P-C1-31 Na+-Ca+2 exchange in the visceral smooth muscle cells

The Ca2+ pump in the plasma membrane plays a key role in the fine control of the cytoplasmic free Ca2+ concentration. In the present study, its subcellular localization was examined with immunocytochemical techniques using a specific antibody generated against the erythrocyte membrane Ca2+ pump ATPase. By immunofluorescence microscopy of cultured cells, the labeling with the antibody was seen as numerous small dots, often distributed in linear arrays or along cell edges. Immunogold EM of cryosections revealed that the dots correspond to caveolae, or smooth invaginations of the plasma membrane. The same technique applied to mouse tissues in vivo showed that the Ca2+ pump is similarly localized in caveolae of endothelial cells, smooth muscle cells, cardiac muscle cells, epidermal keratinocytes and mesothelial cells. By quantitative analysis of the immunogold labeling, the Ca2+ pump in capillary endothelial cells and visceral smooth muscle cells was found to be concentrated 18-25-fold in the caveolar membrane compared with the noncaveolar portion of the plasma membrane. In renal tubular and small intestinal epithelial cells, which have been known to contain the Ca2+ pump but do not have many caveolae, most of the labeling was randomly distributed in the basolateral plasma membrane, although caveolae were also positively labeled. The results demonstrate that the caveolae in various cells has the plasmalemmal Ca2+ pump as a common constituent. In conjunction with our recent finding that an inositol 1,4,5-trisphosphate receptor-like protein exists in the caveolae (Fujimoto, T., S. Nakade, A. Miyawaki, K. Mikoshiba, and K. Ogawa. 1992. J. Cell Biol. 119:1507-1513), it is inferred that the smooth plasmalemmal invagination is an apparatus specialized for Ca2+ intake and extrusion from the cytoplasm.

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The SM 22 promoter directs tissue-specific expression in arterial but not in venous or visceral smooth muscle cells in transgenic mice

Development ◽

10.1242/dev.122.8.2415 ◽

1996 ◽

Vol 122 (8) ◽

pp. 2415-2425 ◽

Cited By ~ 1

Author(s):

H. Moessler ◽

M. Mericskay ◽

Z. Li ◽

S. Nagl ◽

D. Paulin ◽

...

Keyword(s):

Smooth Muscle ◽

Transgenic Mice ◽

Smooth Muscle Cells ◽

Transcriptional Activity ◽

Vascular System ◽

Smooth Muscles ◽

Muscle Cells ◽

Specific Expression ◽

Visceral Muscles ◽

Visceral Smooth Muscle

The transcriptional signals underlying smooth muscle differentiation are currently unknown. We report here the complete sequence and characterization of the single mouse gene for the smooth muscle-specific protein SM 22 and the transcriptional activity of its promoter in cultured smooth muscle cells in vitro and in transgenic mice. In the transgenic animals, promoter constructs ranging in length from 445 to 2126 bp directed reporter expression initially in the heart and the somites of embryos and subsequently in the arteries of the vascular system, but in none of the visceral muscles, nor in the veins. Expression in the heart was spatially restricted to the presumptive right ventricle and outflow tract and disappeared in the adult. Likewise, expression in the somites was only transitory and was not observed after about 14.5 days post coitum in the embryo. In the adult mouse, SM 22 promoter activity persisted in the smooth muscle cells of the arteries and was still notably absent from other smooth muscles, despite the ubiquitous presence of the endogenous SM 22 protein. These findings on the transcriptional activity of a smooth muscle promoter in vivo reveal the existence of different differentiation programmes for smooth muscle cells in the veins and the arteries and raise the expectation of a further subdivision of programmes among the visceral muscles.

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Calcium channel modulation by the dihydropyridine derivative bay K 8644 in mammalian visceral smooth muscle cells

Comparative Biochemistry and Physiology Part C Comparative Pharmacology ◽

10.1016/0742-8413(88)90142-9 ◽

1988 ◽

Vol 89 (1) ◽

pp. 39-43 ◽

Cited By ~ 4

Author(s):

Masami Yoshino ◽

Akihiko Nishio ◽

Hideyo Yabu

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Calcium Channel ◽

Muscle Cells ◽

Bay K 8644 ◽

Channel Modulation ◽

Dihydropyridine Derivative ◽

Visceral Smooth Muscle

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Calcium action potentials in single freshly isolated smooth muscle cells

AJP Cell Physiology ◽

10.1152/ajpcell.1980.239.5.c162 ◽

1980 ◽

Vol 239 (5) ◽

pp. C162-C174 ◽

Cited By ~ 62

Author(s):

J. V. Walsh ◽

J. J. Singer

Keyword(s):

Smooth Muscle ◽

Action Potential ◽

Smooth Muscle Cells ◽

Action Potentials ◽

Maximum Rate ◽

Muscle Cells ◽

Membrane Resistance ◽

Inward Current ◽

Visceral Smooth Muscle ◽

Maximum Rate Of Rise

The ionic basis of the action potential was investigated using intracellular microelectrodes in single smooth muscle cells freshly isolated from the stomach of the toad Bufo marinus. When [Ca2+]0 was elevated (> 8mM), action potentials were readily elicited, which had similar characteristics to those found in many tissue preparations of visceral smooth muscle. There was a decrease in membrane resistance at the peak of the action potential and during the undershoot. The following evidence indicated that the inward current is carried by Ca2+: 1) Raising [Ca2+]0 from 15 to 49.6 mM in the presence of 18.2 mM tetraethylammonium chloride (TEA) increased the maximum rate of rise and the overshoot amplitude, the latter by 15 mV, i.e., 29.5 mV/10-fold change in [Ca2+]0. Changing [Na2+]0 from 11.8 to 81.8 mM had no significant effect on the maximum rate of rise or the overshoot. 2) The action potentials were blocked by 8 mM Mn2+ ([Ca2+]0 = 14.6 mM) but not by 14.3 microM tetrodotoxin (TTX) ([Na2+]0 = 100 mM). 3) Action potentials could be elicited when [Ba2+]0 or [Sr2+]0 were present in high concentrations ([Ca2+]0 less than or equal to 31 microM,[Na2+]0 = 11.8 mM). Both the maximum rate of rise and overshoot amplitude of the action potential increased as the membrane potential became more negative, suggesting increased activation of the inward current. Both TEA and Ba2+ prolonged the action potential, suggesting that a K+ current is responsible for repolarization. Action potentials could also be elicited on anode break at elevated [K+]0 (91 mM).

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Physiological Features of Visceral Smooth Muscle Cells, With Special Reference to Receptors and Ion Channels

Physiological Reviews ◽

10.1152/physrev.1998.78.3.811 ◽

1998 ◽

Vol 78 (3) ◽

pp. 811-920 ◽

Cited By ~ 163

Author(s):

H. KURIYAMA ◽

K. KITAMURA ◽

T. ITOH ◽

R. INOUE

Keyword(s):

Smooth Muscle ◽

Ion Channels ◽

Patch Clamp ◽

Smooth Muscle Cells ◽

Special Reference ◽

Muscle Cells ◽

Relaxation Cycle ◽

Visceral Smooth Muscle ◽

Work Done ◽

The Way

Kuriyama, H., K. Kitamura, T. Itoh, and R. Inoue. Physiological Features of Visceral Smooth Muscle Cells, With Special Reference to Receptors and Ion Channels. Physiol. Rev. 78: 811–920, 1998. — Visceral smooth muscle cells (VSMC) play an essential role, through changes in their contraction-relaxation cycle, in the maintenance of homeostasis in biological systems. The features of these cells differ markedly by tissue and by species; moreover, there are often regional differences within a given tissue. The biophysical features used to investigate ion channels in VSMC have progressed from the original extracellular recording methods (large electrode, single or double sucrose gap methods), to the intracellular (microelectrode) recording method, and then to methods for recording from membrane fractions (patch-clamp, including cell-attached patch-clamp, methods). Remarkable advances are now being made thanks to the application of these more modern biophysical procedures and to the development of techniques in molecular biology. Even so, we still have much to learn about the physiological features of these channels and about their contribution to the activity of both cell and tissue. In this review, we take a detailed look at ion channels in VSMC and at receptor-operated ion channels in particular; we look at their interaction with the contraction-relaxation cycle in individual VSMC and especially at the way in which their activity is related to Ca2+ movements and Ca2+ homeostasis in the cell. In sections ii and iii, we discuss research findings mainly derived from the use of the microelectrode, although we also introduce work done using the patch-clamp procedure. These sections cover work on the electrical activity of VSMC membranes (sect. ii) and on neuromuscular transmission (sect. iii). In sections iv and v, we discuss work done, using the patch-clamp procedure, on individual ion channels (Na+, Ca2+, K+, and Cl−; sect. iv) and on various types of receptor-operated ion channels (with or without coupled GTP-binding proteins and voltage dependent and independent; sect. v). In sect. vi, we look at work done on the role of Ca2+ in VSMC using the patch-clamp procedure, biochemical procedures, measurements of Ca2+ transients, and Ca2+ sensitivity of contractile proteins of VSMC. We discuss the way in which Ca2+ mobilization occurs after membrane activation (Ca2+ influx and efflux through the surface membrane, Ca2+ release from and uptake into the sarcoplasmic reticulum, and dynamic changes in Ca2+ within the cytosol). In this article, we make only limited reference to vascular smooth muscle research, since we reviewed the features of ion channels in vascular tissues only recently.

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Roles of LRRC26 as an auxiliary γ1-subunit of large-conductance Ca2+-activated K+ channels in bronchial smooth muscle cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00331.2019 ◽

2020 ◽

Vol 318 (2) ◽

pp. L366-L375 ◽

Cited By ~ 3

Author(s):

Sayuri Noda ◽

Yoshiaki Suzuki ◽

Hisao Yamamura ◽

Wayne R. Giles ◽

Yuji Imaizumi

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Expression Patterns ◽

Muscle Cells ◽

Bk Channel ◽

Hek293 Cells ◽

Resting Membrane Potential ◽

Channel Activity ◽

Voltage Range ◽

Visceral Smooth Muscle

In visceral smooth muscle cells (SMCs), the large-conductance Ca2+-activated K+ (BK) channel is one of the key elements underlying a negative feedback mechanism that is essential for the regulation of intracellular Ca2+ concentration. Although leucine-rich repeat-containing (LRRC) proteins have been identified as novel auxiliary γ-subunits of the BK channel (BKγ) in several cell types, its physiological roles in SMCs are unclear. The BKγ expression patterns in selected SM tissues were examined using real-time PCR analyses and Western blotting. The functional contribution of BKγ1 to BK channel activity was examined by whole cell patch-clamp in SMCs and heterologous expression systems. BKγ1 expression in mouse bronchial SMCs (mBSMCs) was higher than in other several SMC types. Coimmunoprecipitation and total internal reflection fluorescence imaging analyses revealed molecular interaction between BKα and BKγ1 in mBSMCs. Under voltage-clamp, steady-state activation of BK channel currents at pCa 8.0 in mBSMCs occurred in a voltage range comparable to that of reconstituted BKα/BKγ1 complex. However, this range was much more negative than in mouse aortic SMCs (mASMCs) or in HEK293 cells expressing BKα alone and β-subunit (BKβ1). Mallotoxin, a selective activator of BK channel that lacks BKγ1, dose-dependently activated BK currents in mASMCs but not in mBSMCs. The abundant expression of BKγ1 in mBSMCs extensively facilitates BK channel activity to keep the resting membrane potential at negative values and prevents contraction under physiological conditions.

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