Am. J. Respir. Cell Mol. Biol.,
Volume 19, Number 5, November, 1998 805-811
Effects of Histamine and Endothelin-1 on Membrane Potentials and Ion
Currents in Bovine Tracheal Smooth-Muscle Cells
Masayuki
Nara,
Tsukasa
Sasaki,
Sanae
Shimura,
Takako
Oshiro,
Toshiya
Irokawa,
Yasunori
Kakuta,
and
Kunio
Shirato
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan
We tested the effects of tetraethylammonium (TEA), acetylcholine (ACh), histamine, and endothelin-1 on
single airway smooth-muscle cells from bovine trachea, using the patch-clamp technique. Resting membrane potential was 
48 ± 1 mV (n = 47). Both TEA and ACh significantly depolarized the membrane,
by +28 ± 4 mV (P < 0.001, n = 12) and +21 ± 2 mV (P < 0.01, n = 7), respectively, in the whole-cell configuration. In contrast, both histamine and endothelin-1 hyperpolarized the membrane, by 21 ± 6 mV (P < 0.01, n = 8) and 15 ± 2 mV (P < 0.01, n = 8), respectively. Calcium-dependent large-conductance K+-channels (127 pS) and small-conductance K+ channels (21 pS) were identified in excised
patches. The small-conductance K+ channel was inhibited by 4-aminopyridine and activated by both histamine and endothelin-1. Furthermore, TEA did not alter the membrane hyperpolarization by these agonists,
suggesting that the small-conductance K+ channel or delayed-rectifier K+ channel was involved in the
membrane hyperpolarization. Membrane hyperpolarization by histamine and endothelin-1 suggests that activation of voltage-dependent calcium channels (VDCCs) or of calcium influx does not contribute substantially to the contractile response of airway smooth-muscle contraction to these agonists.
