Decrease in rat submandibular acinar cell volume during ACh stimulation

1990 ◽  
Vol 258 (6) ◽  
pp. G878-G886 ◽  
Author(s):  
T. Nakahari ◽  
M. Murakami ◽  
H. Yoshida ◽  
M. Miyamoto ◽  
Y. Sohma ◽  
...  
Keyword(s):  
Cell Volume ◽  
Acinar Cell ◽  
Basolateral Membrane ◽  
Fluid Secretion ◽  
Salivary Secretion ◽  
Impedance Method ◽  
Fluid Flux ◽  
Secretory Rate ◽  
Morphometric Method ◽  
Volume Decrease

Changes in acinar cell volume were measured in the perfused submandibular gland of the rat at 23 degrees C during salivary secretion induced by acetylcholine (ACh). Cellular volume was monitored by two methods: the impedance method and the morphometric method using video-enhanced contrast optical microscopy. Both measurements revealed a decrease in acinar cell volume in response to 1 microM ACh. Within the 1st min of stimulation, secretion increased to the initial maximum (initial secretion), and cell shrinkage occurred. During sustained stimulation, secretory rate and cell volume were maintained at the plateau level (steady secretion). The decrease in cell volume was 71.8 +/- 2.9% of resting volume (means +/- SE, n = 8) as measured by the impedance method and 76.1 +/- 2.0% (n = 20) as measured by the morphometric method. With the removal of ACh, cell volume increased to 111.6 +/- 2.7% (n = 8) of the prestimulation level as measured by the impedance method and 108.8 +/- 1.5% (n = 20) as measured by the morphometric method, and then recovered to the prestimulation level slowly. The weight of the gland decreased significantly during stimulation. These findings proved that volume decrease occurred during stimulation. The measurement of cell volume gave the net fluid flux of the acinar cell compartment. The net fluid flux and the rate of salivary secretion gave an estimation of the fluid influx across the basolateral membrane. These findings suggest that a transcellular route for fluid secretion exists in the salivary gland.

scholarly journals Adenovirus-mediated hAQP1 expression in irradiated mouse salivary glands causes recovery of saliva secretion by enhancing acinar cell volume decrease

Gene Therapy ◽  
2016 ◽  
Vol 23 (7) ◽  
pp. 572-579 ◽  
Author(s):  
L Y Teos ◽  
C-Y Zheng ◽  
X Liu ◽  
W D Swaim ◽  
C M Goldsmith ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Cell Volume ◽  
Acinar Cell ◽  
Saliva Secretion ◽  
Volume Decrease

Apparent Synthesis of Submaxillary Gland Amylase During Pilocarpine Administration

1956 ◽  
Vol 187 (2) ◽  
pp. 403-406 ◽  
Author(s):  
Leon H. Schneyer ◽  
Charlotte A. Schneyer
Keyword(s):  
Subcutaneous Administration ◽  
Submaxillary Gland ◽  
Fluid Secretion ◽  
Salivary Secretion ◽  
Secretory Proteins ◽  
Parotid Glands ◽  
Short Term ◽  
Secretory Rate ◽  
Appreciable Increase ◽  
Expected Increase

Administration of the parasympathomimetic drug pilocarpine has generally been observed to result in an increased rate of salivary secretion accompanied by depletion of gland stores of specific secretory proteins. In the experiments reported here, the expected increase in secretory rate and depletion of amylase stores were observed for the parotid glands of the rat after subcutaneous administration of pilocarpine. In the case of the sub-maxillary glands, short-term stimulation by pilocarpine, although observed to result in the expected increase in the rate of fluid secretion, led to no detectable depletion but to a rapid and appreciable increase in gland levels of amylase activity. Although the mechanism of this effect remains to be established, it appears possible that in this system stimulation by the parasympathomimetic agent pilocarpine results in an unmasking of a direct effect of stimulation on the process of synthesis of new enzyme.

Secretion of saliva by the rabbit mandibular gland in vitro : the role of anions

1981 ◽  
Vol 296 (1080) ◽  
pp. 179-192 ◽  
Keyword(s):  
Mandibular Gland ◽  
Fluid Secretion ◽  
Salivary Secretion ◽  
Suitable Alternative ◽  
Secretory Rate ◽  
Complete Replacement ◽  
Primary Fluid ◽  
Gland Duct

Salivary glands form their secretions by first elaborating an isotonic plasma-like primary fluid in the endpieces and then modifying the composition of this secretion during its passage along the gland duct system. We have studied the role of extracellular anions in both primary secretion and ductal modification with a recently developed technique for isolation and perfusion of the rabbit mandibular gland. Neither of the major extracellular anions (Cl - or HCO - 3 ) is essential for primary fluid secretion. HCO - 3 can be removed altogether and replaced with Cl - without diminution in secretory rate, provided that extracellular pH is maintained at 7.4, and its replacement with acetate actually enhances secretion. Complete replacement of Cl - with Br - also enhances secretion and replacement with I - , NO - 3 , CH 3 SO 4 or isethionate supports secretion but at progressively diminishing rates. Our data do not yet allow us to distinguish between an electroneutral Na + -Cl - cotransport model or a double countertransport (Na + -H + plus Cl - -HCO - 3 ) model as the basis of primary salivary secretion, or to propose any more suitable alternative model. With respect to ductal modification of the primary saliva, HCO - 3 omission inhibits ductal Na + absorption (i.e. salivary Na + concentration rises). This inhibition is probably related to an effect of pH on the postulated Na + -H + exchange mechanism in the luminal duct membrane since it can also be induced by lowering perfusate pH, and reversed by substitution of perfusate HCO - 3 with acetate (which enters saliva) but not HEPES (which does not enter the saliva). Substitution of perfusate Cl - with other anions seems not to inhibit ductal Na+ and K + transport markedly.

Dibutyryl cAMP activates bumetanide-sensitive electrolyte transport in Malpighian tubules

1991 ◽  
Vol 261 (3) ◽  
pp. C521-C529 ◽  
Author(s):  
J. L. Hegarty ◽  
B. Zhang ◽  
T. L. Pannabecker ◽  
D. H. Petzel ◽  
M. D. Baustian ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Fluid Secretion ◽  
Ringer Solution ◽  
Malpighian Tubules ◽  
Membrane Voltage ◽  
Dibutyryl Camp ◽  
K Secretion ◽  
Transepithelial Voltage

The effects of dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) and bumetanide (both 10(-4) M) on transepithelial Na+, K+, Cl-, and fluid secretion and on tubule electrophysiology were studied in isolated Malpighian tubules of the yellow fever mosquito Aedes aegypti. Peritubular DBcAMP significantly increased Na+, Cl-, and fluid secretion but decreased K+ secretion. In DBcAMP-stimulated tubules, bumetanide caused Na+, Cl-, and fluid secretion to return to pre-cAMP control rates and K+ secretion to decrease further. Peritubular bumetanide significantly increased Na+ secretion and decreased K+ secretion so that Cl- and fluid secretion did not change. In bumetanide-treated tubules, the secretagogue effects of DBcAMP are blocked. In isolated Malpighian tubules perfused with symmetrical Ringer solution, DBcAMP significantly hyperpolarized the transepithelial voltage (VT) and depolarized the basolateral membrane voltage (Vbl) with no effect on apical membrane voltage (Va). Total transepithelial resistance (RT) and the fractional resistance of the basolateral membrane (fRbl) significantly decreased. Bumetanide also hyperpolarized VT and depolarized Vbl, however without significantly affecting RT and fRbl. Together these results suggest that, in addition to stimulating electroconductive transport, DBcAMP also activates a nonconductive bumetanide-sensitive transport system in Aedes Malpighian tubules.

Dependence of ion fluxes on fluid transport by rat proximal tubule

1986 ◽  
Vol 250 (4) ◽  
pp. F680-F689 ◽  
Author(s):  
K. Bomsztyk ◽  
F. S. Wright
Keyword(s):  
Proximal Tubule ◽  
Fluid Transport ◽  
Rat Kidney ◽  
Water Flux ◽  
Fluid Secretion ◽  
Proximal Convoluted Tubule ◽  
Ion Fluxes ◽  
Fluid Absorption ◽  
Fluid Flux ◽  
K Transport

The effects of changes in transepithelial water flux (Jv) on sodium, chloride, calcium, and potassium transport by the proximal convoluted tubule were examined by applying a microperfusion technique to surface segments in kidneys of anesthetized rats. Perfusion solutions were prepared with ion concentrations similar to those in fluid normally present in the later parts of the proximal tubule. Osmolality of the perfusate was adjusted with mannitol. With no mannitol in the perfusates, net fluid absorption was observed. Addition of increasing amounts of mannitol first reduced Jv to zero and then reversed net fluid flux. At the maximal rates of fluid absorption, net absorption of Na, Cl, Ca, and K was observed. When Jv was reduced to zero, Na, Cl, and Ca absorption were reduced and K entered the lumen. Na, Cl, and Ca secretion occurred in association with the highest rates of net fluid secretion. The lumen-positive transepithelial potential progressively increased as the net fluid flux was reduced to zero and then reversed. The results demonstrate that changes in net water flux can affect Na, Cl, Ca, and K transport by the proximal convoluted tubule of the rat kidney. These changes in net ion fluxes are not entirely accounted for by changes in bulk-phase transepithelial electrochemical gradients.

Hyperosmotic and isosmotic shrinkage differentially affect protein phosphorylation and ion transport

2012 ◽  
Vol 90 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Svetlana V. Koltsova ◽  
Olga A. Akimova ◽  
Sergei V. Kotelevtsev ◽  
Ryszard Grygorczyk ◽  
Sergei N. Orlov
Keyword(s):  
Ion Transport ◽  
Protein Phosphorylation ◽  
Cell Volume ◽  
Mdck Cells ◽  
Rat Aorta ◽  
Cellular Functions ◽  
Hypertonic Medium ◽  
Mitogen Activated Protein ◽  
Volume Decrease ◽  
In Cells

In the present work, we compared the outcome of hyperosmotic and isosmotic shrinkage on ion transport and protein phosphorylation in C11-MDCK cells resembling intercalated cells from collecting ducts and in vascular smooth muscle cells (VSMC) from the rat aorta. Hyperosmotic shrinkage was triggered by cell exposure to hypertonic medium, whereas isosmotic shrinkage was evoked by cell transfer from an hypoosmotic to an isosmotic environment. Despite a similar cell volume decrease of 40%–50%, the consequences of hyperosmotic and isosmotic shrinkage on cellular functions were sharply different. In C11-MDCK and VSMC, hyperosmotic shrinkage completely inhibited Na+,K+-ATPase and Na+,Pi cotransport. In contrast, in both types of cells isosmotic shrinkage slightly increased rather than suppressed Na+,K+-ATPase and did not change Na+,Pi cotransport. In C11-MDCK cells, phosphorylation of JNK1/2 and Erk1/2 mitogen-activated protein kinases was augmented in hyperosmotically shrunken cells by ∼7- and 2-fold, respectively, but was not affected in cells subjected to isosmotic shrinkage. These results demonstrate that the data obtained in cells subjected to hyperosmotic shrinkage cannot be considered as sufficient proof implicating cell volume perturbations in the regulation of cellular functions under isosmotic conditions.

scholarly journals Human trabecular meshwork cell volume regulation

2002 ◽  
Vol 283 (1) ◽  
pp. C315-C326 ◽  
Author(s):  
Claire H. Mitchell ◽  
Johannes C. Fleischhauer ◽  
W. Daniel Stamer ◽  
K. Peterson-Yantorno ◽  
Mortimer M. Civan
Keyword(s):  
Cell Volume ◽  
Trabecular Meshwork ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Channel Blockers ◽  
Uptake Mechanism ◽  
Fluid Uptake ◽  
Intracellular Ca ◽  
Predominant Effect ◽  
Volume Decrease

The volume of certain subpopulations of trabecular meshwork (TM) cells may modify outflow resistance of aqueous humor, thereby altering intraocular pressure. This study examines the contribution that Na+/H+, Cl−/HCO[Formula: see text]exchange, and K+-Cl− efflux mechanisms have on the volume of TM cells. Volume, Cl− currents, and intracellular Ca2+ activity of cultured human TM cells were studied with calcein fluorescence, whole cell patch clamping, and fura 2 fluorescence, respectively. At physiological bicarbonate concentration, the selective Na+/H+ antiport inhibitor dimethylamiloride reduced isotonic cell volume. Hypotonicity triggered a regulatory volume decrease (RVD), which could be inhibited by the Cl− channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), the K+channel blockers Ba2+ and tetraethylammonium, and the K+-Cl− symport blocker [(dihydroindenyl)oxy]alkanoic acid. The fluid uptake mechanism in isotonic conditions was dependent on bicarbonate; at physiological levels, the Na+/H+ exchange inhibitor dimethylamiloride reduced cell volume, whereas at low levels the Na+-K+-2Cl− symport inhibitor bumetanide had the predominant effect. Patch-clamp measurements showed that hypotonicity activated an outwardly rectifying, NPPB-sensitive Cl− channel displaying the permeability ranking Cl− > methylsulfonate > aspartate. 2,3-Butanedione 2-monoxime antagonized actomyosin activity and both increased baseline [Ca2+] and abolished swelling-activated increase in [Ca2+], but it did not affect RVD. Results indicate that human TM cells display a Ca2+-independent RVD and that volume is regulated by swelling-activated K+ and Cl− channels, Na+/H+ antiports, and possibly K+-Cl− symports in addition to Na+-K+-2Cl− symports.

scholarly journals Release of taurine and glutamate contributes to cell volume regulation in human retinal Müller cells: differences in modulation by calcium

2018 ◽  
Vol 120 (3) ◽  
pp. 973-984 ◽  
Author(s):  
Vanina Netti ◽  
Alejandro Pizzoni ◽  
Martha Pérez-Domínguez ◽  
Paula Ford ◽  
Herminia Pasantes-Morales ◽  
...  
Keyword(s):  
Cell Volume ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Müller Cells ◽  
Anion Channel ◽  
Müller Cell ◽  
Regulatory Mechanisms ◽  
Muller Cells ◽  
Muller Cell ◽  
Volume Decrease

Neuronal activity in the retina generates osmotic gradients that lead to Müller cell swelling, followed by a regulatory volume decrease (RVD) response, partially due to the isoosmotic efflux of KCl and water. However, our previous studies in a human Müller cell line (MIO-M1) demonstrated that an important fraction of RVD may also involve the efflux of organic solutes. We also showed that RVD depends on the swelling-induced Ca2+ release from intracellular stores. Here we investigate the contribution of taurine (Tau) and glutamate (Glu), the most relevant amino acids in Müller cells, to RVD through the volume-regulated anion channel (VRAC), as well as their Ca2+ dependency in MIO-M1 cells. Swelling-induced [3H]Tau/[3H]Glu release was assessed by radiotracer assays and cell volume by fluorescence videomicroscopy. Results showed that cells exhibited an osmosensitive efflux of [3H]Tau and [3H]Glu (Tau > Glu) blunted by VRAC inhibitors 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)-oxybutyric acid and carbenoxolone reducing RVD. Only [3H]Tau efflux was mainly dependent on Ca2+ release from intracellular stores. RVD was unaffected in a Ca2+-free medium, probably due to Ca2+-independent Tau and Glu release, but was reduced by chelating intracellular Ca2+. The inhibition of phosphatidylinositol-3-kinase reduced [3H]Glu efflux but also the Ca2+-insensitive [3H]Tau fraction and decreased RVD, providing evidence of the relevance of this Ca2+-independent pathway. We propose that VRAC-mediated Tau and Glu release has a relevant role in RVD in Müller cells. The observed disparities in Ca2+ influence on amino acid release suggest the presence of VRAC isoforms that may differ in substrate selectivity and regulatory mechanisms, with important implications for retinal physiology. NEW & NOTEWORTHY The mechanisms for cell volume regulation in retinal Müller cells are still unknown. We show that swelling-induced taurine and glutamate release mediated by the volume-regulated anion channel (VRAC) largely contributes the to the regulatory volume decrease response in a human Müller cell line. Interestingly, the hypotonic-induced efflux of these amino acids exhibits disparities in Ca2+-dependent and -independent regulatory mechanisms, which strongly suggests that Müller cells may express different VRAC heteromers formed by the recently discovered leucine-rich repeat containing 8 (LRRC8) proteins.

scholarly journals Electrogenic NBCe1 (SLC4A4), but not electroneutral NBCn1 (SLC4A7), cotransporter undergoes cholinergic-stimulated endocytosis in salivary ParC5 cells

2008 ◽  
Vol 295 (5) ◽  
pp. C1385-C1398 ◽  
Author(s):  
Clint Perry ◽  
David O. Quissell ◽  
Mary E. Reyland ◽  
Irina I. Grichtchenko
Keyword(s):  
Membrane Trafficking ◽  
Basolateral Membrane ◽  
Fluorescent Microscopy ◽  
Acinar Cells ◽  
Fluid Secretion ◽  
Parotid Glands ◽  
Calmodulin Antagonist ◽  
Parotid Acinar Cells ◽  
Early Endosomes ◽  
Gf 109203X

Cholinergic agonists are major stimuli for fluid secretion in parotid acinar cells. Saliva bicarbonate is essential for maintaining oral health. Electrogenic and electroneutral Na+-HCO3− cotransporters (NBCe1 and NBCn1) are abundant in parotid glands. We previously reported that angiotensin regulates NBCe1 by endocytosis in Xenopus oocytes. Here, we studied cholinergic regulation of NBCe1 and NBCn1 membrane trafficking by confocal fluorescent microscopy and surface biotinylation in parotid epithelial cells. NBCe1 and NBCn1 colocalized with E-cadherin monoclonal antibody at the basolateral membrane (BLM) in polarized ParC5 cells. Inhibition of constitutive recycling with the carboxylic ionophore monensin or the calmodulin antagonist W-13 caused NBCe1 to accumulate in early endosomes with a parallel loss from the BLM, suggesting that NBCe1 is constitutively endocytosed. Carbachol and PMA likewise caused redistribution of NBCe1 from BLM to early endosomes. The PKC inhibitor, GF-109203X, blocked this redistribution, indicating a role for PKC. In contrast, BLM NBCn1 was not downregulated in parotid acinar cells treated with constitutive recycling inhibitors, cholinergic stimulators, or PMA. We likewise demonstrate striking differences in regulation of membrane trafficking of NBCe1 vs. NBCn1 in resting and stimulated cells. We speculate that endocytosis of NBCe1, which coincides with the transition to a steady-state phase of stimulated fluid secretion, could be a part of acinar cell adjustment to a continuous secretory response. Stable association of NBCn1 at the membrane may facilitate constitutive uptake of HCO3− across the BLM, thus supporting HCO3− luminal secretion and/or maintaining acid-base homeostasis in stimulated cells.

Regulation of electrolyte and fluid secretion in salivary acinar cells

1992 ◽  
Vol 263 (6) ◽  
pp. G823-G837 ◽  
Author(s):  
B. Nauntofte
Keyword(s):  
Ionic Composition ◽  
Basolateral Membrane ◽  
Acinar Cells ◽  
Fluid Secretion ◽  
Receptor Activation ◽  
Exchange Mechanism ◽  
Luminal Membrane ◽  
Net Uptake ◽  
Cl Channels ◽  
Simultaneous Activation

The primary secretion from exocrine gland cells is a fluid rich in Na+ and Cl- with a plasmalike ionic composition. Activation of specific receptors on the plasma membrane by hormones and neurotransmitters, which leads to activation of the phosphoinositol metabolism, results in release of Ca2+ from internal Ca2+ stores. Intracellular free Ca2+ concentration ([Ca2+]i) then rises simultaneously at both the basolateral and luminal parts of the acinar cell, reaching maximum values within 1 s after stimulation. In parotid acinar cells, increased [Ca2+]i activates the opening of maxi K+ channels located on the basolateral membrane and Cl- channels presumably located on the luminal membrane, resulting in rapid loss of K+ and Cl- and water and cell shrinkage. Extracellular electroneutrality is maintained by a paracellular Na+ flux into the lumen. Because of the simultaneous activation of K+ and Cl- channels, secretion occurs at a virtually constant membrane potential of about -60 mV. After maximal muscarinic cholinergic stimulation, loss of K+, Cl-, and water results in an approximate 25% reduction in cell volume within 10-15 s after receptor activation. Concomitant with loss of Cl-, there is a loss of HCO3- from the cell, causing a decrease in intracellular pH of 0.1 pH units because of the carbonic anhydrase-mediated conversion of CO2 into H+ and HCO3-. H+ generated from the metabolism and HCO3- production is compensated for by extrusion of H+ by a Na(+)-H+ exchange mechanism, which is responsible for approximately 75% of net Na+ gain that occurs after stimulation. Increased [Na+]i activates the Na(+)-K+ pump, which in turn extrudes Na+ from the cells. In both the unstimulated and stimulated states, cellular production of HCO3- can drive a net uptake of Cl- via the Cl(-)-HCO3- exchange mechanism operating in parallel with the Na(+)-H+ exchanger. The operation of the Cl(-)-HCO3- exchanger is, together with a Na(+)-K(+)-2Cl- cotransport system, essential for maintainance of a high [Cl-]i both in the unstimulated state and during Cl- reuptake.

Sign in / Sign up

Export Citation Format

Share Document