Modification of frequency augmentation‐potentiation by GTPγS in the frog neuromuscular junction

Cell Biochemistry and Function - Tập 13 Số 2 - Trang 105-109 - 1995
Koh‐ichi Enomoto1, Takashi Maéno1
1Department of Physiology, Shimane Medical University, Izumo, Shimane 693, Japan

Tóm tắt

AbstractThe effect of modifiers of guanine nucleotide‐binding proteins (G proteins) on the frequency augmentation‐potentiation of transmitter release were studied in the frog neuromuscular junction. Using GenetransferR as a carrier the mean quantal content of the endplate potential increased by penetration of GTPγS into the presynaptic nerve terminal. Neither GTPγS alone nor carrier alone had any effect. The relationship of log (mean quantal content) versus stimulation frequency changed from a single linear to a dual linear function, suggesting that the immediately releasable pool was modified. GDPβS + carrier also had similar effects, but was less potent. Aluminium fluoride was without effect. Extracellularly recorded presynaptic nerve action potentials remained unchanged with GTPγS + carrier. Also, GTPγS + carrier did not affect the action potential nor the cytosolic Ca2+ concentration in differentiated NG108–15 hybrid cells. It is suggested that some smg‐type G protein‐dependent processes are involved in determining frequency augmentation‐potentiation.

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Tài liệu tham khảo

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Cell Biochemistry and Function

Tập 13 Số 2

105-109

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