Differential modulation of pancreatic β‐cell bursting by intracellular pH in the presence and absence of a K‐ATP channel blocker

FEBS Letters

Rosário, Luís M.¹  Salgado, António P.¹  Santos, Rosa M.¹  Barbosa, Rui M.¹ 

[1] Center for Neurosciences of Coimbra, Department of Zoology, University of Coimbra, P-3049 Coimbra, Portugal

关键词: Pancreatic β-cell;    Islet of Langerhans;    Intracellular pH;    Bursting electrical activity;    ATP-dependent K+ channel;    Extracellular Ca2+;    pHi;    intracellular pH;    K-ATP channels;    ATP-dependent K+ channels;    K-Ca channels;    Ca2+-activated K+ channels;    [Ca2+]i;    intracellular free Ca2+ concentration;    BCECF;    2';    7'-bis-carboxyethyl-5(6)-carboxyfluorescein;    BCECF/AM;    acetoxymethyl ester of BCECF;   

DOI  :  10.1016/0014-5793(93)80471-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The study of the influence of intracellular pH (pH_i) changes on the mechanism underlying pancreatic β-cell bursting has been hampered by concomitant effects on the activity of background ATP-dependent K⁺ (K-ATP) channels. β-cells were made to burst in the absence of active K-ATP channels by raising external Ca²⁺ in the presence of 11 mM glucose and tolbutamide. An alkalinizing pH; shift (exposure to 20 mM NH₄C1) increased the burst active phase duration. Conversely, an acidifying shift (NH₄Cl withdrawal) suppressed the electrical activity. This is the mirror image of the effects recorded in the absence of tolbutamide. Glibenclamide and quinine suppressed the alkalinization-evoked hyperpolarization. This study emphasizes the differential sensitivity of different β-cell ion channels to pH_i and the prevalent role of K-ATP channels as electrical transducers of cytoplasmic pH changes under regular physiological conditions.

【 授权许可】

Unknown