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Hypotonic Swelling Increases L‐Type Calcium Current in Smooth Muscle Cells of the Human Stomach
Author(s) -
Kim Chun,
Rhee PoongLyul,
Chul Jong,
Kim YongIl,
So Insuk,
Kim Ki,
Park Myoung Kyu,
Uhm DaeYong,
Kang Tong
Publication year - 2000
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1111/j.1469-445x.2000.02013.x
Subject(s) - swelling , dihydropyridine , tonicity , biophysics , patch clamp , chemistry , calcium , intracellular , voltage dependent calcium channel , biochemistry , biology , medicine , pathology , receptor , organic chemistry
The purpose of the present study was to characterize the Ca 2+ channels in smooth muscle cells from human stomach and to examine the effects of osmotic swelling on the channel activity. Ca 2+ channel current with either Ca 2+ or Ba 2+ as charge carrier was recorded from freshly isolated smooth muscle cells using the conventional whole‐cell patch clamp technique. The degree of cell swelling as a result of hypotonic challenge was monitored using a video image analysis system. The changes in intracellular Ca 2+ concentration ([Ca 2+ ] i ) were measured by microfluorimetry. The pharmacological and voltage activation profile suggests a typical dihydropyridine‐sensitive L‐type Ca 2+ current. Cell swelling, induced by hypotonic challenge, enhanced the amplitude of currents through L‐type Ca 2+ channels without significant effects on steady‐state voltage dependency. After treatment with the L‐type Ca 2+ channel agonist Bay K 8644 (0.1‐2 μM), no further significant increase in calcium channel current or corresponding [Ca 2+ ] i transients were provoked by the swelling. The above results demonstrated that the presence of L‐type Ca 2+ current in smooth muscle cells of the human stomach and the augmentation of the current are closely associated with the volume increase resulting from hypotonic swelling.