1. Constitutive and permissive roles of nitric oxide activity in embryonic ciliary cells.
- Author
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Doran SA, Tran CH, Eskicioglu C, Stachniak T, Ahn KC, and Goldberg JI
- Subjects
- Aminoquinolines pharmacology, Animals, Cells, Cultured, Cilia drug effects, Cyclic GMP pharmacology, Guanylate Cyclase antagonists & inhibitors, Guanylate Cyclase metabolism, Nitric Oxide Donors pharmacology, Penicillamine pharmacology, Serotonin pharmacology, Snails drug effects, Snails metabolism, Cilia metabolism, Cyclic GMP analogs & derivatives, Nitric Oxide metabolism, Penicillamine analogs & derivatives, Snails cytology, Snails embryology
- Abstract
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.
- Published
- 2003
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