scholarly journals SARCOPLASMIC RETICULUM AND EXCITATION-CONTRACTION COUPLING IN MAMMALIAN SMOOTH MUSCLES

1972 ◽  
Vol 52 (3) ◽  
pp. 690-718 ◽  
Author(s):  
Carrick E. Devine ◽  
Avril V. Somlyo ◽  
Andrew P. Somlyo
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Pulmonary Artery ◽  
Mesenteric Artery ◽  
Electromechanical Coupling ◽  
Surface Membrane ◽  
Main Pulmonary Artery ◽  
Smooth Muscles ◽  
Taenia Coli ◽  
Virtual Absence ◽  
Mesenteric Vein

The sarcoplasmic reticulum (SR) was studied in the smooth muscles of rabbit main pulmonary artery, mesenteric vein, aorta, mesenteric artery, taenia coli, guinea pig mesenteric artery, and human uterus, and correlated with contractions of the smooth muscles in Ca-free media. SR volumes were determined in main pulmonary artery (5.1%), aorta (5%), portal-anterior mesenteric vein (2.2%), taenia coli (2%), and mesenteric artery (1.8%): because of tangentially sectioned membranes these estimates are subject to a correction factor of up to +50% of the values measured. Smooth muscles that contained a relatively large volume of SR maintained significant contractile responses to drugs in the virtual absence of extracellular calcium at room temperatures, while smooth muscles that had less SR did not. The unequal maximal contractions of main pulmonary artery elicited by different drugs were also observed in Ca-free, high potassium-depolarizing solution, indicating that they were secondary to some mechanism independent of changes in membrane potential or calcium influx. Longitudinal tubules of SR run between and are fenestrated about groups of surface vesicles separated from each other by intervening dense bodies. Extracellular markers (ferritin and lanthanum) entered the surface vesicles, but not the SR. The peripheral SR formed couplings with the surface membrane: the two membranes were separated by gaps of approximately 10 nm traversed by electron-opaque connections suggestive of a periodicity of approximately 20–25 nm. These couplings are considered to be the probable sites of electromechanical coupling in twitch smooth muscles. Close contacts between the SR and the surface vesicles may have a similar function, or represent sites of calcium extrusion. The presence of both thick and thin myofilaments and of rough SR in smooth muscles supports the dual, contractile and morphogenetic, function of smooth muscle.

Sarcoplasmic reticulum and mitochondria as cation accumulation sites in smooth muscle

1973 ◽  
Vol 265 (867) ◽  
pp. 17-23 ◽  
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Divalent Cation ◽  
Electromechanical Coupling ◽  
Surface Membrane ◽  
Smooth Muscles ◽  
Relative Volume ◽  
Electron Dense Material ◽  
Tubular System ◽  
Central Elements

A tubular system of sarcoplasmic reticulum that is not penetrated by extracellular markers is described in vertebrate smooth muscles. The sarcoplasmic reticulum forms fenestrations around the surface vesicles and also forms close appositions (an approximately 10 to 12 nm gap traversed by periodic electron dense material) with the non-specialized surface membrane. The morphological couplings are considered to be the most probable sites of electromechanical coupling of the action potential to the twitch contraction. The relative volume of the sarcoplasmic reticulum varies in functionally different (tonic and phasic) smooth muscles, and correlates with the ability of the different smooth muscles to contract in the absence of extracellular calcium. Electron opaque deposits of strontium are accumulated by peripheral and central elements of the sarcoplasmic reticulum. The accumulation of strontium and barium by mitochondria raises the possibility that, in addition to the sarcoplasmic reticulum, mitochondria may play a role in the regulation of intracellular divalent cation levels in vertebrate smooth muscle.

scholarly journals SARCOPLASMIC RETICULUM AND THE TEMPERATURE-DEPENDENT CONTRACTION OF SMOOTH MUSCLE IN CALCIUM-FREE SOLUTIONS

1971 ◽  
Vol 51 (3) ◽  
pp. 722-741 ◽  
Author(s):  
Andrew P. Somlyo ◽  
Carrick E. Devine ◽  
Avril V. Somlyo ◽  
Stanley R. North
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Extracellular Space ◽  
Room Temperature ◽  
Electromechanical Coupling ◽  
Contractile Response ◽  
Surface Membrane ◽  
Smooth Muscles ◽  
Smooth Muscle Contraction ◽  
Free Cell

The contractile response of turtle oviduct smooth muscle to acetylcholine after 30 min of incubation of muscles in Ca-free, 4 mM ethylene (bis) oxyethylenenitrilotetraacetic acid (EGTA) solutions at room temperature was greater than the contractile response after 30 min of incubation in the Ca-free medium at 37°C. Incubation in Ca-free solution at 37°C before stimulation with acetylcholine in Ca-free solutions at room temperature also reduced the contractile response, suggesting that activator calcium was lost from the fibers at a faster rate at higher temperatures. Electron micrographs of turtle oviduct smooth muscle revealed a sarcoplasmic reticulum (SR) occupying approximately 4% of the nucleus- and mitochondria-free cell volume. Incubation of oviduct smooth muscle with ferritin confirmed that the predominantly longitudinally oriented structures described as the SR did not communicate with the extracellular space. The SR formed fenestrations about the surface vesicles, and formed close contacts (couplings) with the surface membrane and surface vesicles in oviduct and vena caval smooth muscle; it is suggested that these are sites of electromechanical coupling. Calculation of the calcium requirements for smooth muscle contraction suggest that the amount of SR observed in the oviduct smooth muscle could supply the activator calcium for the contractions observed in Ca-free solutions. Incubation of oviduct smooth muscle in hypertonic solutions increased the electron opacity of the fibers. A new feature of some of the surface vesicles observed in oviduct, vena caval, and aortic smooth muscle was the presence of approximately 10 nm striations running approximately parallel to the openings of the vesicles to the extracellular space. Thick, thin, and intermediate filaments were observed in turtle oviduct smooth muscle, although the number of thick filaments seen in the present study appeared less than that previously found in mammalian smooth muscles.

Coupling mechanisms in airway smooth muscle

1990 ◽  
Vol 258 (4) ◽  
pp. L119-L133 ◽  
Author(s):  
R. F. Coburn ◽  
C. B. Baron
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Airway Smooth Muscle ◽  
Electromechanical Coupling ◽  
Cell Function ◽  
Surface Membrane ◽  
Smooth Muscles ◽  
Membrane Receptors ◽  
Airway Smooth Muscle Cells ◽  
Coupling Mechanisms

This review documents available information about coupling mechanisms involved in airway smooth muscle force development and maintenance and relaxation of force. Basic concepts, obtained from experiments performed on many different mammalian cell types, are in place regarding coupling between surface membrane receptors and cell function; these concepts are considered as a framework for understanding coupling between receptors and contractile proteins in smooth muscles and in airway smooth muscles. We have divided various components of coupling mechanisms into those dependent on changes in the surface membrane potential (electromechanical coupling) and those independent of the surface membrane potential (pharmacomechanical coupling). We have, to some degree, emphasized modulation of coupling mechanisms by intrasurface membrane microprocessing or by second messengers. A challenge for the future is to obtain a better understanding of how coupling mechanisms are altered or modulated during different phases of contractions evoked by a single agonist and under conditions of multiple agonist exposure to airway smooth muscle cells.

scholarly journals Inactivation of Gi proteins by pertussis toxin diminishes the effectiveness of adrenergic stimuli in conduit arteries from spontaneously hypertensive rats

2008 ◽  
pp. 299-302
Author(s):  
A Zemančíková ◽  
J Török ◽  
J Zicha ◽  
J Kuneš
Keyword(s):  
Pulmonary Artery ◽  
Thoracic Aorta ◽  
Pertussis Toxin ◽  
Mesenteric Artery ◽  
Spontaneously Hypertensive Rats ◽  
Main Pulmonary Artery ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
The Right ◽  
Gi Proteins

Treatment with pertussis toxin (PTX) which eliminates the activity of Gi proteins effectively reduces blood pressure (BP) and vascular resistance in spontaneously hypertensive rats (SHR). In this study we have compared the functional characteristics of isolated arteries from SHR with and without PTX-treatment (10 μg/kg i.v., 48 h before the experiment). Rings of thoracic aorta, superior mesenteric artery and main pulmonary artery were studied under isometric conditions to measure the reactivity of these vessels to receptor agonists and to transmural electrical stimuli. We have found that the treatment of SHR with PTX had no effect on endothelium-dependent relaxation of thoracic aorta induced by acetylcholine. In PTX-treated SHR, the maximum contraction of mesenteric artery to exogenous noradrenaline was reduced and the dose-response curve to cumulative concentration of noradrenaline was shifted to the right. Similarly, a reduction in the magnitude of neurogenic contractions elicited by electrical stimulation of perivascular nerves was observed in the mesenteric artery from PTX-treated SHR. PTX treatment of SHR also abolished the potentiating effect of angiotensin II on neurogenic contractions of the main pulmonary artery. These results indicate that PTX treatment markedly diminishes the effectiveness of adrenergic stimuli in vasculature of SHR. This could importantly affect BP regulation in genetic hypertension.

Effects of diltiazem on smooth muscles and neuromuscular junction in the mesenteric artery

1982 ◽  
Vol 242 (3) ◽  
pp. H325-H336 ◽  
Author(s):  
H. Suzuki ◽  
T. Itoh ◽  
H. Kuriyama
Keyword(s):  
Mesenteric Artery ◽  
Channel Blocker ◽  
Surface Membrane ◽  
Smooth Muscles ◽  
Membrane Resistance ◽  
Membrane Properties ◽  
Ca Channel ◽  
Mechanical Responses ◽  
Ca Antagonist ◽  
Excitatory Junction Potentials

Effects of diltiazem on membrane properties, neuromuscular transmissions, and mechanical responses were investigated in intact and skinned muscles of the guinea pig mesenteric artery. Diltiazem (greater than 10(-6) M) depolarized the membrane, increased the membrane resistance, and suppressed the spike evoked by either electrical depolarization or summation of excitatory junction potentials (EJPs). This drug also suppressed the facilitation process of amplitudes of EJPs produced by repetitive perivascular nerve stimulations. These suppressions of EJPs were not caused by a reduced number of active nerves contributing to the generation of EJP but but rather to a reduction in the release of chemical transmitters. Norepinephrine (NE)-induced and K-induced contractions were suppressed by diltiazem noncompetitively, but the contraction evoked in Na-deficient solution was not suppressed, i.e., diltiazem is not a nonselective inhibitor of the Ca influx. In the saponin-treated skinned muscles diltiazem did not suppress the release from or the accumulation into the Ca store site, nor did it suppress activation of the Ca receptor in contractile proteins. These results indicate that diltiazem acts on the surface membrane and nerve terminal as a Ca antagonist or Ca-channel blocker.

scholarly journals ELECTROMECHANICAL COUPLING IN TUBULAR MUSCLE FIBERS

1972 ◽  
Vol 52 (3) ◽  
pp. 626-638 ◽  
Author(s):  
Arieh Gilai ◽  
I. Parnas
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cell Membrane ◽  
Electromechanical Coupling ◽  
Surface Membrane ◽  
Hexagonal Array ◽  
Thin Filaments ◽  
Transverse Tubular System ◽  
The Core ◽  
Tubular System ◽  
Terminal Cisternae

The tubular fibers of the claw-closer muscle of the scorpion have a central core containing nuclei and mitochondria. The myofibrils have the shape of thin lamellae (1 µ) extending radially from the core to the surface membrane (20 µ). The thick myofilaments are organized in a hexagonal array with orbits of 10–13 thin myofilaments. The ratio of thick-to-thin filaments is 1:5. Transverse tubular system (TS) openings are located between lamellated myofibrils. In each sarcomere two TS's are found, one on each side of the H band. The TS is composed of a transverse tubule and tubular pockets (TP). The TP's form diadic contact with the terminal cisternae of the sarcoplasmic reticulum. The TS can be traced from the cell membrane down to the cell core. The surface area of the TS was calculated to be six times that of the outer surface membrane.

scholarly journals Pulmonary atresia with a ventricular septal defect and left pulmonary artery discontinuity: a case report 

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Hyun-Hwa Cha ◽  
Hae Min Kim ◽  
Won Joon Seong
Keyword(s):  
Pulmonary Artery ◽  
Subclavian Artery ◽  
Septal Defect ◽  
Left Subclavian Artery ◽  
Ductus Arteriosus ◽  
Main Pulmonary Artery ◽  
Pulmonary Arteries ◽  
Pulmonary Atresia ◽  
Left Pulmonary Artery ◽  
Right Pulmonary Artery

Abstract Background Unilateral pulmonary artery discontinuity is a rare malformation that is associated with other intracardiac abnormalities. Cases accompanied by other cardiac abnormalities are often missed on prenatal echocardiography. The prenatal diagnosis of isolated unilateral pulmonary artery discontinuity can also be delayed. However, undiagnosed this malformation would have an effect on further prognosis. We report our case of a prenatal diagnosis of pulmonary atresia with ventricular septal defect and left pulmonary artery discontinuity. Case presentation A 33-year-old Asian woman visited our institution at 24 weeks of gestation because of suspected fetal congenital heart disease. Fetal echocardiography revealed a small atretic main pulmonary artery giving rise to the right pulmonary artery without bifurcation and the left pulmonary artery arising from the ductus arteriosus originating from the left subclavian artery. The neonate was delivered by cesarean section at 376/7 weeks of gestation. Postnatal echocardiography and multidetector computed tomography showed a right aortic arch, with the small right pulmonary artery originating from the atretic main pulmonary artery and the left pulmonary artery originating from the left subclavian artery. Patency of the ductus arteriosus from the left subclavian artery was maintained with prostaglandin E1. Right ventricular outflow tract reconstruction and pulmonary angioplasty with Gore-Tex graft patch was performed 25th day after birth. Unfortunately, the neonate died because of right heart failure 8 days postoperation. Conclusion There is a possibility that both pulmonary arteries do not arise from the same great artery (main pulmonary artery or common arterial trunk). Therefore, clinicians should check the origin of both pulmonary arteries.

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