The chloride-stimulated K(+)-secretion by insect midgut and its modification in the presence of osmotic gradients: a short-circuit current and noise-analysis study.
K(+)-secretion in the midgut of the larval moth, Manduca sexta, was studied by measuring the kinetics of the lumen-directed short-circuit current (Isc) and the conduction noise from basolateral K+ channel block by Ba2+. Hemolymph chloride as well as hypotonicity both stimulate this K+ current (IK). The kinetic nature of the stimulation is, however, different in each case. Analysis of blocker noise supports, to a large degree, the interpretation obtained from kinetics, namely: chloride ions do not act via changes in cell volume but influence ion turnover and channel number.
Zeiske
W
W
Institut für Tierphysiologie und Angewandte Zoologie, Freien Universität Berlin, FRG.
Alpert
G
G
Marin
H
H
D000818:Animals; D002712:Chlorides / Q000494:pharmacology*; D004064:Digestive System / Q000187:drug effects / Q000378:metabolism*; D007313:Insecta / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism*
D002712:Chlorides; D007473:Ion Channels; D011188:Potassium