Biomol Ther.  2018 Nov;26(6):546-552. 10.4062/biomolther.2018.053.

Effect of Sphingosine-1-Phosphate on Intracellular Free Ca2+ in Cat Esophageal Smooth Muscle Cells

• Lee DK
• Min YS
• Yoo SS
• Shim HS
• Park SY
• Sohn UD

• KMID: 2427507
• DOI: http://doi.org/10.4062/biomolther.2018.053

Abstract

A comprehensive collection of proteins senses local changes in intracellular Ca²âº concentrations ([Ca²âº](i) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular Ca²âº concentrations in cat esophageal smooth muscle cells. To measure [Ca²âº](i) levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in [Ca²âº](i) in the cells. Pretreatment with EGTA, an extracellular Ca²âº chelator, decreased the S1P-induced increase in [Ca²âº](i), and an L-type Ca²âº-channel blocker, nimodipine, decreased the effect of S1P. This indicates that Ca²âº influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an InsP₃ receptor blocker, the S1P-evoked increase in [Ca²âº](i) was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of G(i)-protein, suppressed the increase in [Ca²âº](i) evoked by S1P. These results suggest that the S1P-induced increase in [Ca²âº](i) in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of Ca²âº from the InsP₃-sensitive Ca²âº pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular Ca²âº via the L type Ca²âº channel, which was dependent on activation of the S1Pâ‚„ receptor coupled to PTX-sensitive G(i) protein, via phospholipase C-mediated Ca²âº release from the InsP₃-sensitive Ca²âº pool in cat esophageal smooth muscle cells.

Keyword

Sphingosine-1-phosphate; Calcium; Fura-2; Esophageal cells; 2-Aminoethoxydiphenyl borate; Nimodipine

MeSH Terms

Animals
Calcium
Cats*
Egtazic Acid
Fura-2
Methods
Microscopy, Fluorescence
Muscle Contraction
Muscle, Smooth*
Myocytes, Smooth Muscle*
Nimodipine
Pertussis Toxin
Phospholipases
Sarcoplasmic Reticulum
Thapsigargin
Type C Phospholipases
Calcium
Egtazic Acid
Fura-2
Nimodipine
Pertussis Toxin
Phospholipases
Thapsigargin
Type C Phospholipases