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- Title
Photolysis of caged cyclic AMP in the ciliary cytoplasm of the newt olfactory receptor cell.
- Authors
Takeuchi, Hiroko; Kurahashi, Takashi
- Abstract
The effects of cyclic nucleotide monophosphate (cNMP) in the ciliary cytoplasm of the olfactory receptor cell were examined by using photolysis of caged cNMP loaded from the whole-cell patch clamp pipette. Illumination of the cilia induced an inward current at −50 mV. The current amplitude was voltage dependent and the polarity was reversed at +10 mV. The amplitude of the light-induced current was dependent on both light intensity and duration. The intensity-response relation was fitted well by the Hill equation with a coefficient ( nH) of 4.99 ± 2.66 (mean ± s.d., n= 19) and the duration-response relation with a coefficient of 4.03 ± 1.43 ( n= 17). The activation time course of adenylyl cyclase was estimated by comparing the light-induced response with the odorant-induced response. Adenylyl cyclase was activated approximately 260 ms later from the onset of the odorant-stimulation. The light-induced current developed very sharply. This could be explained by the sequential openings of cAMP-gated and Ca2+-activated Cl − channels. At +100 mV, where Ca2+ influx is expected to be very small, the current rising phase became less steep. When the cells were stimulated by long steps of either odour or light, the odorant-induced current showed stronger decay than the light-induced response. This observation suggests that the molecular system regulating desensitization is situated upstream of cAMP production.
- Publication
Journal of Physiology, 2002, Vol 541, Issue 3, p825
- ISSN
0022-3751
- Publication type
Article
- DOI
10.1113/jphysiol.2002.016600