title: K+ -stimulated Na+ transport in frog-skin epithelia.
abstract: Increasing [K+] from 2.5 mmol/l to 115 mmol/l on the serosal side of the frog skin produces a rapid decrease of short-circuit current (Isc) that is followed, within a few minutes, by a recovery of Isc to near or above its control value. After isolation of the epithelium by a procedure involving collagenase treatment and physical removal of the corium, increasing serosal [K+] still produced a depression of Isc but no significant recovery phase. By itself, collagenase treatment reduced but did not eliminate the recovery phase. The recovery phase was also markedly depressed by the beta-adrenergic blocker oxprenolol, but not by propranolol, atropine or indomethacin. Amiloride, given during the recovery phase, caused Isc to reverse to a small outward value. These results suggest that the recovery phase of Isc seen in the response to increased serosal [K+] represents an increase in Na+ influx through amiloride-sensitive channels which is triggered by the release of an intermediary agent, possibly a beta-adrenergic agonist, from some structure in the corium.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004848:Epithelium / Q000378:metabolism; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008564:Membrane Potentials; D011188:Potassium / Q000494:pharmacology*; D011892:Rana catesbeiana; D012867:Skin / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
chemical_list: D000319:Adrenergic beta-Antagonists; D000584:Amiloride; D012964:Sodium; D011188:Potassium; D007213:Indomethacin