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- Title
Role of Ca2+ entry and Ca2+ stores in atypical smooth muscle cell autorhythmicity in the mouse renal pelvis.
- Authors
Lang, R. J.; Hashitani, H.; Tonta, M. A.; Suzuki, H.; Parkington, H. C.
- Abstract
Background and purpose:Electrically active atypical smooth muscle cells (ASMCs) within the renal pelvis have long been considered to act as pacemaker cells driving pelviureteric peristalsis. We have investigated the role of Ca2+ entry and uptake into and release from internal stores in the generation of Ca2+ transients and spontaneous transient depolarizations (STDs) in ASMCs.Experimental approach:The electrical activity and separately visualized changes in intracellular Ca2+ concentration in typical smooth muscle cells (TSMCs), ASMCs and interstitial cells of Cajal-like cells (ICC-LCs) were recorded using intracellular microelectrodes and a fluorescent Ca2+ indicator, fluo-4.Results:In 1 μM nifedipine, high frequency (10–30 min−1) Ca2+ transients and STDs were recorded in ASMCs, while ICC-LCs displayed low frequency (1–3 min−1) Ca2+ transients. All spontaneous electrical activity and Ca2+ transients were blocked upon removal of Ca2+ from the bathing solution, blockade of Ca2+ store uptake with cyclopiazonic acid (CPA) and with 2-aminoethoxy-diphenylborate (2-APB). STD amplitudes were reduced upon removal of the extracellular Na+ or blockade of IP3 dependent Ca2+ store release with neomycin or U73122. Blockade of ryanodine-sensitive Ca2+ release blocked ICC-LC Ca2+ transients but only reduced Ca2+ transient discharge in ASMCs. STDs in ASMCS were also little affected by DIDS, La3+, Gd3+ or by the replacement of extracellular Cl- with isethionate.Conclusions:ASMCs generated Ca2+ transients and cation-selective STDs via mechanisms involving Ca2+ release from IP3-dependent Ca2+ stores, STD stimulation of TSMCs was supported by Ca2+ entry through L type Ca2+ channels and Ca2+ release from ryanodine-sensitive stores.British Journal of Pharmacology (2007) 152, 1248–1259; doi:10.1038/sj.bjp.0707535; published online 29 October 2007
- Subjects
MUSCLE cells; MYOBLASTS; PELVIS; ANATOMY; GASTROINTESTINAL motility; MEDICAL sciences; SODIUM metabolism; CELL metabolism; CALCIUM metabolism; INOSITOL phosphates; RESEARCH; MUSCLE contraction; INDOLE compounds; BORON compounds; ANIMAL experimentation; RESEARCH methodology; EVALUATION research; MEDICAL cooperation; KIDNEY pelvis; ELECTROPHYSIOLOGY; COMPARATIVE studies; NIFEDIPINE; MICE; PHARMACODYNAMICS
- Publication
British Journal of Pharmacology, 2007, Vol 152, Issue 8, p1248
- ISSN
0007-1188
- Publication type
journal article
- DOI
10.1038/sj.bjp.0707535