Length-tension relations of in vitro urinary bladder smooth muscle strips

Urinary bladder smooth muscle (UBSM) generates spontaneous electrical activities due to stochastic nature of purinergic neurotransmitter release from the parasympathetic nerve. The stochastic nature of the purinergic neurotransmitter release was represented by a simplified ‘point-conductance’ model to mimic in vitro-like electrical activities in UBSM cell. The point-conductance was represented by the independent synaptic conductance described by the stochastic random-walk processes and injected into a single-compartment model of mouse UBSM cell. This model successfully evoked irregular spontaneous depolarizations (SDs) and spontaneous action potential (sAP) as the properties of in vitro-like electrical activities in UBSM cells. The model mimics the T- and L-type Ca2+ ion channel blocker by setting their respective conductance to zero. We also found that the point-conductance model modulates the sAP properties by adding background activity.

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Generation of a cell line with smooth muscle phenotype from hypertrophied urinary bladder

AJP Cell Physiology ◽

10.1152/ajpcell.00002.2002 ◽

2002 ◽

Vol 283 (1) ◽

pp. C373-C382 ◽

Cited By ~ 18

Author(s):

Yongmu Zheng ◽

Wilfried T. Weber ◽

Shuqin Wang ◽

Alan J. Wein ◽

Stephen A. Zderic ◽

...

Keyword(s):

Smooth Muscle ◽

Urinary Bladder ◽

Cell Line ◽

Muscarinic Agonist ◽

Bladder Smooth Muscle ◽

Homogeneous Population ◽

Amino Terminal ◽

Urinary Bladder Smooth Muscle ◽

A Cell

We have established a cell line from hypertrophied rabbit urinary bladder smooth muscle (SM) that stably expresses SM myosin (SMM). These cells, termed BSM, are spindle shaped and form swirls, similar to the “hills and valleys” described for cultured aortic SM cells. Western blotting revealed that BSM expresses the amino-terminal SMM heavy chain isoform SM-B, the carboxy-terminal SM1 and SM2 isoforms, and SM α-actin. In addition, they express cGMP-dependent protein kinase G, made by contractile SM cells in vitro but not by noncontractile cells synthesizing extracellular matrix. Immunofluorescence studies indicate a homogeneous population of cells expressing α-actin and SMM, including the SM-B isoform, and karyotyping demonstrates a stable 4N chromosomal pattern. These cells also express calcium-dependent myosin light chain kinase and phosphatase activity and contract in response to the muscarinic agonist bethanechol. To our knowledge, BSM is the first visceral SM cell line that expresses the SM-B isoform and might serve as a useful model to study the transcriptional regulation of tissue-specific SMM isoforms in differentiation and pathological SM.

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159: Deletion of SM-B, the High Atpase Isoform of Myosin, Upregulates the PKC-Mediated Signal Transduction Pathway in the Urinary Bladder Smooth Muscle

The Journal of Urology ◽

10.1016/s0022-5347(18)32426-1 ◽

2006 ◽

Vol 175 (4S) ◽

pp. 51-51

Author(s):

Joseph A. Hypolite ◽

Shaohua Chang ◽

Edward Labelle ◽

Gopal J. Babu ◽

Muthu Periasamy ◽

...

Keyword(s):

Signal Transduction ◽

Smooth Muscle ◽

Urinary Bladder ◽

Signal Transduction Pathway ◽

Transduction Pathway ◽

Bladder Smooth Muscle ◽

Urinary Bladder Smooth Muscle

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Evidence that action potential generation is not the exclusive determinant to trigger spontaneous myogenic contraction of guinea-pig urinary bladder smooth muscle

Acta Physiologica Scandinavica ◽

10.1046/j.1365-201x.2002.01009.x ◽

2002 ◽

Vol 176 (1) ◽

pp. 57-63 ◽

Cited By ~ 4

Author(s):

T. Imai ◽

Y. Tanaka ◽

T. Okamoto ◽

Y. Yamamoto ◽

T. Horinouchi ◽

...

Keyword(s):

Smooth Muscle ◽

Urinary Bladder ◽

Guinea Pig ◽

Action Potential ◽

Action Potential Generation ◽

Potential Generation ◽

Bladder Smooth Muscle ◽

Urinary Bladder Smooth Muscle

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Stretch-induced Calcium Release in Smooth Muscle

The Journal of General Physiology ◽

10.1085/jgp.20028514 ◽

2002 ◽

Vol 119 (6) ◽

pp. 533-543 ◽

Cited By ~ 76

Author(s):

Guangju Ji ◽

Robert J. Barsotti ◽

Morris E. Feldman ◽

Michael I. Kotlikoff

Keyword(s):

Smooth Muscle ◽

Urinary Bladder ◽

Smooth Muscle Cells ◽

Calcium Release ◽

Muscle Cells ◽

Intraluminal Pressure ◽

Bladder Smooth Muscle ◽

Urinary Bladder Smooth Muscle ◽

Inward Currents ◽

Longitudinal Stretch

Smooth muscle cells undergo substantial increases in length, passively stretching during increases in intraluminal pressure in vessels and hollow organs. Active contractile responses to counteract increased transmural pressure were first described almost a century ago (Bayliss, 1902) and several mechanisms have been advanced to explain this phenomenon. We report here that elongation of smooth muscle cells results in ryanodine receptor–mediated Ca2+ release in individual myocytes. Mechanical elongation of isolated, single urinary bladder myocytes to ∼120% of slack length (ΔL = 20) evoked Ca2+ release from intracellular stores in the form of single Ca2+ sparks and propagated Ca2+ waves. Ca2+ release was not due to calcium-induced calcium release, as release was observed in Ca2+-free extracellular solution and when free Ca2+ ions in the cytosol were strongly buffered to prevent increases in [Ca2+]i. Stretch-induced calcium release (SICR) was not affected by inhibition of InsP3R-mediated Ca2+ release, but was completely blocked by ryanodine. Release occurred in the absence of previously reported stretch-activated currents; however, SICR evoked calcium-activated chloride currents in the form of transient inward currents, suggesting a regulatory mechanism for the generation of spontaneous currents in smooth muscle. SICR was also observed in individual myocytes during stretch of intact urinary bladder smooth muscle segments. Thus, longitudinal stretch of smooth muscle cells induces Ca2+ release through gating of RYR. SICR may be an important component of the physiological response to increases in luminal pressure in smooth muscle tissues.

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