A novel role for carbon monoxide as a potent regulator of intracellular Ca2+and nitric oxide in rat pancreatic acinar cells

2014 ◽  
Vol 307 (11) ◽  
pp. C1039-C1049 ◽  
Author(s):  
Amira Moustafa ◽  
Yoshiaki Habara

Carbon monoxide (CO) is known as an essential gaseous messenger that regulates a wide array of physiological and pathological processes, similar to nitric oxide (NO) and hydrogen sulfide. The aim of the present study was to elucidate the potential role of CO in Ca2+homeostasis and to explore the underlying mechanisms in pancreatic acinar cells. The exogenous application of a CO-releasing molecule dose-dependently increased intracellular Ca2+concentration ([Ca2+]i). A heme oxygenase (HO) inducer increased [Ca2+]iin a concentration-dependent manner, and the increase was diminished by an HO inhibitor. The CO-induced [Ca2+]iincrease persisted in the absence of extracellular Ca2+, indicating that Ca2+release is the initial source for the increase. The inhibition of G protein, phospholipase C (PLC), and inositol 1,4,5-trisphosphate (IP3) receptor diminished the CO-induced [Ca2+]iincrease. CO upregulated endothelial nitric oxide synthase (eNOS) expression and stimulated NO production, and NOS inhibitor, calmodulin inhibitor, or the absence of extracellular Ca2+eliminated the latter response. Blocking the phosphatidylinositol 3-kinase (PI3K)-Akt/protein kinase B (PKB) pathway abolished CO-induced NO production. Pretreatment with an NOS inhibitor, NO scavenger, or soluble guanylate cyclase inhibitor, did not affect the CO-induced [Ca2+]iincrease, indicating that NO, soluble guanylate cyclase, and cyclic guanosine 5′-monophosphate are not involved in the CO-induced [Ca2+]iincrease. CO inhibited the secretory responses to CCK-octapeptide or carbachol. We conclude that CO acts as a regulator not only for [Ca2+]ihomeostasis via a PLC-IP3-IP3receptor cascade but also for NO production via the calmodulin and PI3K-Akt/PKB pathway, and both CO and NO interact. Moreover, CO may provide potential therapy to ameliorate acute pancreatitis by inhibiting amylase secretion.

1994 ◽  
Vol 266 (3) ◽  
pp. G350-G356 ◽  
Author(s):  
A. Gukovskaya ◽  
S. Pandol

Guanosine 3',5'-cyclic monophosphate (cGMP) rise is one of the early events in neurotransmitter or hormone-induced cascade of reactions in pancreatic acinar cells. The mechanism of agonist-stimulated guanylyl cyclase activation in these cells remains, however, unknown. In the present work, mechanisms of cGMP rise, as well as of Ca2+ influx, induced by carbachol were studied on acinar cells isolated from rat and guinea pig pancreas. In both types of acinar cells, blocking nitric oxide (NO) production by inhibitors of NO synthase, NG-monomethyl-L-arginine (L-NMMA) or NG-nitro-L-arginine, abolished carbachol-induced cGMP rise in a dose-dependent manner. The inhibition was reversed by addition of excess L-arginine. L-NMMA also caused inhibition of the basal cGMP level, suggesting a role for NO in cGMP homeostasis in resting cells. Carbachol was found to increase [3H]arginine conversion to [3H]citrulline. This conversion was inhibited by L-NMMA. By contrast, inhibition of carbon monoxide production by Zn-protoporphyrin did not affect carbachol-stimulated cellular cGMP levels. There was no increase in cellular cGMP levels in response to exogenous arachidonic acid (AA). Blocking of lipoxygenase oxidation of AA by nordihydroguaiaretic acid did not produce any changes in carbachol-induced cGMP rise. Indomethacin, a cyclooxygenase inhibitor, increased basal cGMP level through L-NMMA-sensitive mechanism. Blockade of NO production inhibited carbachol-induced increase in 45Ca2+ uptake in both guinea pig and rat acinar cells. The concentration-response curves for inhibition by L-NMMA of 45Ca2+ uptake and cGMP formation were superimposable. L-NMMA also suppressed stimulation of Mn2+ quenching by carbachol in fura 2-loaded acini.(ABSTRACT TRUNCATED AT 250 WORDS)


1994 ◽  
Vol 267 (2) ◽  
pp. C385-C393 ◽  
Author(s):  
H. Zhao ◽  
X. Xu ◽  
K. Ujiie ◽  
R. A. Star ◽  
S. Muallem

Recently, we showed that NO2- increases gap junction (GJ) permeability and synchronizes intracellular Ca2+ concentration oscillations in pancreatic acini (Loessburg et al., J. Biol. Chem. 268: 19769-19775, 1993). NO2- is also an end product of nitric oxide (NO) production and metabolism. Because of the effect of NO2- on GJ permeability and the possible importance of NO2- in NO metabolism and cytotoxicity, we used pancreatic acinar cells and intracellular pH (pHi) measurements to study the interaction of nitrogen oxides and NO2- with cellular proteins. Exposing cells to NO2- resulted in a concentration-dependent cytosolic acidification. The acidification did not require the transport of NO2- and was not mediated by diffusion of HNO2. Because the acidification was prevented by CO2-HCO3- and inhibition of carbonic anhydrase, it is possible that other nitrogen oxides present in a solution containing NO2- enter the cells by diffusion and interact with OH- or H2O to stably acidify the cytosol. NO2- itself is shown to be transported by the HCO3- transporters present in the plasma membrane. Thus manipulation of the cellular Cl- gradient and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) were used to show Cl-/NO2- exchange, whereas stimulation of external Na(+)-dependent amiloride-insensitive and DIDS-sensitive pHi increase in acidified cells was used to demonstrate a Na(+)-(NO2-)n cotransport. Hence NO2- can be a convenient substitute for HCO3- when studying HCO3- transport in an open system. The studies also show that cellular levels of nitrogen oxides and NO2- can be modulated by the cellular HCO3(-)-buffering system.(ABSTRACT TRUNCATED AT 250 WORDS)


1992 ◽  
Vol 263 (6) ◽  
pp. F1020-F1025 ◽  
Author(s):  
R. M. Edwards ◽  
M. Pullen ◽  
P. Nambi

The effects of endothelins (ET) on guanosine 3',5'-cyclic monophosphate (cGMP) levels in intact rat glomeruli were examined. ET-3 produced a rapid approximately fivefold increase in cGMP levels with the maximum effect occurring at 1 min. The ET-3-induced increase in cGMP accumulation occurred in the absence and presence of 3-isobutyl-1-methylxanthine. ET-1, ET-2, ET-3, and the structurally related toxin, sarafotoxin S6c, all increased glomerular cGMP levels in a concentration-dependent manner and with similar potencies (EC50 approximately 15-30 nM). The L-arginine analogue, N omega-nitro-L-arginine (L-NNA), reduced basal levels of cGMP and also totally inhibited ET-induced increases in cGMP as did methylene blue, an inhibitor of soluble guanylate cyclase. The effect of L-NNA was attenuated by L-arginine but not by D-arginine. The stimulation of cGMP accumulation by ET-3 was dependent on extracellular Ca2+ and was additive to atriopeptin III but not to acetylcholine. The ETA-selective antagonist, BQ 123, had no effect on ET-3-induced formation of cGMP. Glomerular membranes displayed high-affinity (Kd = 130-150 pM) and high-density (approximately 2.0 pmol/mg) binding sites for 125I-ET-1 and 125I-ET-3. ET-1, ET-3, and sarafotoxin S6c displaced 125I-ET-1 binding to glomerular membranes with similar affinities. BQ 123 had no effect on 125I-ET-1 binding. We conclude that ET increases cGMP levels in glomeruli by stimulating the formation of a nitric oxide-like factor that activates soluble guanylate cyclase. This effect of ET appears to be mediated by activation of ETB receptors and may serve to modulate the contractile effects of ET.


2004 ◽  
Vol 89 (5) ◽  
pp. 1157-1165 ◽  
Author(s):  
Mariluz Hernandez-Viadel ◽  
Anna F. Castoldi ◽  
Teresa Coccini ◽  
Luigi Manzo ◽  
Slaven Erceg ◽  
...  

2018 ◽  
Vol 21 ◽  
pp. 38-45 ◽  
Author(s):  
Ariane Migliato Martinelli ◽  
Carla Nascimento dos Santos Rodrigues ◽  
Thiago Francisco de Moraes ◽  
Gerson Jhonatan Rodrigues

Purpose. In endothelial cells, investigate if the soluble guanylate cyclase (sGC) activation or stimulation is able to potentiate the relaxation in vessels. Methods. Aortic and coronary rings with and without endothelium were placed in a myograph and cumulative concentration-effect curves for DETA-NO or ataciguat were performed. Nitric oxide (NO) were measured by fluorescence or by selective electrode in human umbilical endothelial cells (HUVECs) in response to some treatments, including ataciguat, 8-Br-cGMP and A23187. Results. The presence of the endothelium potentiated the relaxation induced by DETA-NO in aortic and coronary rings. In addition, in aortic rings the endothelium potentiated the relaxation induced by ataciguat. In the presence of nitric oxide synthase (NOS) inhibitor, the endothelium effect was abolished to DETA-NO or ataciguat, in both vessels. Ataciguat, 8-Br-cGMP and A23187 were able to induce NO production in HUVECs cells. In the presence of NOS inhibitor, the NO production induced by ataciguat and 8-Br-cGMP was abolished. Conclusions. Our results suggest that in aortic and coronary rings the endothelium potentiates the relaxation induced by activation or stimulation of sGC through a mechanism dependent of NOS activation. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.


1997 ◽  
Vol 273 (2) ◽  
pp. R823-R827 ◽  
Author(s):  
S. A. Davies ◽  
E. J. Stewart ◽  
G. R. Huesmann ◽  
N. J. Skaer ◽  
S. H. Maddrell ◽  
...  

Activation of the nitric oxide (NO) and guanosine 3', 5'-cyclic monophosphate (cGMP) signaling pathway stimulates fluid secretion by the Drosophila melanogaster Malpighian tubule. The neuropeptide cardioacceleratory peptide 2b (CAP2b) has been previously shown to stimulate fluid secretion in this epithelium by elevating intracellular cGMP levels. Therefore, it was of interest to investigate if CAP2b acts through NO in isolated tubules and thus presumably through stimulation of a tubule NO synthase (NOS). We show here by reverse-transcription polymerase chain reaction that Drosophila NOS (dNOS) is expressed in Malpighian tubules. Biochemical assays of NOS activity in whole tubules show that CAP2b significantly stimulates NOS activity. Additionally, fluid secretion and cyclic nucleotide assays show that CAP2b-induced elevation of intracellular cGMP levels and fluid secretion rates are dependent on the activation of a soluble guanylate cyclase. Treatment of tubules with a specific NOS inhibitor abolishes the CAP2b-induced rise in intracellular cGMP levels. These data indicate that CAP2b stimulates NOS and therefore, endogenous NO production, which, in turn, stimulates a soluble guanylate cyclase. This is the first demonstration of stimulation of an endogenous NOS by a defined peptide in Drosophila.


2006 ◽  
Vol 291 (6) ◽  
pp. H2772-H2778 ◽  
Author(s):  
Fady T. Botros ◽  
L. Gabriel Navar

Heme oxygenases (HO-1 and HO-2) catalyze the conversion of heme to carbon monoxide (CO), iron, and biliverdin. CO causes vasorelaxation via stimulation of soluble guanylate cyclase (sGC) and/or activation of calcium-activated potassium channels. Because nitric oxide (NO) exerts effects via the same pathways, we tested the interaction between CO and NO on rat afferent arterioles (AAs) using the blood-perfused juxtamedullary nephron preparation. AAs were superfused with either tricarbonyldichlororuthenium (II) dimer, known as CO releasing molecule (CORM-2), 10 μmol/l CO solution, or 15 μmol/l chromium mesoporphyrin (CrMP, HO inhibitor). AAs were also superfused with 1 mmol/l Nω-nitro-l-arginine (l-NNA) to inhibit NO synthase (NOS) or 10 μmol/l 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one to inhibit sGC, and then CrMP was superfused during NOS inhibition or sGC inhibition. Treatment with 150 and 300 μmol/l CORM-2 or with CO (10 μmol/l) significantly dilated AAs (22.0 ± 0.9 and 22.8 ± 0.9 vs. 18.3 ± 0.9 μm, n = 5, P < 0.05; and 26.0 ± 1.4 vs. 18.8 ± 0.7 μm, n = 5, P < 0.05). In untreated vessels, HO inhibition did not alter AA diameter (17.5 ± 0.7 vs. 17.2 ± 0.6 μm, n = 7, P > 0.05); however, during inhibition of NO production, which constricted arterioles to 14.6 ± 1.2 μm, n = 6, P < 0.05, concurrent HO inhibition led to further vasoconstriction (11.7 ± 1.6 μm, n = 6, P < 0.05). CORM-2 attenuated the l-NNA-induced vasoconstriction. Inhibition of sGC caused significant constriction (15.7 ± 0.4 vs. 18.8 ± 0.4 μm, n = 6, P < 0.05). HO inhibition during sGC inhibition did not cause further change in AAs (15.5 ± 0.7 μm, n = 6). We conclude that endogenously produced CO does not exert a perceptible influence on AA diameter in the presence of intact NO system; however, when NO production is inhibited, CO serves as an important renoprotective reserve mechanism to prevent excess afferent arteriolar constriction.


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