Vasoactive intestinal peptide activates Ca2(+)-dependent K+ channels through a cAMP pathway in mouse lacrimal cells.
The action of vasoactive intestinal peptide (VIP) on Ca2(+)-dependent K+ currents, in dissociated mouse lacrimal cells, was investigated using patch clamp techniques. In whole cell recordings, VIP (10-100 pM) increased the magnitude of the Ca2(+)-dependent K+ current. In single channel recordings, VIP increased the fraction of time the large charybdotoxin-sensitive Ca2(+)-activated K+ channel spent in the open state. The activity of this channel was also increased by adding forskolin or 8-bromo cAMP to the bath. Additionally, application of either cAMP or catalytic subunit of cAMP-dependent protein kinase directly to the cytoplasmic surface of excised inside out patches reversibly lengthened the time Ca2(+)-activated K+ channels spent in the open state. These data suggest that VIP stimulates Ca2(+)-activated K+ channels by a cAMP-dependent pathway in mouse lacrimal acinar cells.
Lechleiter
J D
JD
Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
Dartt
D A
DA
Brehm
P
P
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002469:Cell Separation; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology / Q000502:physiology*; D066298:In Vitro Techniques; D007765:Lacrimal Apparatus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008808:Mice, Inbred CBA; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D015221:Potassium Channels; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D014660:Vasoactive Intestinal Peptide; D000242:Cyclic AMP; D002118:Calcium