Mode of activation of salt secretion by C-type natriuretic peptide in the shark rectal gland

1999 ◽  
Vol 277 (6) ◽  
pp. R1725-R1732 ◽  
Author(s):  
Patricio Silva ◽  
Richard J. Solomon ◽  
Franklin H. Epstein
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Squalus Acanthias ◽  
Rectal Gland ◽  
Stimulatory Action ◽  
Kinase C ◽  
Shark Rectal Gland ◽  
Pkc Activation ◽  
Stimulation Of

We studied the modes of activation of the salt-secreting rectal gland of the spiny dogfish, Squalus acanthias, by the native cardiac peptide CNP. The stimulatory action of CNP in isolated perfused glands is inhibited by 10 mM procaine, presumably by blocking release of vasoactive intestinal peptide (VIP) from nerves. Procaine reduces the slope of the dose-response curve of human CNP and that of shark CNP (each P < 0.0001). CNP increases short-circuit current in cultured rectal gland cells from 4.8 ± 1.6 to 27.0 ± 7.8 μA/cm2. It also stimulates the secretion of chloride in isolated perfused glands in the presence of 10 mM procaine from 72 ± 31 to 652 ± 173 μeq ⋅ h−1 ⋅ g−1. These results suggest that CNP has a direct cellular action not mediated by the neural release of VIP. The residual stimulation of perfused glands in the presence of procaine was almost completely inhibited by staurosporine [10 nM; an inhibitor of protein kinase C (PKC)] from 652 ± 173 to 237 ± 61 μeq ⋅ h−1 ⋅ g−1. Although CNP stimulates guanylyl cyclase in shark rectal gland, chloride secretion of perfused glands was not elicited by 8-bromoadenosine-cGMP (8-BrcGMP) alone nor by the activator of PKC phorbol ester. The combination of PKC activation and 8-BrcGMP infusion, however, stimulated chloride secretion in perfused glands from 94 ± 30 to 506 ± 61 μeq ⋅ h−1 ⋅ g−1, a level comparable to that observed in glands blocked with procaine. Several parallel pathways appear to be synergistic in activating chloride secretion stimulated by CNP in the rectal gland.

scholarly journals AMP-activated protein kinase and adenosine are both metabolic modulators that regulate chloride secretion in the shark rectal gland (Squalus acanthias)

2018 ◽  
Vol 314 (4) ◽  
pp. C473-C482
Author(s):  
Rugina I. Neuman ◽  
Juliette A. M. van Kalmthout ◽  
Daniel J. Pfau ◽  
Dhariyat M. Menendez ◽  
Lawrence H. Young ◽  
...  
Keyword(s):  
Feedback Inhibition ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Squalus Acanthias ◽  
Catalytic Subunit ◽  
Rectal Gland ◽  
Apical Side ◽  
Shark Rectal Gland ◽  
Amp Activated Protein Kinase

The production of endogenous adenosine during secretagogue stimulation of CFTR leads to feedback inhibition limiting further chloride secretion in the rectal gland of the dogfish shark (Squalus acanthias). In the present study, we examined the role of AMP-kinase (AMPK) as an energy sensor also modulating chloride secretion through CFTR. We found that glands perfused with forskolin and isobutylmethylxanthine (F + I), potent stimulators of chloride secretion in this ancient model, caused significant phosphorylation of the catalytic subunit Thr172 of AMPK. These findings indicate that AMPK is activated during energy-requiring stimulated chloride secretion. In molecular studies, we confirmed that the activating Thr172 site is indeed present in the α-catalytic subunit of AMPK in this ancient gland, which reveals striking homology to AMPKα subunits sequenced in other vertebrates. When perfused rectal glands stimulated with F + I were subjected to severe hypoxic stress or perfused with pharmacologic inhibitors of metabolism (FCCP or oligomycin), phosphorylation of AMPK Thr172 was further increased and chloride secretion was dramatically diminished. The pharmacologic activation of AMPK with AICAR-inhibited chloride secretion, as measured by short-circuit current, when applied to the apical side of shark rectal gland monolayers in primary culture. These results indicate that that activated AMPK, similar to adenosine, transmits an inhibitory signal from metabolism, that limits chloride secretion in the shark rectal gland.

Neuropeptide Y inhibits chloride secretion in the shark rectal gland

1993 ◽  
Vol 265 (2) ◽  
pp. R439-R446 ◽  
Author(s):  
P. Silva ◽  
F. H. Epstein ◽  
K. J. Karnaky ◽  
S. Reichlin ◽  
J. N. Forrest
Keyword(s):  
Neuropeptide Y ◽  
Direct Action ◽  
Short Circuit ◽  
Primary Cultures ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Rectal Gland ◽  
Maximal Effect ◽  
Gland Cells ◽  
Shark Rectal Gland

We studied the effects of the 36-amino acid peptide, neuropeptide Y (NPY), on salt secretion by the rectal gland of Squalus acanthias. We used three preparations: whole isolated perfused glands, freshly prepared separated rectal gland tubules, and confluent monolayers of cultured rectal gland cells. In perfused glands NPY inhibited secretion stimulated by vasoactive intestinal peptide (VIP), forskolin, or adenosine 3',5'-cyclic monophosphate (cAMP) and theophylline. Maximal inhibition of 63 +/- 3.4% was seen at 3 x 10(-8) M NPY, with half-maximal effect at 3 x 10(-9) M. NPY did not inhibit the basal activity of rectal gland adenylate cyclase or that stimulated by VIP. The inhibitory action of NPY was not prevented by procaine, nifedipine, or diltiazem, suggesting that it was not secondary to the release of somatostatin or other unknown neurotransmitters from rectal gland nerves. In confirmation, somatostatin was not detected in the venous effluent after administration of NPY. NPY also inhibited transport-related oxygen consumption in separated rectal gland tubules and inhibited short-circuit current generated by confluent monolayers of primary cultures of rectal gland cells. The results indicate that NPY inhibits chloride secretion by a direct action on cells of the shark rectal gland at a site distal to the generation of cAMP.

Atriopeptin stimulates chloride secretion in cultured shark rectal gland cells

1991 ◽  
Vol 260 (5) ◽  
pp. C1125-C1130 ◽  
Author(s):  
K. J. Karnaky ◽  
J. D. Valentich ◽  
M. G. Currie ◽  
W. F. Oehlenschlager ◽  
M. P. Kennedy
Keyword(s):  
Epithelial Cells ◽  
Plasma Membranes ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Rectal Gland ◽  
Cl Secretion ◽  
Intracellular Cgmp ◽  
Similar Dose ◽  
Shark Rectal Gland

Monolayer cultures of shark rectal gland (SRG) epithelial cells were treated with atriopeptin (AP), and the effects on Cl- secretion and intracellular guanosine 3',5'-cyclic monophosphate (cGMP) accumulation were examined. Basolateral or apical exposure to 10(-7) M AP markedly stimulated (8-fold) Cl(-)-dependent, bumetanide-sensitive, short-circuit current (Isc). The AP-stimulated Isc exhibited transient oscillations before reaching a steady state. This behavior is not observed when Isc is activated by other secretagogues such as vasoactive intestinal peptide, 2-chloroadenosine, forskolin, or ionomycin. Intracellular cGMP was concomitantly elevated (10-fold) by 10(-7) M AP. Both Isc stimulation and cGMP accumulation responses exhibited a similar dose dependency beginning at an AP concentration of 1 nM. The bilateral response to AP suggests the presence of receptors on both apical and basolateral plasma membranes. These results are the first demonstration of a direct effect of AP on Cl(-)-secreting epithelial cells. These data also suggest a role for cGMP in mediating Cl- secretion in these cells.

Changes in intracellular sodium with chloride secretion in dog tracheal epithelium

1986 ◽  
Vol 250 (4) ◽  
pp. C646-C650 ◽  
Author(s):  
S. R. Shorofsky ◽  
M. Field ◽  
H. A. Fozzard
Keyword(s):  
Steady State ◽  
Kinetic Models ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Tracheal Epithelium ◽  
Cl Secretion ◽  
Intracellular Na Activity ◽  
Sufficient Energy ◽  
Stimulation Of

Na-selective microelectrodes were employed to investigate the mechanism of Cl secretion by canine tracheal epithelium. In control tissues with a mean short-circuit current (Isc) of 30.1 microA/cm2, the intracellular Na activity (aiNa) was 10.7 mM. Following steady-state stimulation of Cl secretion with epinephrine (Isc = 126.4 microA/cm2), aiNa was 21.3 mM. These data indicate that there is sufficient energy in the Na gradient to drive Cl secretion by this tissue. When analyzed with simple kinetic models for the Na-K pump, they also suggest that the basolateral entry step involves the Na-K-2Cl cotransporter.

Adenosine 3',5'-cyclic monophosphate stimulates chloride secretion in A6 epithelia

1986 ◽  
Vol 251 (5) ◽  
pp. C810-C814 ◽  
Author(s):  
M. Yanase ◽  
J. S. Handler
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Apical Surface ◽  
Cyclic Monophosphate ◽  
A6 Epithelia ◽  
In Series ◽  
Cl Channels ◽  
Solution Bathing ◽  
Stimulation Of

Basal and aldosterone-stimulated short-circuit current (Isc) of A6 epithelia are known to be equivalent to net apical to basal Na flux and are completely inhibited by 0.05 mM amiloride added to the solution bathing the apical surface of the epithelium. In the absence of amiloride, the Isc stimulated by adenosine 3',5'-cyclic monophosphate (cAMP) is also equivalent to net apical to basal Na flux. However, amiloride does not completely inhibit the cAMP-stimulated Isc. In this study, the cAMP-stimulated, amiloride-insensitive Isc was characterized, using vasopressin or forskolin to raise cell cAMP. After basal Isc is inhibited by amiloride, forskolin stimulates Isc, conductance, and bidirectional 36Cl flux. Stimulation of Isc depends on the presence of both Na and Cl; stimulation of conductance depends on the presence of Cl. 36Cl flux studies showed that the cAMP-stimulated, amiloride-insensitive Isc is equivalent to net Cl flux. It is inhibited by ouabain and by furosemide or bumetanide added to the solution bathing the basal surface of the epithelium. In view of the effect of cAMP in some other epithelia, we suggest that cAMP activates apical membrane Cl channels that are in series with a Na-K-Cl cotransporter in the basolateral plasma membrane.

Mechanism of active chloride secretion by shark rectal gland: role of Na-K-ATPase in chloride transport

1977 ◽  
Vol 233 (4) ◽  
pp. F298-F306 ◽  
Author(s):  
P. Silva ◽  
J. Stoff ◽  
M. Field ◽  
L. Fine ◽  
J. N. Forrest ◽  
...  
Keyword(s):  
Chloride Transport ◽  
Sodium Concentration ◽  
Chloride Secretion ◽  
Squalus Acanthias ◽  
Rectal Gland ◽  
Tentative Hypothesis ◽  
Shark Rectal Gland ◽  
Electrochemical Equilibrium

The isolated rectal gland of Squalus acanthias was stimulated to secrete chloride against an electrical and a chemical gradient when perfused in vitro by theophylline and/or dibutyryl cyclic AMP. Chloride secretion was depressed by ouabain which inhibits Na-K-ATPase. Thiocyanate and furosemide also inhibited chloride secretion but ethoxzolamide, a carbonic anhydrase inhibitor, did not. Chloride transport was highly dependent on sodium concentration in the perfusate. The intracellular concentration of chloride averaged 70-80 meq/liter in intact glands, exceeding the level expected at electrochemical equilibrium and suggesting active transport of chloride into the cell. These features suggest a tentative hypothesis for chloride secretion by the rectal gland in which the uphill transport of chloride into the cytoplasm is coupled through a membrane carrier to the downhill movement of sodium along its electrochemical gradient. The latter is maintained by the Na-K-ATPase pump while chloride is extruded into the duct by electrical forces.

scholarly journals Aeromonas hydrophila Beta-Hemolysin Induces Active Chloride Secretion in Colon Epithelial Cells (HT-29/B6)

2004 ◽  
Vol 72 (8) ◽  
pp. 4848-4858 ◽  
Author(s):  
H. J. Epple ◽  
J. Mankertz ◽  
R. Ignatius ◽  
O. Liesenfeld ◽  
M. Fromm ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Aeromonas Hydrophila ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Human Colon ◽  
Chloride Secretion ◽  
Ion Secretion ◽  
Kinase C ◽  
Ht 29

ABSTRACT The diarrheal mechanisms in Aeromonas enteritis are not completely understood. In this study we investigated the effect of aeromonads and of their secretory products on ion secretion and barrier function of monolayers of human intestinal cells (HT-29/B6). Ion secretion was determined as a short-circuit current (ISC) of HT-29/B6 monolayers mounted in Ussing-type chambers. Transepithelial resistance (Rt) served as a measure of permeability. A diarrheal strain of Aeromonas hydrophila (strain Sb) added to the mucosal side of HT-29/B6 monolayers induced a significant ISC (39 ± 3 μA/cm2) and decreased the Rt to ∼10% of the initial value. A qualitatively identical response was obtained with sterile supernatant of strain Sb, and Aeromonas supernatant also induced a significant ISC in totally stripped human colon. Tracer flux and ion replacement studies revealed the ISC to be mainly accounted for by electrogenic Cl− secretion. Supernatant applied serosally completely abolished basal ISC. The supernatant-induced ISC was inhibited by the protein kinase C inhibitor chelerythrine, whereas a protein kinase A inhibitor (H8) and a Ca2+ chelator (BAPTA-AM) had no effect. Physicochemical properties indicated that the supernatant's active compound was an aerolysin-related Aeromonas beta-hemolysin. Accordingly, identical ISC and Rt responses were obtained with Escherichia coli lysates harboring the cloned beta-hemolysin gene from strain SB or the aerA gene encoding for aerolysin. Sequence comparison revealed a 64% homology between aerolysin and the beta-hemolysin cloned from Aeromonas sp. strain Sb. In conclusion, beta-hemolysin secreted by pathogenic aeromonads induces active Cl− secretion in the intestinal epithelium, possibly by channel insertion into the apical membrane and by activation of protein kinase C.

Protein kinase C does not participate in carbachol's secretory action in T84 cells

1992 ◽  
Vol 263 (1) ◽  
pp. C140-C146 ◽  
Author(s):  
R. P. Lindeman ◽  
H. S. Chase
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Current Response ◽  
T84 Cells ◽  
Cl Secretion ◽  
Kinase C ◽  
Secretory Action ◽  
Pkc Activation

We investigated the role of protein kinase C (PKC) in mediating carbachol's stimulation of transepithelial Cl- secretion in T84 cells. Direct PKC activation with phorbol 12-myristate 13-acetate (PMA) stimulated transepithelial Cl- transport (measured as the short-circuit current), demonstrating that PKC could interact with the secretory apparatus. Carbachol stimulated PKC activity, suggesting that the enzyme might participate in the hormone's action. Diacylglycerol metabolism inhibitors (DMIs), known to augment hormone-stimulated increases in diacylglycerol levels, potentiated the short-circuit current response to carbachol. The effect of DMIs was not due to amplification of carbachol-induced increases in PKC activity, however; PKC activity during carbachol stimulation was no higher in the presence of DMIs than in their absence. Augmentation of carbachol's action by DMIs appeared to be due to the direct activation of PKC which, like PMA, stimulated the Cl- conductance of the apical membrane (GCl). The effects of DMIs and carbachol on GCl were additive. Carbachol itself stimulated GCl but not by activating PKC; staurosporine did not blunt the effect of carbachol on GCl. Nor did staurosporine reduce the effect of carbachol on transepithelial Cl- secretion. These observations demonstrate that PKC does not participate in the secretory action of carbachol in T84 cells and suggest that direct PKC activation with DMIs and PMA stimulates an apical pool of PKC that is not accessible to carbachol applied to the basolateral membrane.

Regulation of chloride secretion in dog tracheal epithelium by protein kinase C

1987 ◽  
Vol 253 (6) ◽  
pp. C802-C808 ◽  
Author(s):  
R. A. Barthelson ◽  
D. B. Jacoby ◽  
J. H. Widdicombe
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Tracheal Epithelium ◽  
Base Line ◽  
Cl Secretion ◽  
Cell Extracts ◽  
Kinase C

The effects of stimulating protein kinase C on Cl- secretion across dog tracheal epithelium were investigated. The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), and the synthetic diacylglycerol, 1-oleolyl-2-acetylglycerol (OAG), which stimulate protein kinase C (PKC), both stimulated short-circuit current (Isc) with Kd of 10 nM and 1 microM, respectively. In Cl(-)-free solution, the increases in Isc were virtually abolished, suggesting that these compounds stimulate Cl- secretion, a hypothesis confirmed for TPA by measurement of 36Cl- fluxes. The stimulations of Cl- secretion were not sensitive to indomethacin, nor were cAMP levels elevated during stimulation. In addition to its transient stimulatory effect, TPA at high doses caused the eventual lowering of the base-line Isc and a block of subsequent stimulation by cAMP-mediated agonists. This was probably not the result of toxicity or an effect on adenylate cyclase or on cAMP-dependent protein kinase. Cell extracts from both cultured and native dog tracheal epithelial cells showed strong PKC activities. These results suggest that PKC may play a role in regulating Cl- secretion across dog tracheal epithelium.

Muscarinic receptor subtypes mediating the mucosal response to neural stimulation of guinea pig ileum

1987 ◽  
Vol 253 (3) ◽  
pp. G323-G329 ◽  
Author(s):  
H. V. Carey ◽  
X. Y. Tien ◽  
L. J. Wallace ◽  
H. J. Cooke
Keyword(s):  
Guinea Pig ◽  
Muscarinic Receptors ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Neural Stimulation ◽  
Secretory Response ◽  
Receptor Subtypes ◽  
Guinea Pig Ileum ◽  
Stimulation Of

Muscarinic receptors involved in the secretory response evoked by electrical stimulation of submucosal neurons were investigated in muscle-stripped flat sheets of guinea pig ileum set up in flux chambers. Neural stimulation produced a biphasic increase in short-circuit current due to active chloride secretion. Atropine and 4-diphenylacetoxy-N-methylpiperadine methiodide (4-DAMP) (10(-7) M) were more potent inhibitors of the cholinergic phase of the response than was pirenzepine. Dose-dependent increases in base-line short-circuit current were evoked by carbachol and bethanechol; 4-hydroxy-2-butynyl trimethylammonium chloride (McN A343) produced a much smaller effect. Tetrodotoxin abolished the effects of McN A343 but did not alter the responses of carbachol and bethanechol. McN A343 significantly reduced the cholinergic phase of the neurally evoked response and caused a rightward shift of the carbachol dose-response curve. All muscarinic compounds inhibited [3H]quinuclidinyl benzilate binding to membranes from mucosal scrapings, with a rank order of potency of 4-DAMP greater than pirenzepine greater than McN A343 greater than carbachol greater than bethanechol. These results suggest that acetylcholine released from submucosal neurons mediates chloride secretion by interacting with muscarinic cholinergic receptors that display a high binding affinity for 4-DAMP. Activation of neural muscarinic receptors makes a relatively small contribution to the overall secretory response.

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