Ionic pathways of secretory membrane of frog gastric mucosa in Cl--free media

1976 ◽  
Vol 231 (6) ◽  
pp. 1649-1654 ◽  
Author(s):  
TL Holloman ◽  
M Schwartz ◽  
MA Dinno ◽  
G Carrasquer
Keyword(s):  
Gastric Mucosa ◽  
Secretory Rate ◽  
Lower Resistance ◽  
Free Media

Experiments were performed to determine the return ionic pathways of the secretory membrane of frog gastric mucosa associated with the electrogenic H+ pump in Cl--free media. The replacement of a 52 mM Na2SO4 secretory solution with a 52 mM K2SO4 secretory solution led to a decrease of resistance, an increase of the H+ secretory rate, and a reversal of the PD. The replacement of 52 mM Na2SO4 with 52 mM MgSO4 led to an increase of resistance and a decrease of the H+ rate. These results provided evidence for the existence of K+ and Na+ pathways, the former having a lower resistance than the latter. Short-circuiting the mucosa in Mg2+ solutions increased the H+ rate to the value in Na+ solutions, hence ruling out the possibility that Mg2+ might interfere with the H+ pump. The fact that the Mg2+ secretory solution, without K+ or Na+, did not abolish the H+ rate suggested the presence of at least a third ionic pathway. presumably SO42-, providing that Mg2+ does not penetrate the mucosa.

Inhibition of H+ secretion in the frog gastric mucosa by ATP and related compounds

1976 ◽  
Vol 230 (6) ◽  
pp. 1688-1694 ◽  
Author(s):  
SS Sanders ◽  
CF Butler ◽  
J O'Callaghan ◽  
WS Rehm
Keyword(s):  
Gastric Mucosa ◽  
Rana Pipiens ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Threshold Concentration ◽  
Maximal Inhibition ◽  
Secretory Rate ◽  
Free Media ◽  
Related Compounds

Addition of adenosine triphosphate (ATP) to the nutrient (submucosal-facing) solution of the histamine-stimulated in vitro frog (Rana pipiens) gastric mucosa produces a marked reduction in the H+ secretory rate and an increase in transmucosal potential difference (PD) and resistance in both Cl- and Cl-free media. The effects are reversible upon removal of ATP. The threshold concentration is between 1 and 2 mM, and 5 mM produce maximal inhibition. It is shown that the effects of ATP are not due to a change in pH or osmolarity of the nutrient fluid, or to a decrease in the Ca2+ and/or Mg2+ activities of the nutrient fluid. It is also shown that the inhibitory action of ATP is not dependent on a chelation complex between Ca2+ or Mg2+. Adenosine diphosphate also produces effects essentially the same as ATP whereas 5'-adenosine monophosphate and adenosine produce relatively little or no change.

Uptake of K+ by frog gastric mucosa from submucosal side and acid secretory rate.

1977 ◽  
Vol 232 (3) ◽  
pp. E294
Author(s):  
N Takeguchi ◽  
I Horikoshi ◽  
M Hattori
Keyword(s):  
Gastric Mucosa ◽  
Linear Relation ◽  
Secretory Rate ◽  
Co2 Gas ◽  
Control Value ◽  
Different Types ◽  
K Concentration ◽  
Mucosal Side ◽  
External K

The K+ content in frog gastric mucosa (K+) was measured as a function of the submucosal K+ concentration ([K+sm]) in the absence of K+ on the mucosal side. The (K+) in HCO3- buffer with 95% O2-5% CO2 gas showed that the removal of external K+ induced a 27% K+ loss from the control value of 5 mM K+sm, that there was no linear relation between (K+) and [K+sm, and that the change in the (K+) versus the [K+sm] was hyperbolic, indicating that there are two different types of K+ in the mucosa: bound and free K+.

Oxygenation of frog gastric mucosa in vitro

1975 ◽  
Vol 229 (6) ◽  
pp. 1510-1513 ◽  
Author(s):  
GW Kidder ◽  
CW Montgomery
Keyword(s):  
Oxygen Consumption ◽  
Gastric Mucosa ◽  
Acid Secretion ◽  
Normal Pressure ◽  
Bathing Solution ◽  
Hyperbaric Chamber ◽  
Secretory Rate ◽  
Co2 Diffusion ◽  
Rate Of Oxygen Consumption

We have recently shown that 5% CO2/95% O2 in the serosal bathing solution, with 100% O2 in the mucosal solution, results in CO2-diffusion limitation of acid secretion in bullfrog gastric mucosa. Changing to 10% CO2/90% 02 on both surfaces doubles the acid secretory rate. We calculate that, were the rate of oxygen consumption to increase significantly as a result of secretory stimulation, the tissue would now be oxygen limited. This prediction is tested by raising the P02 by increasing the total pressure in a hyperbaric chamber. Since no change in acid secretory rate or potential difference was observed upon changing from PO2 = 0.9 to PO2 = 1.9 atm, we conclude that the tissue is not O2 limited at normal pressure. Decreasing PO2 below 0.9 atm, by contrast, decreases the acid secretory rate and raises both PD and resistance. We infer that the rate of oxygen consumption did not rise significantly when acid secretion was increased by supplying sufficient CO2.

Effect of potassium on secretion and potential of frog's gastric mucosa in Cl–-free solutions

1963 ◽  
Vol 205 (5) ◽  
pp. 873-877 ◽  
Author(s):  
T. L. Davis ◽  
J. R. Rutledge ◽  
W. S. Rehm
Keyword(s):  
Gastric Mucosa ◽  
Potential Difference ◽  
Secretory Rate ◽  
Voltage Clamping ◽  
Bathing Fluid

In previous work it was shown that the potential difference of the secreting mucosa bathed in Cl–-free solutions (SO4– replacing Cl–) is negative (nutrient side negative). In the present work it was found that an increase of the K+ concentration (K+ substituted for Na+) of the bathing fluid on the secretory side produced an increase in H+ secretory rate. The effect of voltage-clamping at zero and at +100 mv on the H+ rate, with various K+ concentrations in the bathing fluids, yielded results predicted by the electrogenic H+ theory, but not by a forced exchange concept.

Inhibition of gastric H+ secretion, K+-ATPase and K+-phosphatase by estradiol in vivo and in vitro

1982 ◽  
Vol 60 (5) ◽  
pp. 680-684 ◽  
Author(s):  
L. Limlomwongse ◽  
P. Piyachaturawat
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Enzyme Activities ◽  
Direct Action ◽  
Inhibitory Effect ◽  
Secretory Rate ◽  
Dose Dependent

The effect of estrogen on the gastric acid secretion and H+-transporting enzymes, K+ -ATPase and K+-phosphatase, were investigated in the rat. The maximum H+ secretory rate in response to 1 mM histamine was significantly reduced (P < 0.05) in both the isolated gastric mucosa obtained from the rats treated with estradiol in vivo for 7 days and the mucosa directly incubated in vitro with estradiol. The inhibitory effect on the gastric enzyme activities in vitro showed a dose-dependent pattern of a noncompetitive type. The result suggested that estradiol may have a direct action on the gastric H+ secretion by inhibiting the H+ transport enzyme activities.

Effects of increased O2 and CO2 on acid secretion by dogfish gastric mucosa in vitro

1976 ◽  
Vol 231 (4) ◽  
pp. 1240-1245 ◽  
Author(s):  
Kidder GW
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Squalus Acanthias ◽  
Transepithelial Resistance ◽  
O2 Consumption ◽  
Hyperbaric Chamber ◽  
Secretory Rate ◽  
Co2 Diffusion ◽  
Hyperbaric Conditions

The gastric mucosa of the dogfish (Squalus acanthias), as usually prepared for in vitro chambered experiments, shows a secretory rate (JH) of about 2 mueq/cm2-h, but a potential difference (PD) of zero. Raising PCO2 from 0.05 to 0.1 atm increases JH by 40% and causes the development of a PD of about 2 mV, mucosal surface positive. Increasing PO2 from 0.9 to 1.9 atm in a hyperbaric chamber (at constant PCO2 = 0.1 atm) doubles JH and increases PD to 5 mV. Transepithelial resistance falls by 20% at high PO2. It appears that the dogfish gastric mucosa, like that of the frog, is rate limited by CO2 diffusion into the tissue from the usual 5% mixture and is also rate limited by the usual O2 levels (unlike the frog), presumably due to its thicker structure and higher O2 consumption. The mucosal-positive PD, which is reversed from all other mucosae studied, is readily explained by separate electrogenic H+ and Cl- pumps, but less readily by schemes embodying a neutral HCl pump. It is not yet known whether the hyperbaric conditions are sufficient to ensure O2 sufficiency.

Effects of Ethacrynic Acid on Frog Gastric Mucosa in Chloride Solutions

1974 ◽  
Vol 52 (2) ◽  
pp. 166-173
Author(s):  
Mumtaz A. Dinno ◽  
Manuel Schwartz ◽  
Axel K. Olson ◽  
Gaspar Carrasquer
Keyword(s):  
Gastric Mucosa ◽  
Nutrient Solution ◽  
Ethacrynic Acid ◽  
Secretory Rate ◽  
High K ◽  
Solution Bathing ◽  
Transmembrane Potential Difference ◽  
Low K ◽  
Nutrient Solutions

The addition of ethacrynic acid to a concentration of 1 mM in the nutrient solution bathing the frog gastric mucosa in vitro produced an immediate decrease in resistance followed by an increase in resistance and a decrease in H+ secretory rate. The latter effect was irreversible and the former reversible. During the initial phase for nutrient solutions of 4 mM K+ and 79 mM K+ containing 1 mM ethacrynic acid, the decrease in resistance was about 30% and the decrease in the transmembrane potential difference (P.D.) was about 1 mV in the low K+ case and 2 mV in the high K+ case. The addition of ethacrynic acid to a 4 mM K+ nutrient solution containing 1 mM Ba2+ produced initially a 19% decrease in resistance and both positive and negative changes in P.D. In the absence of Ba2+, these results suggest strongly a marked increase of K+ permeability with the possibility of some increase of Cl− permeability. In the presence of Ba2+, as a result due to the increased K+ resistance of the nutrient membrane, ethacrynic acid may affect predominantly either K+ or Cl− permeability.

Acid secretion, potential, and resistance of frog stomach in K+-free solutions

1965 ◽  
Vol 209 (1) ◽  
pp. 146-152 ◽  
Author(s):  
T. L. Davis ◽  
J. R. Rutledge ◽  
D. C. Keesee ◽  
F. J. Bajandas ◽  
W. S. Rehm
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Electrical Resistance ◽  
Transient Increase ◽  
Potential Difference ◽  
Secretory Rate ◽  
Frog Stomach ◽  
Voltage Clamping

The removal of K+ from the fluids bathing the in vitro frog gastric mucosa results in a decrease of the H+ secretory rate to zero, a marked increase in electrical resistance, a transient increase in potential difference (PD), and relatively little change in the K+ content of the mucosa. The effects of K+ removal are reversed by adding K+ either to the nutrient fluid (4 mm) or to the secretory fluid (104 mm). They are not reversed by voltage clamping (nutrient positive). Following the cessation of H+ secretion, the PD gradually decreases to a level that is low but still greater than zero. The PD under these conditions can be reversibly reduced to about zero by anoxia. It is concluded that the presence of K+ in certain regions of the mucosa is necessary for the functioning of the H+ and Cl– mechanisms.

Acid secretion, potential difference, and resistance of elasmobranch stomach

1962 ◽  
Vol 203 (6) ◽  
pp. 1091-1093 ◽  
Author(s):  
Warren S. Rehm
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Present Report ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Potential Difference ◽  
Secretory Rate ◽  
Negaprion Brevirostris ◽  
Ion Secretion

The present report is concerned with in vitro studies on gastric mucosa of the skate, Raja eglentaria, the electric ray, Narcine braziliensis, and the shark, Negaprion brevirostris. Maximum secretory rates of from 0.65 to 2.7 µEq hr–1 cm–2 were found. An increase in the secretory rate from an initial low level was associated with an increase in potential difference (PD), a decrease in resistance, and an increase in the calculated short-circuit current. The average PD and resistance before the increase in the secretory rate was 2.2 mv (nutrient positive) and 268 ohms cm2. After the increase they were 6.4 mv and 199 ohms cm2. Thiocyanate (10–2 m) to nutrient resulted in a decrease of secretory rate to zero and an increase in PD and resistance. The results can be explained on the basis of the separate mechanisms theory of H+ and Cl– ion secretion on the assumption that the resistance in the Cl– ion limb of the circuit is considerably lower than that in the H+ ion limb of the circuit.

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