The action of the ionophore ionomycin in guinea-pig intestinal smooth muscle

1983 ◽  
Vol 61 (5) ◽  
pp. 535-538 ◽  
Author(s):  
G. T. Bolger ◽  
C. R. Triggle ◽  
D. J. Triggle
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Intestinal Smooth Muscle ◽  
Contraction Coupling ◽  
Longitudinal Smooth Muscle ◽  
A 23187 ◽  
Low Concentrations ◽  
Tissue Responses ◽  
Muscle Responses

The ionophore ionomycin produced concentration-dependent (5 × 10−9 to 5 × 10−6 M) contractions in guinea-pig ileal longitudinal smooth muscle. Responses were dependent on extracellular Ca2+, consistent with the known role of this Ca2+ source in supporting excitation–contraction coupling to a variety of stimulants in this tissue. Responses were insensitive to atropine (10−6 M) but were dependent upon extracellular Na+ and were completely blocked by low concentrations of the Ca2+-channel antagonists nicardipine. YC-93 (5 × 10−7 M), and D-600 (5 × 10−6 M). The behaviour of ionomycin is very similar to that shown by A 23187 in this tissue. Ionomycin, like A 23187, can apparently activate D-600 sensitive Ca2+ channels in the guinea-pig intestinal smooth muscle rather than simply translocating Ca2+EXT.

The mechanism of action of ionophore A 23187 on guinea pig intestinal smooth muscle

1979 ◽  
Vol 57 (4) ◽  
pp. 348-358 ◽  
Author(s):  
Lois B. Rosenberger ◽  
D. J. Triggle
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Mechanism Of Action ◽  
Calcium Antagonists ◽  
Intestinal Smooth Muscle ◽  
Phase System ◽  
Muscarinic Agonist ◽  
Two Phase ◽  
Longitudinal Smooth Muscle ◽  
A 23187

The cation ionophore A 23187 behaves similarly to the potent muscarinic agonist, cis-2-methyl-4-dimethylaminomethyl-1,3-dioxolane methiodide (CD) in guinea pig ileal longitudinal smooth muscle generating contractile responses that are gradedly sensitive to the concentrations of Ca2+ext and Na+ext. A 23187 and CD responses are insensitive to tetrodotoxin and A 23187 responses are insensitive to atropine. The responses to CD, A 23187, and veratridine are all similarly sensitive to the calcium antagonists D 600 and BAY-1040. D 600 failed to antagonize the ability of A 23187 to transport Ca2+ in a toluene-butanol: water two-phase system. It is suggested that in guinea pig ileal smooth muscle A 23187 does not translocate Ca2+ext exclusively but serves also to activate Ca2+ channels perhaps by an initial depolarizing Na+ entry.

The Action of the Ionophores, X-537A and A-23187, on Smooth Muscle

1975 ◽  
Vol 53 (6) ◽  
pp. 1108-1114 ◽  
Author(s):  
V. C. Swamy ◽  
M. Ticku ◽  
C. R. Triggle ◽  
D. J. Triggle
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Vas Deferens ◽  
Intestinal Smooth Muscle ◽  
Contractile Effect ◽  
Longitudinal Smooth Muscle ◽  
A 23187 ◽  
Reserpine Treatment

The cation ionophore X-537A in the concentration range of 10−6 to 3 × 10−5 M produced contractions in the rat and guinea-pig vas deferens. No contractile effect was produced in either of the vasa deferentia preparations by the ionophore A-23187 in the concentration range of 10−7 to 5 × 10−5 M. In contrast, X-537A had no contractile effect on the guinea-pig ileal longitudinal smooth muscle while A-23187 produced a dose and [Ca2+] dependent contraction.The contractile effect of X-537A in the vasa deferentia preparations is abolished by phenoxybenzamine or prior reserpine treatment and is therefore attributed to the release of norepinephrine. The effect of A-23187 in the intestinal smooth muscle is attributed to a direct Ca2+ transporting action since its contractile effect is unaffected by histamine, acetylcholine, or 5-hydroxytryptamine antagonists.

Role of the epithelium in airway smooth muscle responses to relaxant agonists

1991 ◽  
Vol 71 (4) ◽  
pp. 1434-1440 ◽  
Author(s):  
J. N. Yang ◽  
W. Mitzner ◽  
C. Hirshman
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Diffusion Barrier ◽  
Tracheal Wall ◽  
Maximal Effect ◽  
Direct Measurements ◽  
Dose Dependent ◽  
Muscle Responses

We studied the role of the guinea pig tracheal epithelium in modulating tracheal smooth muscle responses to the relaxant agonists albuterol, sodium nitroprusside, and theophylline. We used an in vitro preparation that allowed separation of the fluids bathing the luminal (internal) and serosal (external) surfaces of the trachea, and bronchodilators were administered to either surface of carbachol-contracted tracheae. All three drugs produced dose-dependent relaxation. However, albuterol and nitroprusside were less potent (concentration that produced half-maximal effect increased by 100- and 32-fold, respectively) when given to the epithelial side with the epithelium intact compared with the epithelium denuded or compared with serosal administration with the epithelium intact. These differences were not observed for theophylline, where smooth muscle responses were independent of either the side of stimulation or of the presence or absence of the epithelium. Direct measurements of the diffusion of theophylline across the tracheal wall in the presence or absence of epithelium showed that after 5 h of incubation with a fixed luminal concentration of theophylline, only 1.7% had diffused across the tracheal wall with the epithelium intact. This increased to only approximately 3.3% when the epithelium was denuded. These results suggest that the epithelial is a relatively weak barrier for lipophilic agents but has a major role as a diffusion barrier to hydrophilic substances.

scholarly journals INFLUENCE OF ANTIBIOTICS ON THE MECHANICAL RESPONSES OF GUINEA-PIG ILEUM TO ACETYLCHOLINE AND HISTAMINE

1998 ◽  
Vol 13 (3) ◽  
pp. 145-147
Author(s):  
Andy Petroianu ◽  
JÚLIO WEINBERG
Keyword(s):  
Smooth Muscle ◽  
Side Effects ◽  
Guinea Pig ◽  
Guinea Pig Ileum ◽  
Mechanical Responses ◽  
Longitudinal Smooth Muscle ◽  
Before And After ◽  
Muscle Responses

The side effects of antibiotics have been extensively described during the last decades, however, their role on digestive motility must be better investigated. Following a line of research, the influence of penicillin, chloranfenicol tetracycline and gentamicine on longitudinal smooth muscle responses to acetylcholine and histamine were studied on guinea-pig ileum. There were no differences between the responses before and after the addition of each antibiotic. Further investigations must be performed in order to find a possible influence of antibiotics on digestive motility.

ERG K+ channels modulate the electrical and contractile activities of gallbladder smooth muscle

2003 ◽  
Vol 284 (3) ◽  
pp. G392-G398 ◽  
Author(s):  
Edward Parr ◽  
Maria J. Pozo ◽  
Burton Horowitz ◽  
Mark T. Nelson ◽  
Gary M. Mawe
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Guinea Pig ◽  
Action Potential ◽  
Resting Membrane Potential ◽  
Plateau Phase ◽  
Related Gene ◽  
K Channels ◽  
Contraction Coupling

The current study was undertaken to test the existence and possible role of ether-a-go-go-related gene 1 (ERG1) protein K+ channels in gallbladder smooth muscle (GBSM). Transcripts encoding ERG1 were detected in human, mouse, and guinea pig GBSM, and ERG1 immunoreactivity was observed in GBSM cells. In intracellular voltage recordings, addition of E-4031 (100 nM–1 μM) or cisapride (100 nM–2 μM) caused concentration-dependent excitation of guinea pig GBSM that was not affected by 500 nM TTX + 5 μM atropine, and E-4031 also depolarized the resting membrane potential. In muscle strip studies, E-4031 either induced phasic contractions or significantly increased the amplitude of phasic contractions in spontaneously active tissues ( P = 0.001). E-4031 also potentiated bethanechol-induced contractions. In conclusion, ERG1 channels are expressed in the GBSM, where they play a role in excitation-contraction coupling probably by contributing to repolarization of the plateau phase of the action potential and to the resting membrane potential.

Role of stat6 in hypercontractility of murine small intestinal smooth muscle induced by nematode infection

2001 ◽  
Vol 120 (5) ◽  
pp. A534-A534
Author(s):  
A ZHAO ◽  
D MULLOY ◽  
J URBANJR ◽  
W GAUSE ◽  
T SHEADONOHUE
Keyword(s):  
Smooth Muscle ◽  
Nematode Infection ◽  
Intestinal Smooth Muscle ◽  
Small Intestinal
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