Mechanism of the inhibitory action of electric current on H+ secretion by frog gastric mucosa
Kivilaakso, E.; Crass, R.; Allison, J.G.; Ito, S.; Fromm, D.; Silen, W.
Gastroenterology 76(4): 795-803
1979
ISSN/ISBN: 0016-5085 PMID: 33868 Document Number: 145592
The mechanism of the inhibitory action of electric current on gastric H+ secretion was studied using isolated frog gastric mucosa. Electric current, 500 .mu.A/cm2, passed from mucosa to serosa (mucosa positive with respect to serosa), reversibly inhibited net H+ secretion, leading to complete cessation of luminal H+ appearance usually within 1 h. The decrease in luminal H+ appearance was associated with an almost equal decrease in serosal .**GRAPHIC**. appearance. The inhibition of net H+ secretion may be due to decrease in active H+ transport rather than to passive electrochemical back flux of the secreted H+ from the luminal bathing solution. Ultrastructural analysis of the tissues supported this view by demonstrating conversion of oxyntic cells into the resting (non-secreting) morphologic configuration during the passage of current. Blocking of the conductive pathways for K+ in the nutrient (serosal) cell membrane by adding Ba2+ to the serosal bathing solution significantly opposed the inhibitory action of electric current on H+ secretion. When electric current was passed through a mucosal solution containing a high concentration of K+, slight stimulation rather than inhibition of active H+ transport occurred (as judged from serosal .**GRAPHIC**. appearance). In this circumstance, the oxyntic cells retained their active secretory configuration despite the opposing current. Electric current, passed from mucosa to serosa, inhibits active H+ transport by oxyntic cells. The inhibitory action of an opposing current may be accomplished by electrolytic removal of K+ from an intracellular compartment essential for the function of the H+ secretory pump.