Human growth hormone releasing factor (hGRF) modulates calcium currents in human growth hormone secreting adenoma cells.
Electrophysiology of human growth hormone secreting tumour cells and its modification by hGRF has been studied using on-cell and Nystatin-perforated whole-cell recording configurations. Local application of hGRF (10 nM) produced an increase in the frequency of action potentials. Ca2+ currents were isolated by a ramp depolarizing pulse from -120 mV to +60 mV in the presence of tetrodotoxin (1 microM). Human GRF increased the Ca2+ currents which could be blocked by Ni+ (300 microM). We conclude that an increase in Ca2+ current is integral to the action of hGRF on these cells.
Chen
C
C
Prince Henry's Institute of Medical Research, Monash Medical Centre, Clayton (Melbourne), Victoria, Australia.
Zhang
J
J
McNeill
P
P
Pullar
M
M
Cummins
J T
JT
Clarke
I J
IJ
D000200:Action Potentials / Q000187:drug effects; D000236:Adenoma / Q000378:metabolism / Q000503:physiopathology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D010911:Pituitary Neoplasms / Q000378:metabolism / Q000503:physiopathology*; D015222:Sodium Channels / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D015220:Calcium Channels; D015222:Sodium Channels; D013779:Tetrodotoxin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone