Sarafotoxin-induced calcium mobilization in cultured dog tracheal smooth muscle cells.
Sarafotoxin b (S6b)-induced changes in intracellular Ca2+ concentration ([Ca2+]i) were monitored in cultured canine tracheal smooth muscle cells (TSMCs) by a fluorescent Ca2+ indicator fura-2. S6b elicited an initial transient peak followed by a sustained elevation of [Ca2+]i. BQ-123, an endothelin-A (ETA) receptor antagonist, had a high affinity to block the rise in [Ca2+]i response to S6b. In the absence of external Ca2+, only an initial transient peak of [Ca2+]i was seen, the sustained elevation of [Ca2+]i could then be evoked by addition of 1.8 mM Ca2+. Ca2+ influx was required for the changes of [Ca2+]i, since the Ca(2+)-channel blockers, diltiazem, verapamil, and Ni2+, decreased both the initial and sustained elevation of [Ca2+]i in response to S6b. TSMCs pretreated with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min attenuated Ca2+ mobilization induced by S6b, which was reversed by staurosporine, a protein kinase C (PKC) inhibitor. The change of [Ca2+]i induced by S6b was attenuated by cholera toxin pretreatment, but not by pertussis toxin. These data demonstrate that the initial detectable increase in [Ca2+]i stimulated by S6b is due to the activation of ETA receptors and subsequent release of Ca2+ from internal stores, whereas the contribution of external Ca2+ follows and partially involves a diltiazem- and verapamil-sensitive process. The inhibition of PMA on S6b-induced Ca2+ mobilization was inversely correlated with membraneous PKC activity.
Yang
C M
CM
Department of Pharmacology, Chang Gung College of Medicine and Technology, Tao-Yuan, Taiwan, Republic of China.
Ong
R
R
Hsieh
J T
JT
Yo
Y L
YL
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D003593:Cytoplasm / Q000201:enzymology; D004285:Dogs; D005260:Female; D008297:Male; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D009532:Nickel / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D017466:Receptors, Endothelin / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014132:Trachea; D014757:Viper Venoms / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010456:Peptides, Cyclic; D017466:Receptors, Endothelin; D014757:Viper Venoms; C057354:sarafotoxins s6; D009532:Nickel; D002772:Cholera Toxin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D002118:Calcium