A novel effect of cobalt treatment on calcium-dependent responses of the cockroach salivary gland

Summary After incubation in calcium-free solutions containing cobalt, the readmission of calcium caused prolonged but reversible hyperpolarization of acinar cells of cockroach salivary glands and prolonged fluid secretion. It is suggested that cobalt treatment increases the permeability of the acinar cell membrane to calcium.Acknowledgments. We are indebted to the Medical Research Council for support.     

Demilune cells of the cat submandibular gland; an unlikely source of kallikrein

The functional significance of kallikrein in the salivary gland remains unclear partially because of uncertainty over its precise cellular localization. Kallikrein was thought to originate in acinar cells, until recent evidence from cat and rat localized it primarily to the ducts. The possibility that salivary kallikrein may also be located in demilune cells was investigated in this study. - The total kallikrein content of cat submandibular glands was found to be substantially reduced by sampathetic nerve stimulation; whereas parasympathetic stimulation had no significant effect. These biochemical findings did not correlate with morphological studies that revealed almost complete depletion of the demilune cells secretory granules after stimulation of either division of the autonomic nerve supply. This lack of correlation makes it unlikely that kallikrein is present in the demilune cell secretory granules.     

Exocrine pancreas: difference in the amylase content of the dorsal and ventral regions

Summary The amylase content of the acinar tissue is higher in the splenic region of the rat pancreas containing glucagon-rich islets than in the duodenal region harboring pancreatic polypeptide-rich islets.This work was supported by a grant from the Belgian Ministry of Scientific Policy.     

Demilune cells of the cat submandibular gland; an unlikely source of kallikrein

Summary The functional significance of kallikrein in the salivary gland remains unclear partially because of uncertainty over its precise cellular localization. Kallikrein was thought to originate in acinar cells, until recent evidence from cat and rat localized it primarily to the ducts. The possibility that salivary kallikrein may also be located in demilune cells was investigated in this study. — The total kallikrein content of cat submandibular glands was found to be substantially reduced by sampathetic nerve stimulation; whereas parasympathetic stimulation had no significant effect. These biochemical findings did not correlate with morphological studies that revealed almost complete depletion of the demilune cells secretory granules after stimulation of either division of the autonomic nerve supply. This lack of correlation makes it unlikely that kallikrein is present in the demilune cell secretory granules.Acknowledgment. This study is made possible through the Dean's MRC grant number MD-3489 to the College of Dentistry, University of Saskatchewan.Authors wish to thank Mr. D. Duncan, Dept. of Oral Biology and D. Mandeville of Medical Photographic Services for technical assistance.     

Role of salivary glands in the maintenance of midgut amylase activity inPeriplaneta americana L.

Summary It was experimentally demonstrated, by the surgical removal of salivary glands and severence of salivary ducts, that most of the amylase in the gut ofPeriplaneta americana comes from the salivary glands.We wish to acknowledge Prof. H. Swarup (Jiwaji University, Gwalior, M.P.) for working facilities provided at School of Studies in Zoology, Vikram University, Ujjain, M.P., and Council of Scientific and Industrial Research, New Delhi, for fincancial support in the form of Junior Research Fellowship to one of us (O.P.A.)     

The role of kinesin, dynein and microtubules in pancreatic secretion

The regulated secretion of pancreatic zymogens depends on a functional cytoskeleton and intracellular vesicle transport. To study the dynamics of tubulin and its motor proteins dynein and kinesin during secretion in pancreatic acinar cells, we infused rats with 0.1 μg/kg/h caerulein. Electron and fluorescence microscopy detected neither dynein nor kinesin at the apical secretory pole, nor on the surface of mature zymogen granules. After 30 min of secretagogue stimulation, kinesin and the Golgi marker protein 58 K were reallocated towards the apical plasma membrane and association of kinesin with tubulin was enhanced. Disruption of acinar cell microtubules had no effect on initial caerulein-induced amylase release but completely blocked secretion during a second stimulus. Our results suggest that mature zymogen granule exocytosis is independent of intact microtubules, kinesin and dynein. However, microtubule-dependent mechanisms seem to be important for the replenishment of secretory vesicles by redistribution of Golgi elements towards the apical cell pole. J. Schnekenburger and I.-A. Weber have contributed equally to this work.     

The effect of a phorbol ester upon the cholinergic regulation of potassium permeability in the rat submandibular gland

Acetylcholine releases calcium from cytoplasmic stores and permits an influx of calcium in salivary acinar cells. The resultant rise in [Ca²⁺]_i causes an increase in potassium permeability which is an important part of the secretory response. We have investigated the effects of 12-0-tetradecanoyl phorbol-13-acetate, a potent activator of protein kinase C, upon this regulation of potassium permeability in superfused pieces of rat submandibular salivary gland. This compound inhibited the initial [Ca²⁺]_o-independent component of the response of acetylcholine but had no effect upon the subsequent [Ca²⁺]_o-dependent phase. This compound does not, therefore, appear to inhibit receptor-regulated calcium influx.     

Thermal acclimatory responses of salivary amylase of Periplaneta americana (Linn.)

Summary A differential thermal acclimatory response of salivary amylase is evident in P. americana-nymphs demonstrating a translational and males a rotational pattern, while females exhibit the translational cum rotational pattern (Prosser's type IV-D).     

Anionic activation of human salivary amylase.

In all earlier studies on alpha-amylase, the influence of different ions were studied in phosphate buffer. The present report shows the effect of different ions individually with Tris and amino acid. Though it has been claimed recently that sodium ion is an activator of alpha-amylase, this study reconfirms that sodium ion does not activate human salivary amylase.     

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

3H-thymidine autoradiography showed an enhanced DNA synthesis in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.     

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

Summary ³H-thymidine autoradiography showed an enhanced DNA synthesis, in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.This work is supported by NIH grant CA 36043.     

The islet-acinar axis of the pancreas: Is there a role for glucagon or a glucagon-like peptide?

Intravenous glucagon inhibits exocrine pancreatic secretion in vivo, but exogenous glucagon does not affect exocrine secretion in vitro. Recent work, however, suggested that endogenous glucagon may be involved in the regulation of exocrine secretion even in vitro. We therefore investigated the effects of exogenous and endogenous glucagon on exocrine secretion by the isolated perfused rat pancreas in the presence of 1.8 mM glucose. Exogenous glucagon did not affect CCK-stimulated amylase output. 20 mM arginine stimulated glucagon release, but did not affect basal enzyme secretion. CCK-stimulated amylase output, however, was significantly inhibited in the presence of arginine. This inhibitory effect of arginine on exocrine pancreatic secretion could be blocked by glucagon antibodies, but not by nonspecific gammaglobulins. Thus exogenous glucagon failed to affect exocrine pancreatic secretion in vitro, but endogenously released glucagon or a glucagon-like peptide inhibited amylase release in the isolated perfused pancreas. We conclude that glucagon or a glucagon-like peptide may be a mediator in the islet-acinar axis.     

Cells secreting antibodies originate from cells secreting immunoglobulins without a detectable antibody function for the antigen injected]

Cells secreting immunoglobulins without detectable antibody function arising after an injection of horseradish peroxidase were micromanipulated from the center of haemolytic plaques of Sheep red blood cells coated with anti-Ig antibodies. These cells were cultured individually for 48 hrs, with irradiated cells as feeder layer and in the presence of the immunogen and of LPS. It was shown that after this time 22% of the immunoglobulin-secreting cells had generated antiperoxidase antibody-secreting cells or were transformed into antibody-secreting cells.     

A new biological activity for the neuropeptide FMRFamide: experimental evidence for a secretagogue effect on amylase secretion in the scallopPecten maximus

FMR Famide immunoreactivity in the digestive tract of the bivalve molluscPecten maximus was investigated by immunocytochemistry. Positive FMRFamide-like immunoreactivity was detected in nerve fibres in close contact with exocrine α amylase secreting cells. Physiological studies on enzymatically dissociated cells of the stomach-digestive gland complex demonstrated the involvement of FMR Famide and analogues in the control of α amylase release from the cells. The FMRF Famide-induced secretion was shown to be time- and dose-dependent. In contrast to most naturally occurring vertebrate secretagogues which are hormones, FMRFamide appears to work in our in vitro system as a paracrine factor.     

Fine structrual relation between pancreatic excretory ductules and intercellular spaces.

Horse-radish peroxidase injected into the femoral vein of intact rats, or infused at 30 cm H2o pressure into the main pancreatic duct of intact dogs, entered easily the interstitial spaces surrounding acini and acinar cells. The latter are interconnected at their luminal segments by zonulae occuldentes. These junctions form a barrier to tracer penetrating from the interstituim towards the lumen of terminal ductules. However, the intraductally infused peroxidase entered the interstitial spaces, probably through the pressure injured acinar cells, as did colloidal carbon particles when infused intraductally.     

Genesis of concentric laminated inclusions in the nucleus

Summary Single-membrane-bound inclusions containing zymogen granules were found in pancreatic acinar cells. Images were seen suggesting that the concentric laminated inclusion is derived by hydration and fusion of such granules within the inclusion.     

Genesis of concentric laminated inclusions in the nucleus

Single-membrane-bound inclusions containing zymogen granules were found in pancreatic acinar cells. Images were seen suggesting that the concentric laminated inclusion is derived by hydration and fusion of such granules within the inclusion.     

Fine structural relation between pancreatic excretory ductules and intercellular spaces

Summary Horse-radish peroxidase injected into the femoral vein of intact rats, or infused at 30 cm H₂O pressure into the main pancreatic duct of intact dogs, entered easily the interstitial spaces surrounding acini and acinar cells. The latter are interconnected at their luminal segments by zonulae occludentes. These junctions form a barrier to tracer penetrating from the interstitium towards the lumen of terminal ductules. However, the intraductally infused peroxidase entered the interstitial spaces, probably through the pressure injured acinar cells, as did colloidal carbon particles when infused intraductally.     

Pathological changes in the heterologous phase of antibasement membrane antibody mediated disease in the rat

Summary The immunological and structural changes during the heterologous phase of experimental antibasement membrane antibody mediated disease was sequentially studied in the rat following single i.v. injections of rabbit antibodies to basement membrane antigens prepared from kidney, lung and salivary gland tissues. Although each of the anti-bodies bound strongly to GBM, structural changes were initially subtle accompanied by proteinuria and hematuria. More severe structural changes related to dose and duration of the disease did not appear for several weeks.