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Interstitial cells and phasic activity in the isolated mouse bladder
Author(s) -
LAGOU MAGDALINI,
DRAKE MARCUS J.,
MARKERINKVAN ITTERSUM MARJANNE,
DE VENTE JAN,
GILLESPIE JAMES I.
Publication year - 2006
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1111/j.1464-410x.2006.06255.x
Subject(s) - acetylcholine , choline acetyltransferase , chemistry , smooth muscle tissue , interstitial cell , urinary bladder , immunohistochemistry , cholinergic , paraformaldehyde , detrusor muscle , endocrinology , medicine , anatomy , biology , smooth muscle , organic chemistry
OBJECTIVE To describe the distribution of interstitial cells (ICs, defined as cells which show an increase in cGMP in response to nitric oxide, NO) in the isolated mouse bladder, and changes in phasic contractile activity after exposure to a NO donor. MATERIALS AND METHODS The whole bladder was removed from 17 female mice, killed by cervical dislocation. For immunohistochemistry (six mice) the bladder was incubated in carboxygenated Krebs’ solution at 36 °C, containing 1 m m of the phosphodiesterase inhibitor isobutyl‐methyl‐xanthine. Individual pieces of tissue were exposed to 100 µ m of the NO donor diethylamine NONOate for 10 min; control tissues remained in Krebs’ solution. Tissues were then fixed in 4% paraformaldehyde and processed for cGMP immunohistochemistry. Bladder pressure was measured in bladders from 11 mice; the bladders were cannulated via the urethra and suspended in a heated chamber containing carboxygenated Tyrode solution at 33–35 °C and intravesical pressure recorded. All drugs were added to the solution bathing the abluminal surface. RESULTS NO induced an increase in cGMP in cells in the outer layers of the bladder wall, forming two distinct types based on their location; cells lying on the surface of the muscle bundles (surface muscle ICs) and cells within the muscle bundles (intramuscular ICs). Cholinergic nerve fibres were identified by the expression of vesicular acetylcholine transporter and neuronal NO synthase (nNOS). Choline acetyltransferase‐ and nNOS‐positive nerves also had high cGMP levels in response to 100 µ m diethylamine NONOate. In vitro exposure of an isolated whole unstimulated bladder to 100 µ m diethylamine NONOate had no effect on resting bladder pressure. When whole bladders were exposed to muscarinic stimulation (30–100 n m arecaidine) there was an initial large transient rise in pressure followed by complex phasic changes in pressure. Adding 100 µ m diethylamine NONOate abolished this phasic activity. Interestingly, the phasic activity was inhibited midway between the peak and trough of a phasic cycle. Such a pattern of inhibition might reflect the complexity of the phasic activity involving both excitatory and inhibitory components. CONCLUSIONS These data show the presence of NO/cGMP‐sensitive ICs in the outer muscle layers of the mouse bladder. Activating these cells alters the pattern of muscarinic‐induced phasic activity. We suggest that the role of the ICs in the outer muscle layers is to generate and modulate phasic activity. If so, then this is the first report of a functional role for ICs in the bladder.