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Ryanodine receptors in human bladder smooth muscle
Author(s) -
Chambers Pauline,
Neal David E.,
Gillespie James I.
Publication year - 1999
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1111/j.1469-445x.1999.tb00070.x
Subject(s) - ryanodine receptor , receptor , smooth muscle , biology , medicine , endocrinology , anatomy , chemistry , microbiology and biotechnology
SUMMARY The role of intracellular Ca 2+ release in the activation of human bladder smooth muscle is controversial. We have measured the expression of mRNA encoding for the ryanodine receptor (RyR) isoforms (RyR1, RyR2 and RyR3) in isolated human detrusor smooth muscle. mRNA for RyR2 was detected in all samples but no mRNA for RyR1 or RyR3 could be found. Human bladder smooth muscle cells in culture are unresponsive to caffeine, suggesting the absence of a functional RyR system. However, mRNA encoding for RyR2 was detected in these cells. Using saponin‐permeabilized cells, a Ruthenium Red‐sensitive Ca 2+ ‐dependent 45 Ca 2+ release could be demonstrated from the sarcoplasmic reticulum (SR). These data confirm the functional presence of Ca 2+ ‐induced Ca 2+ release (CICR) in cells and suggest that the properties of the RyR2 isoform in human detrusor may change when the cells are maintained in culture. The implications of these observations to detrusor smooth muscle function are discussed.