A functional role of the erg-like inward-rectifying K+ current in prolactin secretion from rat lactotrophs.
The functional role of the inward-rectifying erg-like K+ current in rat lactotrophs was studied by the use of a selective blocker, the class III antiarrhythmic agent E-4031. The erg-like current was measured as drug-sensitive current in physiological K+ gradient. In the range of the normal resting membrane potential of rat lactotrophs (around -45 mV) the erg-like current constituted a steady outward current. A selective block of this current by E-4031 resulted in a moderate (5 mV) depolarization of the membrane potential in 64% of the lactotroph cells. Measurements of basal prolactin secretion with the reverse hemolytic plaque assay showed that the number of prolactin secreting cells and the amount of prolactin secreted from single lactotrophs was significantly increased in the presence of E-4031. The data show that the contribution of the erg-like K+ current to the maintenance of the resting membrane potential is functionally important for the regulation of prolactin secretion.
Bauer
C K
CK
Physiologisches Institut, Abteilung für angewandte Physiologie, Universitätskrankenhaus Eppendorf, Hamburg, Germany. c.bauer@uke.uni-hamburg.de
Schäfer
R
R
Schiemann
D
D
Reid
G
G
Hanganu
I
I
Schwarz
J R
JR
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D002478:Cells, Cultured; D018999:Charybdotoxin / Q000494:pharmacology; D005260:Female; D007774:Lactation / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology*; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying; D011388:Prolactin / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D000889:Anti-Arrhythmia Agents; D015220:Calcium Channels; D010880:Piperidines; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011725:Pyridines; C063968:E 4031; D018999:Charybdotoxin; D011388:Prolactin