scholarly journals All-or-None Contraction and Sodium Channels in a Subset of Circular Muscle Fibers of Squid Mantle

1996 ◽  
Vol 191 (3) ◽  
pp. 337-340 ◽  
Author(s):  
W. F. Gilly ◽  
T. Preuss ◽  
M. B. McFarlane
Keyword(s):  
Sodium Channels ◽  
Muscle Fibers ◽  
Circular Muscle

Sounding Response of the Kokanee and Sockeye Salmon

1968 ◽  
Vol 25 (6) ◽  
pp. 1115-1131 ◽  
Author(s):  
H. H. Harvey ◽  
W. S. Hoar ◽  
C. R. Bothern
Keyword(s):  
Sockeye Salmon ◽  
Bladder Wall ◽  
Muscle Fibers ◽  
Circular Muscle ◽  
Adrenergic Blockade ◽  
Kokanee Salmon ◽  
Associated Gas ◽  
Treated Fish ◽  
Gas Loss ◽  
Adrenergic Blocking

When frightened, sockeye and kokanee salmon dive into deeper waters. This is termed the "sounding response."The sounding response in these fish is accompanied by the expulsion of gas from the swimbladder via the pneumatic duct. This gas loss is active and results from the contraction of the circular muscle fibers in the wall of the swimbladder.Gas loss on sounding is reduced or obviated after exposure to adrenergic blocking agents and enhanced in fish treated with sympathomimetics. Circular muscle fibers in intact and isolated strips of swimbladder contracted in response to sympathomimetics, but this response was prevented after adrenergic blockade. These results suggest the concentration of the swimbladder and associated gas expulsion is under adrenergic control.In untreated fish, an average pressure of 28.1 mm Hg was required to force gas out of the swimbladder through the pneumatic duct. In antropine-treated fish this duct-release pressure fell to an average of 0.2 mm Hg. This suggests constriction of the pneumatic duct is under cholinergic control.Histologically, the pneumatic duct was continuous with the oesophagus and extended as a convoluted duct to the anterior end of the swimbladder. Smooth muscle fibers surrounded the duct along its length and some striated fibers were present at the point where the duct joined the oesophagus. Occlusion of the pneumatic duct may be through the contraction of either of these types of fibers.The term "Gasspuckreflex" as originally used by Franz described the loss of gas from the swimbladder of physostomes in response to decompression. The authors suggest this term be reserved for this passive loss of gas, and not applied to fright-induced gas loss, resulting from active contraction of the bladder wall.

scholarly journals Electrophysiological Studies of the Antrum Muscle Fibers of the Guinea Pig Stomach

1970 ◽  
Vol 55 (1) ◽  
pp. 48-62 ◽  
Author(s):  
H. Kuriyama ◽  
T. Osa ◽  
H. Tasaki
Keyword(s):  
Slow Wave ◽  
Longitudinal Muscle ◽  
Muscle Fibers ◽  
Circular Muscle ◽  
Slow Waves ◽  
The Other ◽  
Spike Generation ◽  
High K ◽  
Electrophysiological Studies ◽  
Guinea Pig Stomach

The membrane potentials of single smooth muscle fibers of various regions of the stomach were measured, and do not differ from those measured in intestinal muscle. Spontaneous slow waves with superimposed spikes could be recorded from the longitudinal and circular muscle of the antrum. The development of tension was preceded by spikes but often tension appeared only when the slow waves were generated. Contracture in high K solution developed at a critical membrane potential of -42 mv. MnCl2 blocked the spike generation, then lowered the amplitude of the slow wave. On the other hand, withdrawal of Na+, or addition of atropine and tetrodotoxin inhibited the generation of most of the slow waves but a spike could still be elicited by electrical stimulation. Prostigmine enhanced and prolonged the slow wave; acetylcholine depolarized the membrane without change in the frequency of the slow waves. Chronaxie for the spike generation in the longitudinal muscle of the antrum was 30 msec and conduction velocity was 1.2 cm/sec. The time constant of the foot of the propagated spike was 28 msec. The space constants measured from the longitudinal and circular muscles of the antrum were 1.1 mm and 1.4 mm, respectively.

The maturation of cortisone-treated embryonic duodenum in vitro. I. The villus

Development ◽  
1965 ◽  
Vol 14 (2) ◽  
pp. 161-168
Author(s):  
Raymond L. Hayes
Keyword(s):  
Alkaline Phosphatase ◽  
Chick Embryo ◽  
Enzymatic Activity ◽  
Physiological Activity ◽  
Muscle Fibers ◽  
Circular Muscle ◽  
Luminal Surface ◽  
Embryonic Chick ◽  
Duodenal Epithelium

Mitotic expansion of the mucosa coupled with contraction of intrinsic longitudinal and circular muscle fibers produces previllous ridges on the luminal surface of the embryonic chick duodenum by the thirteenth day of incubation. Subsequently, remodelling by periodic indentation of the mucosal surface yields primitive villi which expand and elongate to form the tall, finger-like projections characterizing the absorptive surface of the mature duodenum (Hilton, 1902; Pap, 1933; Coulombre & Coulombre, 1958). Coincident with the morphogenesis of the villus is the acquisition of enzymatic activity in its epithelium. As early as the 14th day of incubation of the chick embryo, alkaline phosphatase is detectable in the epithelial free border of the duodenum (Hancox & Hyslop, 1954), although other investigators report later appearances for this enzyme (Moog, 1950; Hébert, 1950). The onset of this physiological activity in the duodenal epithelium may be accelerated by exposure to adrenocorticoids as originally postulated by Hébert (1950).

scholarly journals A novel third mesh-like myometrial layer connects the longitudinal and circular muscle fibers -A potential stratum to coordinate uterine contractions-

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kyosuke Kagami ◽  
Masanori Ono ◽  
Takashi Iizuka ◽  
Takeo Matsumoto ◽  
Takashi Hosono ◽  
...  
Keyword(s):  
Muscle Fibers ◽  
Circular Muscle ◽  
Uterine Contractions

Sodium current and membrane potential in EDL muscle fibers from normal and dystrophic (mdx) mice

1991 ◽  
Vol 261 (4) ◽  
pp. C718-C725 ◽  
Author(s):  
C. Mathes ◽  
F. Bezanilla ◽  
R. E. Weiss
Keyword(s):  
Membrane Potential ◽  
Sodium Channels ◽  
Single Channel ◽  
Muscle Fibers ◽  
Mdx Mice ◽  
Apparent Difference ◽  
Sodium Currents ◽  
Edl Muscle ◽  
Single Channel Currents ◽  
Channel Properties

The macroscopic and single-channel properties of sodium currents and membrane potential were studied in intact extensor digitorum longus (EDL) muscle fibers from mdx (C57BL/10ScSn-mdx) and normal (C57BL/10SnJ) mice. The voltage dependence of activation and inactivation were determined and the associated gating charges were calculated to determine if the lack of dystrophin associated with the mdx condition has any influence on sodium channels either directly or by effects on the membrane environment of the channel. Sodium currents were recorded from cell-attached patches on EDL muscle fibers isolated by collagenase treatment and manual dissection. Both macroscopic and single-channel currents were studied. We found no apparent difference in the sodium channel properties from the two types of muscle. In addition, microelectrode measurements in both mdx and normal muscle fibers indicated similar resting membrane potentials (Vm around -95 mV), which suggests that the normal behavior of sodium channels in the muscle sarcolemma is unaffected by the X-linked gene defect.

Blockade by cAMP of native sodium channels of adult rat skeletal muscle fibers

1998 ◽  
Vol 275 (6) ◽  
pp. C1465-C1472 ◽  
Author(s):  
Jean-François Desaphy ◽  
Annamaria De Luca ◽  
Diana Conte Camerino
Keyword(s):  
Skeletal Muscle ◽  
Sodium Channels ◽  
Single Channel ◽  
Muscle Fibers ◽  
Rat Skeletal Muscle ◽  
Patch Clamp Technique ◽  
Cyclic Monophosphate ◽  
Adult Rat ◽  
Skeletal Muscle Fibers ◽  
Steady State Inactivation

Although the skeletal muscle sodium channel is a good substrate for cAMP-dependent protein kinase (PKA), no functional consequence was observed for this channel expressed in heterologous systems. Therefore, we investigated the effect of 8-(4-chlorophenylthio)adenosine 3′,5′-cyclic monophosphate (CPT-cAMP), a membrane-permeable cAMP analog, on the native sodium channels of freshly dissociated rat skeletal muscle fibers by means of the cell-attached patch-clamp technique. Externally applied CPT-cAMP (0.5 mM) reduced peak ensemble average currents by ∼75% with no change in kinetics. Single-channel conductance and normalized activation curves were unchanged by CPT-cAMP. In contrast, steady-state inactivation curves showed a reduction of the maximal available current and a negative shift of the half-inactivation potential. Similar effects were observed with dibutyryl adenosine 3′,5′-cyclic monophosphate but not with cAMP, which does not easily permeate the cell membrane. Incubation of fibers for 1 h with 10 μM H-89, a PKA inhibitor, did not prevent the effect of CPT-cAMP. Finally, the β-adrenoreceptor agonist isoproterenol mimicked CPT-cAMP when applied at 0.5 mM but had no effect at 0.1 mM. These results indicate that cAMP inhibits native skeletal muscle sodium channels by acting within the fiber, independently of PKA activation.

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