T. Dsouza et Se. Dryer, EFFECTS OF PHOSPHODIESTERASE INHIBITORS AND FORSKOLIN ON CYCLIC GMP-ACTIVATED CHANNELS IN INTACT ISOLATED CELLS OF THE CHICK PINEAL-GLAND, Neurochemistry international, 27(6), 1995, pp. 527-533
Application of the phosphodiesterase inhibitors isobutylmethylxanthine
(100 mu M) caused activation of low-conductance cationic channels in
intact acutely-isolated chick pineal cells. This effect required conti
nued contact between the cytoplasmic face of the patch membrane and th
e cytoplasm. The biophysical properties of the channels were identical
to those of cyclic GMP-activated channels described previously in exc
ised patches. Application of 40 mu M forskolin did not cause activatio
n of the low-conductance channels. A second population of spontaneousl
y active large-conductance cationic channels was observed in some patc
hes. Gating of large-conductance channels was not affected by phosphod
iesterase inhibitors of forskolin. These results support the theory th
at phototransduction cascades similar to those of the vertebrate retin
a are also present in chick pineal cells.