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.
Original language | English (US) |
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Pages (from-to) | 497-504 |
Number of pages | 8 |
Journal | Experimental Physiology |
Volume | 85 |
Issue number | 5 |
DOIs | |
State | Published - 2000 |
Externally published | Yes |
ASJC Scopus subject areas
- Physiology
- Nutrition and Dietetics
- Physiology (medical)