Potential difference responses to nutrient K+, Cl- and Na+ changes in secreting and resting states of frog stomach.
The effects of changes in nutrient concentrations of K+, Cl- and Na+ on the transmucosal potential difference (PD) and the resistance were compared for secreting fundus and resting fundus of Rana pipiens. Increase of K+ from 4 to 40 mM, decrease of Cl- from 81 to 8.1 mM and decrease of Na+ from 102 to 10 mM gave, 10 min after the change in the secreting fundus, delta PD values of -28.2, -19.8 and -7.5 mV, respectively. In the resting fundus with SCN- inhibition, the same changes in nutrient ion concentration gave delta PD values of -20.1, -17.0 and -10.2 mV, respectively. Changes in Na+ concentration were considered in a set of experiments of high acid secreting stomachs (4 to 6 mu equiv. . h-1 . cm-2). Here, delta PD gave for 10-fold decreases in Na+ concentration in secreting fundus -4.8 mV and in resting fundus with SCN- inhibition -22.6 mV. Omeprazole inhibition gave results quite similar to those with SCN- inhibition. From these results in going from secretion to inhibition, it follows that the increment of K+ conductance if it increased was lower than the increase in NaCl symport conductance since the change in delta PD for K+ decreased and that for Na+ increased. Also HCO3- conductance increased with inhibition. After SCN- inhibition the transmucosal resistance initially increased and later decreased. The decrease can be accounted for by the increase in conductance of the NaCl symport pathway and of the HCO3- pathway.
Schwartz
M
M
University of Louisville, Department of Physics, KY 40292.
Carrasquer
G
G
Rehm
W S
WS
Dinno
M A
MA
D000818:Animals; D002712:Chlorides / Q000494:pharmacology*; D002927:Cimetidine / Q000494:pharmacology; D004553:Electric Conductivity; D005744:Gastric Acid / Q000378:metabolism; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009853:Omeprazole / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011894:Rana pipiens; D012964:Sodium / Q000494:pharmacology*; D013861:Thiocyanates / Q000494:pharmacology
D002712:Chlorides; D013861:Thiocyanates; D002927:Cimetidine; D012964:Sodium; D009853:Omeprazole; C031760:thiocyanate; D011188:Potassium