Korean J Physiol Pharmacol.  2013 Dec;17(6):531-536. 10.4196/kjpp.2013.17.6.531.

Spontaneous Electrical Activity of Cultured Interstitial Cells of Cajal from Mouse Urinary Bladder

• Kim SO
• Jeong HS
• Jang S
• Wu MJ
• Park JK
• Jiao HY
• Jun JY
• Park JS

• KMID: 2285481
• DOI: http://doi.org/10.4196/kjpp.2013.17.6.531

Abstract

Interstitial cells of Cajal (ICCs) from the urinary bladder regulate detrusor smooth muscle activities. We cultured ICCs from the urinary bladder of mice and performed patch clamp and intracellular Ca2+ ([Ca2+]i) imaging to investigate whether cultured ICCs can be a valuable tool for cellular functional studies. The cultured ICCs displayed two types of spontaneous electrical activities which are similar to those recorded in intact bladder tissues. Spontaneous electrical activities of cultured ICCs were nifedipine-sensitive. Carbachol and ATP, both excitatory neurotransmitters in the urinary bladder, depolarized the membrane and increased the frequency of spike potentials. Carbachol increased [Ca2+]i oscillations and basal Ca2+ levels, which were blocked by atropine. These results suggest that cultured ICCs from the urinary bladder retain rhythmic phenotypes similar to the spontaneous electrical activities recorded from the intact urinary bladder. Therefore, we suggest that cultured ICCs from the urinary bladder may be useful for cellular and molecular studies of ICCs.

Keyword

Interstitial cells of Cajal; Spontaneous electrical activities; Urinary bladder

MeSH Terms

Action Potentials
Adenosine Triphosphate
Animals
Atropine
Carbachol
Interstitial Cells of Cajal*
Membranes
Mice*
Muscle, Smooth
Neurotransmitter Agents
Phenotype
Urinary Bladder*
Adenosine Triphosphate
Atropine
Carbachol
Neurotransmitter Agents

Figure

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  Fig. 1 Cultured ICCs from the mouse urinary bladder. The tunica muscularis of the urinary bladder was digested with collagenase, and the dispersed cells were cultured for 2 days. Confocal microscope image of Kit-immunopositive ICCs showed networks in culture.

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  Fig. 2 Spontaneous electrical activities in cultured ICCs from mouse urinary bladder. The cultured ICCs exhibited two types' spontaneous electrical activities. One is individual generation of spontaneous spike potentials (A). The other is bursting generation of spontaneous spike potentials (B). Dotted lines indicate resting level of membrane potentials.

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  Fig. 3 Effect of nifedipine on spontaneous electrical activities in cultured ICCs from mouse urinary bladder. In cultured ICCs generated spontaneous spike potentials. Nifedipine (10-6 M) abolished the spontaneous spike potentials in both individual (A) and bursting (B) types. Dotted lines indicate resting level of membrane potentials.

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  Fig. 4 Effects of carbachol spontaneous electrical activities in cultured ICCs from mouse urinary bladder. Carbachol (10-8 M) produced depolarization of the resting membrane with an increase of the frequency of spontaneous spike potentials in individual type (A). In the bursting type, carbachol produced depolarization of the resting membrane with a decrease of the frequency of spontaneous spike potentials (B). Atropine (10-6 M) blocked the carbachol-induced effects on spontaneous spike potentials in both individual (C) and bursting (D) types. Dotted lines indicate resting level of membrane potentials. CCh: carbachol.

• 

  Fig. 5 Effects of ATP spontaneous electrical activities in cultured ICCs from mouse urinary bladder. ATP (5×10-6 M) produced depolarization of the resting membrane with an increase of the frequency of spontaneous spike potentials in bursting type (A). Dotted lines indicate resting level of membrane potentials. The changed values of resting membrane potential and frequency by ATP are summarized in (B) and (C).

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  Fig. 6 The regulation of carbachol on spontaneous Ca2+ oscillation in cultured ICCs from the mouse urinary bladder. (A) Sequential fluorescence intensity images of Fluo-3 loaded cultured ICCs by carbachol (10-8 M). In the presence of carbachol, the [Ca2+]i oscillations were increased. (B) Sequential fluorescence intensity images of Fluo-3 loaded cultured ICCs by carbachol in the presence of atropine (10-6 M). Atropine blocked the carbachol-induced effects on [Ca2+]i oscillations. CCh, carbachol.

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