. The kinetics of the dimerization phase were followed by light-scattering changes observed in stopped-flow rapid mixing experiments. The rate constant for Ca2+-induced dimerization (kapp) is 0.86-1.0 x 10(9) M-1sec-1, based on the "molar" vesicle concentration. This value is close to the values predicted by theory for the case of diffusion-controlled reaction (7.02 x 10(9) M-1sec-1), indicating that there is no energy barrier to dimerization. Arrhenius plots between 10 degrees and 42 degrees C support this; the activation energy observed, +4.4 Kcal, is close to the value (4.6-4.8 Kcal) predicted for diffusion control according to theory. Artificial vesicles prepared from CG lipids were also found to have cation-induced aggregation, but the rates (values of kapp) were less than 1/100 as large as those with native CG membranes. Also, significant differences were found with respect to cation specificity. It is concluded that the slow rates are due to the low probability that the segments of membrane which approach will be matched in polar head group composition and disposition. Thus large numbers of approaches are necessary before matched segments come into aposition. The salient features of the chromaffin granule membrane aggregation mechanism are as follows: (a) In the absence of cations capable of shielding and binding, the membranes are held apart by electrostatic repulsion of their negatively charged surfaces. (b) The divalent and monovalent cation effects on aggregation are due to their ability to shield these charges, allowing a closer approach of the membrane surfaces. (c) The major determinants of the aggregation rates of CG membranes are proteins which protrude from the (phospholipid) surface of the membrane and serve as points of primary contact. Transmembrane contact between these proteins does not require full neutralization of the surface charge and surface potential arising from the negatively charged phospholipids. (d) After contact between proteins is established, the interaction between membranes can be strengthened through transmembrane hydrogen bonding of phosphatidyl ethanolamine polar head groups, divalent cation-mediated salt bridging, and segregation of phosphatidylcholine out of the region of contact.

Particle segregation in chromaffin granule membranes by forced physical contact

Bovine chromaffin granules were exposed to different isotonic non-ionic and ionic solutions (sucrose; Ca2+- and Mg2+-free phosphate-buffered saline; Tris-HCl + NaCl; Ca2+- and Mg2+-free phosphate-buffered saline + sucrose; Tris-HCl + sucrose) at pH 7 and then frozen either in suspension or as firm pellets. Freezing was performed without prefixation or antifreeze treatments either by 'standard' techniques (approx. 1 mm3 suspended or pelleted material on gold specimen supports dipped into liquid Freon) or with increased cooling rates by spraying suspensions into liquid propane ('spray-freezing'). Regardless of the freezing method, membrane-intercalated particles were always randomly distributed when chromaffin granules were frozen in suspension. In contrast, forced physical contact between granules produced by centrifugation (12000 X g, 25 min) provoked dispersal of membrane-intercalated particles, but only in the presence of ions. Sucrose or EDTA in an ionic environment had no inhibitory effect. The following conclusions are derived: (1) Even below the reported phase transition region particle clustering is possible. (2) Chromaffin granule membranes are not liable to thermotropic segregation of membrane-intercalated particles. (3) Although the low freezing rates of 'standard' freezing techniques produce large-scale segregation artefacts (by which suspended chromaffin granules are pushed together within the segregated solute) this does not result in intramembraneous particle segregation. (4) Forced physical contact produces a Ca2+-independent particle segregation, but only when repulsive electrostatic forces of membrane components are partially screened in an ionic environment. (5) This does not invalidate results obtained by others, showing Ca2+-mediated chromaffin granules agglomeration and segregation of membrane-intercalated particles, but it might indicate the occurrence of another, not directly Ca2+-dependent particle segregation mechanism in a prefusional stage of close membrane-to-membrane contact during exocytosis.

Ultrastructural radioautography of the incorporation of tritiated leucine by the rat adrenal medulla in vivo

Sections of tissues from the adrenal medullae of young rats were subjected to radioautography after a single intravenous injection of L-leucine 4, 5(3)H to identify the sites of synthesis and follow the migration of newly-formed proteins in both adrenaline-storing (A) and noradrenaline-storing (N) cells. As early as 2 min after injection of leucine 3H, the label was highest in the rough endoplasmic reticulum (RER) of A and N cells, suggesting that cisternal ribosomes are sites of protein synthesis. By 5 and 10 min, much of the label had migrated from the RER into the Golgi complex of both cell types. Some label was already present over the secretory granule matrix (chromogranins) by 2 min but the peak was reached at 1 h in both A and N cells. By 4 h, the label over the secretory granules had diminished, indicating a release of newly-synthetized chromogranins outside the cells. The label over the hyaloplasm was relatively high at 2 min but it decreased rapidly to low levels. In contrast, the label over the cell surface continually increased to reach the highest levels among all organelles at 4 h in both cell types. The pattern of increment of the label over the cell surface suggests that the newly-formed proteins of these sites are also synthetized in the RER, pass through the Golgi complex and are transported in the hyaloplasm, before reaching the surface of A and N cells.

[2 cases of sympathetic paraganglioma of the urinary bladder]

Two cases of symphathetic paraganglioma of the urinary bladder are reported. Symppathetic- or parasymphatetic origin of intramural paraganlia or paragangliomas can be determined by demonstration of praesynaptic myelinated fibers. This method gives more reliable results than formaldehyd-induction-method carried out on freezed sections or the Gömöri's chromaffin reaction which often appears to be false-negative.