Roles of Ca2+ and protein kinase C in the excitatory response to serotonin in embryonic molluscan ciliary cells.
We examined the roles of Ca2+ and protein kinase C (PKC) in the cilio-excitatory response to serotonin in pedal ciliary cells from Helisoma trivolvis embryos. Serotonin (5-hydroxytryptamine; 5-HT; 100 micromol/L) induced an increase in ciliary beat frequency (CBF) was abolished by microinjected BAPTA (50 mmol/L), but was only partially inhibited by the phospholipase C inhibitor U-73122 (10 micromol/L). The diacylglycerol analogs 1-oleoyl-2-acetyl-sn-glycerol (100 micromol/L) and 1,2-dioctanoyl-sn-glycerol (100 micromol/L) caused increases in [Ca2+]i that were smaller than those induced by serotonin. In the absence of extracellular Ca2+, 1,2-dioctanoyl-sn-glycerol (100 micromol/L) failed to elicit an increase in both CBF and [Ca2+]i. In contrast, the serotonin-induced increase in CBF persisted in the absence of extracellular Ca2+, although the increase in [Ca2+]i was abolished. PKC inhibitors bisindolylmaleimide (10 and 100 nmol/L) and calphostin C (10 nmol/L) partially inhibited the serotonin-induced increase in CBF, but didn't affect the serotonin-induced change in [Ca2+]i. These findings suggest that an intracellular store-dependent increase in [Ca2+]i mediates the cilio-excitatory response to serotonin. Furthermore, although PKC is able to cause an increase in [Ca2+]i through calcium influx, it contributes to the cilio-excitatory response to 5-HT through a different mechanism.
Doran
Shandra A
SA
Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
Goldberg
Jeffrey I
JI
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D002923:Cilia / Q000187:drug effects*; D004075:Diglycerides / Q000494:pharmacology; D004625:Embryo, Nonmammalian / Q000166:cytology; D018846:Excitatory Amino Acids / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D007211:Indoles / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D012908:Snails / Q000196:embryology*
D004075:Diglycerides; D018846:Excitatory Amino Acids; D007211:Indoles; D008301:Maleimides; D009281:Naphthalenes; D047428:Protein Kinase Inhibitors; C044295:1,2-dioctanoylglycerol; D012701:Serotonin; D015759:Ionomycin; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; C058819:calphostin C; C088060:bisindolylmaleimide; D002118:Calcium