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Hypotonic swelling increases L-type calcium current in smooth muscle cells of the human stomach

Published online by Cambridge University Press:  02 November 2000

Chun Hee Kim
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Poong-Lyul Rhee
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Jong Chul
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Yong-Il Kim
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Insuk So
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Ki Whan Kim
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Myoung Kyu Park
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Dae-Yong Uhm
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
Tong Mook Kang
Affiliation:
Department of Physiology, Medicine and Surgery, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea and Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea
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Abstract

The purpose of the present study was to characterize the Ca2+ channels in smooth muscle cells from human stomach and to examine the effects of osmotic swelling on the channel activity. Ca2+ channel current with either Ca2+ or Ba2+ 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 Ca2+ concentration ([Ca2+]i) were measured by microfluorimetry. The pharmacological and voltage activation profile suggests a typical dihydropyridine-sensitive L-type Ca2+ current. Cell swelling, induced by hypotonic challenge, enhanced the amplitude of currents through L-type Ca2+ channels without significant effects on steady-state voltage dependency. After treatment with the L-type Ca2+ channel agonist Bay K 8644 (0.1-2 µM), no further significant increase in calcium channel current or corresponding [Ca2+]i transients were provoked by the swelling. The above results demonstrated that the presence of L-type Ca2+ 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. Experimental Physiology (2000) 85.5, 497-504.

Type
Research Article
Copyright
© The Physiological Society 2000

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