Regional variation in myosin isoforms and phosphorylation at the resting tone in urinary bladder smooth muscle

2001 ◽  
Vol 280 (2) ◽  
pp. C254-C264 ◽  
Author(s):  
Joseph A. Hypolite ◽  
Michael E. DiSanto ◽  
Yongmu Zheng ◽  
Shaohua Chang ◽  
Alan J. Wein ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Smooth Muscles ◽  
Urinary Continence ◽  
Myosin Isoforms ◽  
Bladder Smooth Muscle ◽  
Rt Pcr ◽  
Total Rna ◽  
Bladder Dome ◽  
Significant Difference

Urinary bladder filling and emptying requires coordinated control of bladder body and urethral smooth muscles. Bladder dome, midbladder, base, and urethra showed significant differences in the percentage of 20-kDa myosin light chain (LC20) phosphorylation (35.45 ± 4.6, 24.7 ± 2.2, 13.6± 2.1, and 12.8 ± 2.7%, respectively) in resting muscle. Agonist-mediated force was associated with a rise in LC20 phosphorylation, but the extent of phosphorylation at all levels of force was less for urethral than for bladder body smooth muscle. RT-PCR and quantitative competitive RT-PCR analyses of total RNA from bladder body and urethral smooth muscles revealed only a slight difference in myosin heavy chain mRNA copy number per total RNA, whereas mRNA copy numbers for NH2-terminal isoforms SM-B (inserted) and SM-A (noninserted) in these muscles showed a significant difference (2.28 × 108 vs. 1.68 × 108 for SM-B and 0.12 × 108 vs. 0.42 × 108 for SM-A, respectively), which was also evident at the protein level. The ratio of COOH-terminal isoforms SM2:SM1 in the urethra was moderately but significantly lower than that in other regions of the bladder body. A high degree of LC20phosphorylation and SM-B in the bladder body may help to facilitate fast cross-bridge cycling and force generation required for rapid emptying, whereas a lower level of LC20 phosphorylation and the presence of a higher amount of SM-A in urethral smooth muscle may help to maintain the high basal tone of urethra, required for urinary continence.

Expression of myosin isoforms in smooth muscle cells in the corpus cavernosum penis

1998 ◽  
Vol 275 (4) ◽  
pp. C976-C987 ◽  
Author(s):  
Michael E. DiSanto ◽  
Ze Wang ◽  
Chandrakala Menon ◽  
Yongmu Zheng ◽  
Thomas Chacko ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Amino Acid ◽  
Smooth Muscles ◽  
Corpus Cavernosum ◽  
Muscle Cells ◽  
Myosin Isoforms ◽  
Bladder Smooth Muscle ◽  
Rt Pcr ◽  
Two Dimensional Gel Electrophoresis ◽  
Resting Tone

Corpus cavernosum smooth muscle (CCSM) in the penis is unique in that it exhibits a high resting tone and, on stimulation, the muscle cells relax, allowing cavernous spaces to fill with blood, which results in an erection (tumescence). During detumescence, the muscle cells contract and return to the state of high resting tone. This study was undertaken to determine whether CCSM with these unique properties contains myosin isoforms typical of aorta or bladder smooth muscles, muscles that exhibit tonic and phasic characteristics, respectively. RT-PCR revealed that normal CCSM contains an SM2/SM1 mRNA ratio of 1.2:1 (similar to the rabbit aorta). Approximately 31% of the myosin heavy chain transcripts possess a 21-nt insert (predominant in bladder smooth muscle but not expressed in aorta) that encodes the seven-amino acid insert near the NH2-terminal ATP binding region in the head portion of the myosin molecule found in SMB, with the remaining mRNA being noninserted (SMA). Quantitative competitive RT-PCR revealed that the CCSM possesses ∼4.5-fold less SMB than the bladder smooth muscle. Western blot analysis using an antibody specific for the seven-amino acid insert reveals that both SM1 and SM2 in the CCSM contain the seven-amino acid insert. Furthermore, SMB containing the seven-amino acid insert was localized in the CCSM by immunofluorescence microscopy using this highly specific antibody. The analysis of the expression of LC17isoforms a and b in the CCSM revealed that it is similar to that of bladder smooth muscle. Thus the CCSM possesses an overall myosin isoform composition intermediate between aorta and bladder smooth muscles, which generally express tonic- and phasiclike characteristics, respectively. Two-dimensional gel electrophoresis showed a relatively low level (∼10%) of Ca2+-dependent light-chain (LC20) phosphorylation at the basal tone, which reaches ∼23% in response to maximal stimulation. The presence of noninserted and inserted myosin isoforms with low and high levels of actin-activated ATPase activities, respectively, in the CCSM may contribute to the ability of the CCSM to remain in a state of high resting tone and to relax rapidly for normal penile function.

Plasticity of KIR channels in human smooth muscle cells from internal thoracic artery

2003 ◽  
Vol 284 (6) ◽  
pp. H2325-H2334 ◽  
Author(s):  
Tom Karkanis ◽  
Shaohua Li ◽  
J. Geoffrey Pickering ◽  
Stephen M. Sims
Keyword(s):  
Smooth Muscle ◽  
Current Density ◽  
Internal Thoracic Artery ◽  
Smooth Muscles ◽  
Vascular Smooth Muscles ◽  
Rt Pcr ◽  
Regulation Of Proliferation ◽  
Negative Membrane Potential ◽  
Inwardly Rectifying ◽  
Contractile Cells

Inwardly rectifying K+ (KIR) currents are present in some, but not all, vascular smooth muscles. We used patch-clamp methods to examine plasticity of this current by comparing contractile and proliferative phenotypes of a clonal human vascular smooth muscle cell line. Hyperpolarization of cells under voltage clamp elicited a large inward current that was selective for K+ and blocked by Ba2+. Current density was greater in proliferative compared with contractile cells (−4.5 ± 0.9 and −1.4 ± 0.3 pA/pF, respectively; P < 0.001). RT-PCR of mRNA from proliferative cells identified transcripts for Kir2.1 and Kir2.2 but not Kir2.3 potassium channels. Western blot analysis demonstrated greater expression of Kir2.1 protein in proliferative cells, consistent with the higher current density. Proliferative cells displayed a more negative membrane potential than contractile cells (−71 ± 2 and −35 ± 4 mV, respectively; P < 0.001). Ba2+ depolarized all cells, whereas small increases in extracellular K+ concentration elicited hyperpolarization only in contractile cells. Ba2+ inhibited [3H]thymidine incorporation, indicating a possible role for KIR channels in the regulation of proliferation. The phenotype-dependent plasticity of KIR channels may have relevance to vascular remodeling.

scholarly journals Stretch-induced Calcium Release in Smooth Muscle

2002 ◽  
Vol 119 (6) ◽  
pp. 533-543 ◽  
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.

In vitro and in vivo relaxation of urinary bladder smooth muscle by the selective myosin II inhibitor, blebbistatin

2011 ◽  
Vol 107 (2) ◽  
pp. 310-317 ◽  
Author(s):  
Xinhua Zhang ◽  
Dwaraka Srinivasa R. Kuppam ◽  
Arnold Melman ◽  
Michael E. DiSanto
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Myosin Ii ◽  
Bladder Smooth Muscle ◽  
Urinary Bladder Smooth Muscle

Smooth muscles from spastic coronary artery segments show hypercontractility to histamine

1990 ◽  
Vol 259 (1) ◽  
pp. H9-H13 ◽  
Author(s):  
S. Satoh ◽  
H. Tomoike ◽  
W. Mitsuoka ◽  
S. Egashira ◽  
H. Tagawa ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Coronary Arteries ◽  
Muscle Fibers ◽  
Coronary Spasm ◽  
Smooth Muscles ◽  
Bolus Administration ◽  
Luminal Diameter ◽  
Endothelial Denudation ◽  
Significant Difference

An animal model of coronary spasm was produced in Gottingen miniature pigs by a selective endothelial denudation of the coronary artery. Five months after the denudation, intracoronary bolus administration of 10 micrograms/kg histamine reduced the luminal diameter angiographically by 57 +/- 16 and 17 +/- 10% (P less than 0.01) in the previously denuded and contralateral control coronary arteries. Muscle fibers of 0.08–0.1 mm wide were prepared from circumferential bundles of the medial smooth muscle in the spastic and nonspastic coronary arteries. Upward shifts of either dose-tonic contraction relationships in Ca2(+)-containing solution or dose-monophasic contraction relationships in Ca2(+)-free solution were noted in muscle fibers taken from the spastic site compared with those from the nonspastic site with no difference between the mean effective dose values. After skinning the muscle fibers with saponin, there was no significant difference in the Ca2+ concentration-tension relationships between the two fibers. These findings suggest that an increased number of histaminergic receptors and/or augmentation of signal transduction, but not Ca2+ sensitivity of the contractile proteins in the medial smooth muscle cells, cause histamine-induced coronary hypercontraction.

Altered expression of thin filament-associated proteins in hypertrophied urinary bladder smooth muscle

2005 ◽  
Vol 25 (1) ◽  
pp. 78-88 ◽  
Author(s):  
Anita S. Mannikarottu ◽  
Michael E. DiSanto ◽  
Stephen A. Zderic ◽  
Alan J. Wein ◽  
Samuel Chacko
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Thin Filament ◽  
Bladder Smooth Muscle ◽  
Altered Expression ◽  
Associated Proteins ◽  
Urinary Bladder Smooth Muscle

scholarly journals Expression and functional role of Rho-kinase in rat urinary bladder smooth muscle

2003 ◽  
Vol 138 (5) ◽  
pp. 757-766 ◽  
Author(s):  
Alexandra Wibberley ◽  
Zunxuan Chen ◽  
Erding Hu ◽  
J Paul Hieble ◽  
Timothy D Westfall
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Functional Role ◽  
Rho Kinase ◽  
Bladder Smooth Muscle ◽  
Rat Urinary Bladder ◽  
Urinary Bladder Smooth Muscle
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