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Calcium and olfactory transduction
B D Winegar1, E R Rosick, R Schafer
1Department of Biological Sciences, University of North Texas, Denton 76203-5218.
Abstract:
1. Inorganic cations, organic calcium antagonists, and calmodulin antagonists were applied to olfactory epithelia of frogs (Rana pipiens) while recording electroolfactogram (EOG) responses. 2. Inorganic cations inhibited EOGs in a rank order, reflecting their calcium channel blocking potency: La3+ greater than Zn2+ greater than Cd2+ greater than Al3+ greater than Ca2+ greater than Sr2+ greater than Co2+ greater than Ba2+ greater than Mg2+. Barium ion significantly enhanced EOGs immediately following application. 3. Diltiazem and verapamil produced dose-dependent EOG inhibition. 4. Calmodulin antagonists inhibited EOGs without correlation to their anti-calmodulin potency.
Insights
Inorganic cations and calcium channel blockers inhibit frog olfactory responses (EOGs), with varying potencies. Barium ions uniquely enhanced EOGs, suggesting complex olfactory signaling mechanisms.
Area of Science:
- Olfactory neurobiology
- Sensory physiology
- Ion channel pharmacology
Background:
- The olfactory system detects environmental chemicals, crucial for survival.
- Ion channels play a vital role in olfactory signal transduction.
- Calcium ions are implicated in olfactory receptor function.
Purpose of the Study:
- To investigate the role of inorganic cations and specific antagonists in modulating olfactory epithelium responses.
- To determine the rank order of calcium channel blocking potency for various inorganic cations.
- To assess the effects of organic calcium antagonists and calmodulin antagonists on electroolfactogram (EOG) responses.
Main Methods:
- Recording electroolfactogram (EOG) responses from frog olfactory epithelia.
- Application of inorganic cations (e.g., La3+, Zn2+, Ca2+, Ba2+, Mg2+).
- Administration of organic calcium antagonists (diltiazem, verapamil) and calmodulin antagonists.
Main Results:
- Inorganic cations inhibited EOGs, with potency correlating to calcium channel blocking ability (La3+ > Zn2+ > ... > Mg2+).
- Barium ions (Ba2+) transiently enhanced EOGs.
- Diltiazem and verapamil caused dose-dependent EOG inhibition.
- Calmodulin antagonists inhibited EOGs, but without correlation to their anti-calmodulin potency.
Conclusions:
- Inorganic cations and organic calcium antagonists significantly impact olfactory signal processing in frogs.
- The observed rank order suggests calcium channels are key targets for these modulators in the olfactory epithelium.
- Barium's enhancing effect warrants further investigation into its specific mechanism.