Effect of locally applied drugs on the pH of luminal fluid in the endolymphatic sac of guinea pig

2000 ◽  
Vol 279 (5) ◽  
pp. R1695-R1700 ◽  
Author(s):  
Vincent Couloigner ◽  
Marie Teixeira ◽  
Philippe Hulin ◽  
Olivier Sterkers ◽  
Maurice Bichara ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Guinea Pig ◽  
Atpase Activity ◽  
Acid Secretion ◽  
Ph Sensitive ◽  
Endolymphatic Sac ◽  
Transport Systems ◽  
Membrane Bound ◽  
The Relationship

The aim of the present work was to assess the effect of various drugs applied locally on the pH of the luminal fluid (pHlum) in guinea pig endolymphatic sac. pHlum and transepithelial potential, when measured in vivo by means of double-barrelled pH-sensitive microelectrodes, were 7.06 ± 0.08 and +6.1 ± 0.34 mV (mean ± SE; n = 84), respectively, which is consistent with a net acid secretion in the luminal fluid of the endolymphatic sac. Bafilomycin and acetazolamide increased and decreased, respectively, pHlum. Amiloride, ethylisopropylamiloride, ouabain, and Schering 28080 had no effect on pHlum. Results obtained with inhibitors of anionic transport systems were inconclusive; e.g., DIDS reduced pHlum, whereas neither SITS nor triflocin had any effect. We conclude that bafilomycin-sensitive H+-ATPase activity accounts for the transepithelial acid gradient measured in the endolymphatic sac and that intracellular and membrane-bound carbonic anhydrase probably participates in regulating endolymphatic sac pHlum. The relationship between acid pH, endolymph volume, and Ménière's disease remains to be further investigated.

Acid secretion in isolated guinea pig colon

1987 ◽  
Vol 253 (2) ◽  
pp. G155-G164 ◽  
Author(s):  
Y. Suzuki ◽  
K. Kaneko
Keyword(s):  
Carbonic Anhydrase ◽  
Guinea Pig ◽  
Acid Secretion ◽  
Proximal Part ◽  
Bathing Solution ◽  
Maximal Effect ◽  
Dose Dependency ◽  
Ussing Chambers ◽  
Mucosal Acidification ◽  
Ph Stat

Isolated guinea pig distal colons secreted acid into the mucosal bathing solution at a rate of 1.0-1.5 mumol X cm-2 X h-1 when the preparations were mounted in Ussing chambers and bathed with HCO3(-)-CO2-free solution. The rates of the acidification and alkalinization of the solutions were measured by a pH stat system or calculated from changes in the pH of the solution. The acid secretion was localized in the middle and distal parts of the colon but absent in the proximal part of the colon and the cecum. The mucosal acidification was accompanied by serosal alkalinization, the rate of the latter being approximately 60% of the former. A carbonic anhydrase inhibitor, methazolamide (10(-4) M), reduced both the mucosal acidification and serosal alkalinization rates by a similar magnitude. The mucosal acidification was completely abolished by mucosal K+-free conditions but unaffected by mucosal Na+-free conditions. Ouabain added to the mucosal solution promptly inhibited the acid secretion. Dose dependency of the inhibition conformed to the Michaelis-Menten equation with a half-maximal effect at 4 X 10(-6) M. When the pH of the mucosal solution was reduced to 4.3, the rate of the mucosal acidification remained essentially the same as that at pH = 7.4. Vanadate (10(-4) M) added to both the mucosal and serosal solutions significantly reduced the mucosal acidification rate. These results suggest that CO2 derived from the epithelial metabolism is hydrated by carbonic anhydrase in the cell and released H+ enters the mucosal solution while HCO3- enters the serosal solution. H+ exit across the mucosal membrane may be mediated by H+-ATPase that is sensitive to ouabain.

The relationship between Mg2+-stimulated ATPase activity and glycogen content in rat liver

1969 ◽  
Vol 47 (3) ◽  
pp. 339-345 ◽  
Author(s):  
B. Rubenstein ◽  
P. G. Scholefield
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Rat Liver ◽  
Glycogen Content ◽  
Phosphorylase Activity ◽  
Tumor Bearing ◽  
Physical Association ◽  
The Relationship

During starvation there is an increase in the ATPase activity of a postmitochondrial fraction of rat liver. The increase is relatively specific for ATP and there is no change in the Na+,K+-stimulated ATPase activity. A corresponding increase in ATPase activity is found on pretreatment of the rat with glucagon and in tumor-bearing animals. The increase has been correlated with increase in phosphorylase activity and decrease in glycogen content under in vivo and in vitro conditions. Treatment of fasted animals with glucose or sucrose restores the glycogen content and diminishes the ATPase activity to normal levels, but puromycin is without effect. It is proposed that a physical association of glycogen with Mg2+-stimulated ATPase activity prevents the enzyme activity from being expressed.

Biochemical, histological, and inhibitor studies of membrane carbonic anhydrase in frog gastric acid secretion

2001 ◽  
Vol 281 (1) ◽  
pp. G61-G68 ◽  
Author(s):  
Erik R. Swenson ◽  
Timothy W. Tewson ◽  
Per J. Wistrand ◽  
Yvonne Ridderstrale ◽  
Chingkuang Tu
Keyword(s):  
Carbonic Anhydrase ◽  
Acid Secretion ◽  
Molecular Mass ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Before And After ◽  
Capillary Endothelial Cells ◽  
Membrane Bound ◽  
Acid Inactivation ◽  
Mucosal Side

Gastric acid secretion is dependent on carbonic anhydrase (CA). To define the role of membrane-bound CA, we used biochemical, histochemical, and pharmacological approaches in the frog ( Rana pipiens). CA activity and inhibition by membrane-permeant and -impermeant agents were studied in stomach homogenates and microsomal fractions. H+secretion in the histamine-stimulated isolated mucosa was measured before and after mucosal addition of a permeant CA inhibitor (methazolamide) and before and after mucosal or serosal addition of two impermeant CA inhibitors of differing molecular mass: a 3,500-kDa polymer linked to aminobenzolamide and p-fluorobenzyl-aminobenzolamide (molecular mass, 454 kDa). Total CA activity of frog gastric mucosa is 2,280 U/g, of which 10% is due to membrane-bound CA. Membrane-bound CA retains detectable activity below pH 4. Histochemically, there is membrane-associated CA in surface epithelial, oxynticopeptic, and capillary endothelial cells. Methazolamide reduced H+secretion by 100%, whereas the two impermeant inhibitors equally blocked secretion by 40% when applied to the mucosal side and by 55% when applied to the serosal side. The presence of membrane-bound CA in frog oxynticopeptic cells and its relative resistance to acid inactivation and inhibition by impermeant inhibitors demonstrate that it subserves acid secretion at both the apical and basolateral sides.

scholarly journals Negative correlation between maorophage proooagulant and migraion ability in the course of inflammation

1996 ◽  
Vol 5 (4) ◽  
pp. 271-275
Author(s):  
I. Vilic ◽  
L. M. Prokic
Keyword(s):  
Cell Migration ◽  
Guinea Pig ◽  
Negative Correlation ◽  
Procoagulant Activity ◽  
Sterile Inflammation ◽  
Migration Ability ◽  
Random Migration ◽  
The Relationship

The importance of macrophage procoagulant activity (PCA) to cell migration is presumed. In this study we assayed the relationship between the two functions in guinea-pig peritoneal resident macrophages and cells elicited by a sterile inflammation induction, which lasted up to 6 days. The findings pointed to anin vivoinduction of PCA in macrophages, which declined with time during inflammation. A clear negative correlation between PCA and random migration ability was demonstrated. Our results suggest that the local induction of coagulation by macrophages may immobilize the cells at the site of inflammation.

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