Membrane properties and the excitatory junction potentials in smooth muscle cells of cochlear spiral modiolar artery in guinea pigs

1999 ◽  
Vol 138 (1-2) ◽  
pp. 171-180 ◽  
Author(s):  
Zhi-Gen Jiang ◽  
Jianhua Qiu ◽  
Tianying Ren ◽  
Alfred L. Nuttall
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Guinea Pigs ◽  
Muscle Cells ◽  
Membrane Properties ◽  
Excitatory Junction Potentials

Membrane properties and innervation of smooth muscle cells in Hirschsprung's disease

1983 ◽  
Vol 244 (4) ◽  
pp. G406-G415 ◽  
Author(s):  
M. Kubota ◽  
Y. Ito ◽  
K. Ikeda
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Large Intestine ◽  
Hirschsprung's Disease ◽  
Hirschsprung’S Disease ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Membrane Properties ◽  
Aganglionic Segment ◽  
Excitatory Junction Potentials

Mechanical and membrane properties of smooth muscle cells and/or neuroeffector transmission in the aganglionic segment of the large intestine (Hirschsprung's disease) were compared with findings in the ganglionic segment. Tension-recording, microelectrode, and double sucrose gap methods were used. There was no difference in resting membrane potential of the longitudinal or circular muscle cell in these two segments, which were obtained at biopsy in Japanese children. In the ganglionic preparations, generations of regular prepotentials, with or without the spike, correlated well to the rhythmic contractions. However, in the aganglionic segment, irregular spike and contraction only were observed. In the circular or longitudinal muscle of the ganglionic segments, field stimulations evoked inhibitory junction potentials, excitatory junction potentials, or both and triggered initial relaxation and then a contraction of the tissue. In the aganglionic segment, however, field stimulation evoked only excitatory junction potentials followed by contraction. These results indicate that, in cases of Hirschsprung's disease, there may be a deficiency in the nonadrenergic inhibitory pathways. This is the first evidence for a lack of spasticity in muscle from the aganglionic segment of the large intestine obtained from children with Hirschsprung's disease.

Loss of responsiveness of circular smooth muscle cells from the guinea pig ileum is associated with changes in gap junction coupling

2012 ◽  
Vol 302 (12) ◽  
pp. G1434-G1444 ◽  
Author(s):  
Simona E. Carbone ◽  
David A. Wattchow ◽  
Nick J. Spencer ◽  
Simon J. H. Brookes
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Gap Junction ◽  
Input Resistance ◽  
Muscle Cells ◽  
Dye Coupling ◽  
Circular Smooth Muscle ◽  
Gap Junction Coupling ◽  
Excitatory Junction Potentials ◽  
Junction Coupling

Gap junction coupling and neuromuscular transmission to smooth muscle were studied in the first 4 h after preparations were set up in vitro. Intracellular recordings were made from smooth muscle cells of guinea pig ileum. Fast inhibitory junction potentials (IJPs) were small (1.3 ± 1.0 mV) in the first 30 min but increased significantly over the first 120 min to 15.8 ± 0.9 mV ( n = 12, P < 0.001). Comparable increases in slow IJPs and excitatory junction potentials were also observed. During the same period, resting membrane potential depolarized from −58.8 ± 1.4 to −47.2 ± 0.4 mV ( n = 12, P < 0.001). Input resistance, estimated by intracellular current injection, decreased in parallel ( P < 0.05), and dye coupling, measured by intracellular injection of carboxyfluorescein, increased ( P < 0.001). Input resistance was higher and dye coupling was less in longitudinal than circular smooth muscle cells. Gap junction blockers [carbenoxolone (100 μM), 18β-glycyrrhetinic acid (10 μM), and 2-aminoethoxydiphenyl borate (50 μM)] hyperpolarized coupled circular smooth muscle cells, reduced the amplitude of fast and slow IJPs and excitatory junction potentials, increased input resistance, and reduced dye coupling. Local application of ATP (10 mM) mimicked IJPs and showed comparable increases in amplitude over the first 120 min; carbenoxolone and 2-aminoethoxydiphenyl borate significantly reduced ATP-evoked hyperpolarizations in coupled cells. In contrast, synaptic transmission between myenteric neurons was not suppressed during the first 30 min. Gap junction coupling between circular smooth muscle cells in isolated preparations was initially disrupted but recovered over the next 120 min to a steady level. This was associated with potent effects on neuromuscular transmission and responses to exogenous ATP.

Changes of gap junctions in myometrium of guinea pig at parturition and abortion

1982 ◽  
Vol 60 (3) ◽  
pp. 335-341 ◽  
Author(s):  
R. E. Garfield ◽  
E. E. Daniel ◽  
M. Dukes ◽  
J. D. Fitzgerald
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Gap Junctions ◽  
Gap Junction ◽  
Electron Micrographs ◽  
Guinea Pigs ◽  
Muscle Cells ◽  
Similar Increase ◽  
Junction Area

Myometrial tissues from guinea pigs were quantitatively examined for gap junctions in electron micrographs. Small numbers of gap junctions were present between smooth muscle cells in myometria of pregnant guinea pigs at days 50 and 65 of gestation. The junctions increased in number and size at parturition on day 69 and decreased again to control levels 24 h after parturition. A similar increase in junctions occurred when abortion was induced by 16,16-dimethylprostaglandin E2 (PGE2) on day 65. There were no consistent or significant differences in numbers of gap junctions from myometrium taken over sites of placental attachment and from other sites. These results together with previous studies suggest that an increase in myometrial gap junction area is associated with and may be essential for parturition in guinea pigs, but the control of their development may differ from that in other mammals.

Membrane properties of smooth muscle cells in pulmonary hypertensive rats

1982 ◽  
Vol 242 (5) ◽  
pp. H907-H915 ◽  
Author(s):  
H. Suzuki ◽  
B. M. Twarog
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Main Pulmonary Artery ◽  
Fold Increase ◽  
Muscle Cells ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Chronic Pulmonary Hypertension

The membrane properties of smooth muscle cells in rat main pulmonary artery (MPA) and small pulmonary artery (SPA) were investigated during chronic normobaric hypoxia and after monocrotaline injection. As chronic pulmonary hypertension developed, pronounced differences between MPA and SPA were observed. These findings may shed light on mechanisms of smooth muscle hypertrophy. 1) The resting membrane potential of smooth muscle in MPA became less negative than the normal (depolarized), whereas the resting membrane potential of smooth muscle in SPA became more negative (hyperpolarized). 2) In MPA, both the length and time constants diminished. 3) In MPA, the maximum membrane depolarization produced by a 10-fold increase in extracellular [K+] decreased. 4) In SPA, the depolarization observed in K+-free solution was more rapid and greater in amplitude, and the transient hyperpolarization following restoration of K+-containing solution increased. 5) In SPA, initial and sustained depolarization evoked by Na+-deficient solutions were increased. 6) Depolarization in MPA was due to increased membrane permeability, perhaps to Cl-, whereas hyperpolarization in SPA could be attributed to increased activity of an electrogenic Na+-K+ pump.

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