Multiple calcium signaling pathways in Mardin-Darby canine kidney cells
Sakano, S.; Takemura, H.; Ohshika, H.
Research Communications in Molecular Pathology and Pharmacology 86(2): 175-182
1994
ISSN/ISBN: 1078-0297 PMID: 7533628 Document Number: 425059
Effects of various receptor agonists on cytoplasmic Ca-2+ concentration ((Ca-2+)-i) were examined in fura-2-loaded Mardin-Darby canine kidney (MDCK) monolayer cells. Carbachol (100 mu-M) increased (Ca-2+)-i which slightly declined to a sustained increase in (Ca-2+)-i. On the other hand, (Ca-2+)-i elevated by 100 nM bradykinin (BK) declined to a resting level of (Ca-2+)-i even in the presence of BK. After washout of BK, the subsequent addition of a higher concentration of BK (1 mu-M) caused a smaller increase in (Ca-2+)-i than that induced by 100 nM BK. Isoproterenol (100 mu-M) did not increase (Ca-2+)-i by itself but caused an transient increase in (Ca-2+)-i In the presence of 1 mM isobutylmethylxanthine (IBMX) Prostaglandin E-1 (1 mu-M) resulted in a slight increase in (Ca-2+)-i which was potentiatedin the presence of 1 mM IBMX. The microsomal Ca-2+-ATPase inhibitor thapsigargin (100 nM) caused a sustained increase in (Ca-2+)-i. These results suggest that MDCK cells have multiple Ca-2+ signaling pathways which may regulate epithelial cell functions. Therefore, the high potency of ST-630 in stimulating bone resorption in organ culture may be associated with a difference between ST-630 and 1,25(OH)-2D-3 in the mode of metabolism in the cultured bones.