Selective block by glyceryl nonivamide of inwardly rectifying K+ current in rat anterior pituitary GH3 cells.
The effects of glyceryl nonivamide (GLNVA) on ionic currents were compared and examined in rat pituitary GH3 cells. Hyperpolarization-activated K+ currents in GH3 cells bathed in high-K+ Ca2+-free external solution were studied to assess effects of GLNVA on the an inwardly rectifying K+ current (I(K(IR))). GLNVA is very potent in blocking I(K(IR)) in a concentration-dependent manner, with a half maximal concentrations of 0.1 microM. The complete block of I(K(IR)) achieved with concentrations > or = 1 microM revealed the presence of a non-inactivating current. We also found that GLNVA at a concentration above 30 microM inhibited L-type voltage-dependent Ca2+ current and two components of K+ outward currents, while GLNVA (< or = 3 microM) did not have any effect on them. This study shows that GLNVA, in addition to retaining the capability of eliciting peptidergic neurons, is a selective block of I(K(IR)) in GH3 cells and will provide a useful tool for characterizing I(K(IR)) and understanding its physiological function. In addition, the carefulness should be taken about the interpretation of GLNVA-mediated responses in vivo or in vitro.
Wu
S N
SN
Department of Medical Education and Research, Veterans General Hospital-Kaohsiung, Taiwan. snwu@isca.vghks.gov.tw
Li
H F
HF
Jan
C R
CR
Chen
I J
IJ
Lo
Y C
YC
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002460:Cell Line; D004594:Electrophysiology; D005990:Glycerol / Q000031:analogs & derivatives* / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D026902:Potassium Channel Blockers; D051381:Rats
D015220:Calcium Channels; D026902:Potassium Channel Blockers; C080418:N-(4-O-glycerol-3-methoxybenzyl)nonivamide; D005990:Glycerol; D002211:Capsaicin