The influence of temperature on the thick filaments of vertebrate smooth muscle

1973 ◽  
Vol 265 (867) ◽  
pp. 197-202 ◽  
Keyword(s):  
Smooth Muscle ◽  
Guinea Pigs ◽  
Taenia Coli ◽  
Thin Filaments ◽  
Influence Of Temperature ◽  
Thick Filaments ◽  
Influence Of Temperature On ◽  
10 Nm Filaments ◽  
Ion Analysis

When fixation of taenia coli from adult guinea-pigs is initiated at 37 °C only thin filaments and 10 nm filaments are preserved. At 37 °G (i.e. as in vivo ) thick filaments are very labile; to preserve them during fixation much thinner muscles must be used such as taenia coli from very young animals. The thick filaments from taenia coli of adult guinea-pigs can however be stabilized by pre-cooling the living muscles before fixation at 37 °C. An ion analysis of these muscles in vivo, and during fixation at 37 and 4 °C, showed that there is a K and Na ion exchange in the tissue both on cooling and during fixation; the exchange is most rapid on fixation particularly when it takes place at 37 °C. The Mg 2+ content appears to be unaffected by these conditions, but the Ca 2+ content rises both on cooling and during fixation (when the uptake is unexpectedly large). The selective destruction of the cell membrane is greatest when fixation is carried out at 37 °C. It is suggested that pre-cooling may alter thick filaments.

scholarly journals THICK FILAMENTS IN VASCULAR SMOOTH MUSCLE

1971 ◽  
Vol 49 (3) ◽  
pp. 636-649 ◽  
Author(s):  
Carrick E. Devine ◽  
Andrew P. Somlyo
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Actin Filaments ◽  
Vas Deferens ◽  
Average Diameter ◽  
Physiological Salt Solution ◽  
Taenia Coli ◽  
Striated Muscles ◽  
Thin Filaments ◽  
Thick Filaments

Two sets of myofilaments were demonstrated after incubation of strips of rabbit portal-anterior mesenteric vein under moderate stretch in a physiological salt solution. Thick filaments had a mean diameter of 18 nm and reached a maximum length of 1.4 µm with a mean length of 0.61 µm. In transverse sections, 2.5–5 nm particles were resolved as subunits of the thick filaments. Thin filaments had an average diameter of 8.4 nm and generally conformed to the structure believed to represent actin filaments in smooth and striated muscles. In the areas of maximum concentration there were 160–328 thick filaments/µm2 and the lowest ratio of thin to thick filaments was 12:1. Thick filaments were present in approximately equal numbers in vascular smooth muscle relaxed by theophylline, in Ca++-free solution, or contracted by norepinephrine. The same preparatory procedures used with vascular smooth muscle also enabled us to visualize thick filaments in guinea pig and rabbit taenia coli and vas deferens.

scholarly journals Dense bodies and actin polarity in vertebrate smooth muscle.

1982 ◽  
Vol 95 (2) ◽  
pp. 403-413 ◽  
Author(s):  
M Bond ◽  
A V Somlyo
Keyword(s):  
Smooth Muscle ◽  
Vas Deferens ◽  
Dense Body ◽  
Thin Filaments ◽  
Dense Bodies ◽  
Thick Filaments ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
10 Nm Filaments ◽  
Rabbit Vas Deferens

The arrangement of cytoplasmic dense bodies in vertebrate smooth muscle and their relationship to the thin filaments was studied in cells from rabbit vas deferens and portal vein which were made hyperpermeable (skinned) with saponin and incubated with myosin subfragment 1 (S-1). The dense bodies were obliquely oriented, elongated structures sometimes appearing as chains up to 1.5 microns in length; they were often continuous across the cell for 200 to 300 nm and were interconnected by an oblique network of 10-nm filaments. The arrowheads, formed by S-1 decoration of actins, which inserted into both the sides and ends of dense bodies, always pointed away from the dense body, similar to the polarity of the thin filaments at the Z-bands of skeletal muscle. These results show that the cytoplasmic dense bodies function as anchoring sites for the thin filaments and indicate that the thin filaments, thick filaments, and dense bodies constitute a contractile unit.

scholarly journals THE ORGANIZATION OF CONTRACTILE FILAMENTS IN A MAMMALIAN SMOOTH MUSCLE

1970 ◽  
Vol 47 (1) ◽  
pp. 183-196 ◽  
Author(s):  
Robert V. Rice ◽  
Joan A. Moses ◽  
G. M. McManus ◽  
Arlene C. Brady ◽  
Lorraine M. Blasik
Keyword(s):  
Smooth Muscle ◽  
Thin Filament ◽  
Nearest Neighbor ◽  
Striated Muscle ◽  
Taenia Coli ◽  
X Ray Diffraction ◽  
Thin Filaments ◽  
Ordered Arrays ◽  
Thick Filaments ◽  
Filament Spacing

Ordered arrays of thin filaments (65 A diameter) along with other apparently random arrangements of thin and thick filaments (100–200 A diameter) are observed in contracted guinea pig taenia coli rapidly fixed in glutaraldehyde. The thin-filament arrays vary from a few to more than 100 filaments in each array. The arrays are scattered among isolated thin and thick filaments. Some arrays are regular such as hexagonal; other arrays tend to be circular. However, few examples of rosettes with regular arrangements of thin filaments surrounding thick filaments are seen. Optical transforms of electron micrographs of thin-filament arrays give a nearest-neighbor spacing of the thin filaments in agreement with the "actin" filament spacing from x-ray diffraction experiments. Many thick filaments are closely associated with thin-filament arrays. Some thick filaments are hollow circles, although triangular shapes are also found. Thin-filament arrays and thick filaments extend into the cell for distances of at least a micron. Partially relaxed taenia coli shows thin-filament arrays but few thick filaments. The suggestion that thick filaments aggregate prior to contraction and disaggregate during relaxation is promoted by these observations. The results suggest that a sliding filament mechanism operates in smooth muscle as well as in striated muscle.

scholarly journals ULTRASTRUCTURAL STUDIES ON THE CONTRACTILE MECHANISM OF SMOOTH MUSCLE

1969 ◽  
Vol 42 (3) ◽  
pp. 683-694 ◽  
Author(s):  
Robert E. Kelly ◽  
Robert V. Rice
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Striated Muscle ◽  
Smooth Muscle Contraction ◽  
Nuclear Chromatin ◽  
Taenia Coli ◽  
Thin Filaments ◽  
Ultrastructural Studies ◽  
Thick Filaments ◽  
Morphological Differences

Fresh taenia coli and chicken gizzard smooth muscle were studied in the contracted and relaxed states. Thick and thin filaments were observed in certain (but not all) cells fixed in contraction. Relaxed smooth muscle contained only thin filaments. Several other morphological differences were observed between contracted and relaxed smooth muscle. The nuclear chromatin is clumped in contraction and evenly dispersed in the relaxed state. The sarcolemma is more highly vesiculated in contraction than in relaxation. In contraction, the sarcoplasm also appears more electron opaque. Over-all morphological differences between cells fixed in isometric and in unloaded contraction were also noticeable. The results suggest a sliding filament mechanism of smooth muscle contraction; however, in smooth muscle, unlike striated muscle, the thick filaments appear to be in a highly labile condition in the contractile process. The relation between contraction and a possible change in pH is also discussed.

scholarly journals LOCALIZATION OF MYOSIN FILAMENTS IN SMOOTH MUSCLE

1968 ◽  
Vol 37 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Robert E. Kelly ◽  
Robert V. Rice
Keyword(s):  
Smooth Muscle ◽  
Cross Section ◽  
Striated Muscle ◽  
Thick Filament ◽  
Longitudinal Axis ◽  
Thin Filaments ◽  
Chicken Gizzard ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Muscle Myosin

Thick myosin filaments, in addition to actin filaments, were found in sections of glycerinated chicken gizzard smooth muscle when fixed at a pH below 6.6. The thick filaments were often grouped into bundles and run in the longitudinal axis of the smooth muscle cell. Each thick filament was surrounded by a number of thin filaments, giving the filament arrangement a rosette appearance in cross-section. The exact ratio of thick filaments to thin filaments could not be determined since most arrays were not so regular as those commonly found in striated muscle. Some rosettes had seven or eight thin filaments surrounding a single thick filament. Homogenates of smooth muscle of chicken gizzard also showed both thick and thin filaments when the isolation was carried out at a pH below 6.6, but only thin filaments were found at pH 7.4. No Z or M lines were observed in chicken gizzard muscle containing both thick and thin filaments. The lack of these organizing structures may allow smooth muscle myosin to disaggregate readily at pH 7.4.

Influence of Temperature on Performance in Guinea Pigs

1957 ◽  
Vol 190 (3) ◽  
pp. 457-458 ◽  
Author(s):  
Charles G. Wilber
Keyword(s):  
Low Temperatures ◽  
Guinea Pigs ◽  
Peak Performance ◽  
Albino Rats ◽  
Small Animals ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Endocrine Factors ◽  
The Difference ◽  
Large Animals

Guinea pigs were forced to swim to total exhaustion in water at various temperatures. Small animals (400 gm) showed peak performance at about 40°C, large ones (1000 gm) at about 35°C. Large animals swam longer at low temperatures but shorter at high temperatures than did small ones. At 35°C all guinea pigs swam for an average of about 150 minutes. In general this species shows much less capacity for swimming than do albino rats. The difference may be related to diet or to endocrine factors.

scholarly journals The GABAA agonist muscimol attenuates induced airway constriction in guinea pigs in vivo

2009 ◽  
Vol 106 (4) ◽  
pp. 1257-1263 ◽  
Author(s):  
Neil R. Gleason ◽  
George Gallos ◽  
Yi Zhang ◽  
Charles W. Emala
Keyword(s):  
Smooth Muscle ◽  
Cell Membrane ◽  
Airway Smooth Muscle ◽  
Guinea Pigs ◽  
Neural Control ◽  
Chronic Obstructive ◽  
Airway Smooth Muscle Cells ◽  
Membrane Hyperpolarization ◽  
Airway Constriction

GABAA channels are ubiquitously expressed on neuronal cells and act via an inward chloride current to hyperpolarize the cell membrane of mature neurons. Expression and function of GABAA channels on airway smooth muscle cells has been demonstrated in vitro. Airway smooth muscle cell membrane hyperpolarization contributes to relaxation. We hypothesized that muscimol, a selective GABAA agonist, could act on endogenous GABAA channels expressed on airway smooth muscle to attenuate induced increases in airway pressures in anesthetized guinea pigs in vivo. In an effort to localize muscimol's effect to GABAA channels expressed on airway smooth muscle, we pretreated guinea pigs with a selective GABAA antagonist (gabazine) or eliminated lung neural control from central parasympathetic, sympathetic, and nonadrenergic, noncholinergic (NANC) nerves before muscimol treatment. Pretreatment with intravenous muscimol alone attenuated intravenous histamine-, intravenous acetylcholine-, or vagal nerve-stimulated increases in peak pulmonary inflation pressure. Pretreatment with the GABAA antagonist gabazine blocked muscimol's effect. After the elimination of neural input to airway tone by central parasympathetic nerves, peripheral sympathetic nerves, and NANC nerves, intravenous muscimol retained its ability to block intravenous acetylcholine-induced increases in peak pulmonary inflation pressures. These findings demonstrate that the GABAA agonist muscimol acting specifically via GABAA channel activation attenuates airway constriction independently of neural contributions. These findings suggest that therapeutics directed at the airway smooth muscle GABAA channel may be a novel therapy for airway constriction following airway irritation and possibly more broadly in diseases such as asthma and chronic obstructive pulmonary disease.

scholarly journals Cofilin loss in Drosophila contributes to myopathy through defective sarcomerogenesis and aggregate formation during muscle growth

2019 ◽  
Author(s):  
Mridula Balakrishnan ◽  
Shannon F. Yu ◽  
Samantha M. Chin ◽  
David B. Soffar ◽  
Stefanie E. Windner ◽  
...  
Keyword(s):  
Point Mutation ◽  
Muscle Function ◽  
Muscle Growth ◽  
Nemaline Myopathy ◽  
Aggregate Formation ◽  
Thin Filaments ◽  
Sarcomeric Protein ◽  
Thick Filaments

SUMMARYSarcomeres, the fundamental contractile units of muscles, are conserved structures composed of actin thin filaments and myosin thick filaments. How sarcomeres are formed and maintained is not well understood. Here, we show that knockdown of Drosophila Cofilin (DmCFL), an actin depolymerizing factor, leads to the progressive disruption of sarcomere structure and muscle function in vivo. Loss of DmCFL also results in the formation of sarcomeric protein aggregates and impairs sarcomere addition during growth. Strikingly, activation of the proteasome delayed muscle deterioration in our model. Further, we investigate how a point mutation in CFL2 that causes nemaline myopathy (NM) in humans, affects CFL function and leads to the muscle phenotypes observed in vivo. Our data provide significant insights to the role of CFLs during sarcomere formation as well as mechanistic implications for disease progression in NM patients.

Increased in vitro responses of tracheal smooth muscle from hyperresponsive guinea pigs

1990 ◽  
Vol 68 (4) ◽  
pp. 1316-1320 ◽  
Author(s):  
K. Ishida ◽  
P. D. Pare ◽  
R. J. Thomson ◽  
R. R. Schellenberg
Keyword(s):  
Smooth Muscle ◽  
Guinea Pigs ◽  
Airway Hyperresponsiveness ◽  
Contractile Activity ◽  
Tracheobronchial Tree ◽  
Force Generation ◽  
Tracheal Smooth Muscle ◽  
Antigen Challenge

Repeated aerosol antigen challenge of previously sensitized guinea pigs induces airway hyperresponsiveness to inhaled acetylcholine. To determine the mechanism producing these airway changes and assuming that changes in the trachealis muscle reflect changes in muscle of the entire tracheobronchial tree, we examined the in vitro smooth muscle mechanics and morphometric parameters of tracheae from guinea pigs demonstrating hyperresponsiveness in vivo vs. tracheae from control guinea pigs. No differences between these groups were found in luminal volume at zero transmural pressure, passive pressure-volume characteristics, or area of airway wall. Smooth muscle areas were slightly less in tracheae from hyperresponsive guinea pigs. Tracheae from hyperresponsive guinea pigs had both significantly increased isovolumetric force generation and isobaric shortening compared with tracheae from controls when evaluated over the range of transmural pressures from -40 to 40 cmH2O. We conclude that the in vivo airway hyperresponsiveness induced with repeated antigen challenge is associated with both increased force generation and shortening of tracheal smooth muscle without increased muscle mass, suggesting enhanced contractile activity.

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