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Spontaneous electrical and Ca 2+ signals in the mouse renal pelvis that drive pyeloureteric peristalsis
Author(s) -
Lang Richard J,
Hashitani Hikaru,
Tonta Mary A,
Bourke Justin L,
Parkington Helena C,
Suzuki Hikaru
Publication year - 2010
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2009.05226.x
Subject(s) - interstitial cell of cajal , population , peristalsis , depolarization , ryanodine receptor , nifedipine , chemistry , medicine , pacemaker potential , biophysics , endocrinology , biology , microbiology and biotechnology , anatomy , receptor , calcium , smooth muscle , environmental health
Summary 1. Peristalsis in the smooth muscle cell (SMC) wall of the pyeloureteric system is unique in physiology in that the primary pacemaker resides in a population of atypical SMCs situated near the border of the renal papilla. 2. Atypical SMCs display high‐frequency Ca 2+ transients upon the spontaneous release of Ca 2+ from inositol 1,4,5‐trisphosphate (IP 3 )‐dependent stores that trigger cation‐selective spontaneous transient depolarizations (STDs). In the presence of nifedipine, these Ca 2+ transients and STDs seldom propagate > 100 μm. Synchronization of STDs in neighbouring atypical SMCs into an electrical signal that can trigger action potential discharge and contraction in the typical SMC layer involves a coupled oscillator mechanism dependent on Ca 2+ entry through L‐type voltage‐operated Ca 2+ channels. 3. A population of spindle‐ or stellate‐shaped cells, immunopositive for the tyrosine receptor kinase kit, is sparsely distributed throughout the pyeloureteric system. In addition, Ca 2+ transients and action potentials of long duration occurring at low frequencies have been recorded in a population of fusiform cells, which we have termed interstitial cells of Cajal (ICC)‐like cells. 4. The electrical and Ca 2+ signals in ICC‐like cells are abolished upon blockade of Ca 2+ release from either IP 3 ‐ or ryanodine‐dependent Ca 2+ stores. However, the spontaneous Ca 2+ signals in atypical SMCs or ICC‐like cells are little affected in W/W −v transgenic mice, which have extensive lesions of their intestinal ICC networks. 5. In summary, we have developed a model of pyeloureteric pacemaking in which atypical SMCs are indeed the primary pacemakers, but the function of ICC‐like cells has yet to be determined.