Some New Observations on Caffeine-Induced Rhythmic Hyperpolarization in Frog Sympathetic Ganglion Cells.

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概要

• 論文の詳細を見る

• Unstimulated bullfrog sympathetic ganglia were studied in vitro by intracellular and extracellular recording methods. In 80% of the cells impaled with K citrate microelectrodes, caffeine caused initial hyperpolarization (ICH) followed by rhythmic membrane hyperpolarization (RMH). Four different patterns of rhythmicity were observed, the most common being a regular beating pattern. RMH frequency depended on both caffeine and Ca<SUP>2+</SUP> Tetraethylammonium reduced RMH amplitude, but did not affect frequency. Caffeine effects on cyclic AMP are not responsible for RMH since neither dibutyryl cyclic AMP nor phosphodiesterase inhibitors elicited RMH. However, the anion in the microelectrode filling solution is critical to both the incidence and amplitude of RMH, the order of effectiveness being: citrate >>> glutamate, acetate and chloride. In cells impaled by electrodes filled with K thiocyanate or K iodide, caffeine also caused large amplitude hyperpolarizing oscillations of membrane potential, suggesting that the effectiveness of citrate is not due to Ca<SUP>2+</SUP> chelation. High gain extracellular DC recording revealed no sign of caffeine ICH, RMH or any hyperpolarizing effets. The absence of signs of caffeine hyperpolarization with extracellular recording has several interpretations, and these are discussed.

• 公益社団法人 日本薬理学会の論文

著者

• Riker William

  Department of Pharmacology, School of Medicine, L221, The Oregon Health Sciences University

• Somei Kohsuke

  Department of Oral Physiology, School of Dentistry, Iwate Medical University

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• SYNAPTIC FACILITATORY AND DEPRESSANT ACTIONS OF 3, 4-DIAMINOPYRIDINE: CORRELATION WITH ANTICURARE PROPERTIES
• Some New Observations on Caffeine-Induced Rhythmic Hyperpolarization in Frog Sympathetic Ganglion Cells.

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