Constitutive and permissive roles of nitric oxide activity in embryonic ciliary cells.
Embryos of Helisoma trivolvis exhibit cilia-driven rotation within the egg capsule during development. In this study we examined whether nitric oxide (NO) is a physiological regulator of ciliary beating in cultured ciliary cells. The NO donor S-nitroso-N-acetylpenicillamine (SNAP; 1-1,000 microM) produced a dose-dependent increase in ciliary beat frequency (CBF). In contrast, the nitric oxide synthase (NOS) inhibitor 7-nitroindazole (10 and 100 microM) inhibited the basal CBF and blocked the stimulatory effects of serotonin (100 microM). NO production in response to serotonin was investigated with 4,5-diaminofluorescein diacetate imaging. Although SNAP (100 microM) produced a rise in NO levels in all cells, only 22% of cells responded to serotonin with a moderate increase. The cGMP analog 8-bromo-cGMP (8-Br-cGMP; 0.2 and 2 mM) increased CBF, and the soluble guanylate cyclase inhibitor LY-83583 (10 microM) blocked the cilioexcitatory effects of SNAP and serotonin. These data suggest that NO has a constitutive cilioexcitatory effect in Helisoma embryos and that the stimulatory effects of serotonin and NO work through a cGMP pathway. It appears that in Helisoma cilia, NO activity is necessary, but not sufficient, to fully mediate the cilioexcitatory action of serotonin.
Doran
Shandra A
SA
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
Tran
Cam Ha
CH
Eskicioglu
Cagla
C
Stachniak
Tev
T
Ahn
Kee-Chan
KC
Goldberg
Jeffrey I
JI
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002923:Cilia / Q000187:drug effects / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D012908:Snails / Q000166:cytology* / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism
D000634:Aminoquinolines; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D012701:Serotonin; C041715:6-anilino-5,8-quinolinedione; D006162:Guanylate Cyclase; D010396:Penicillamine; D006152:Cyclic GMP