title: Inhibitory effects of cations on the Ca2+ response of water fibers in the frog tongue.
abstract: The effects of various cations on water fibers in the frog (Rana catesbeiana) tongue were investigated. The following results were obtained. 1. Water fibers responded well to Ca2+ and Sr2+. 2. SO2-(4) did not inhibit the Ca2+ response. Cl- at high concentrations had an inhibitory effect on the response to high Ca2+ stimulation. However, when the Ca2+ concentration was low, Cl- did not induce any inhibition. Therefore, low Ca2+ stimulation (0.1 mM CaCl2) was used to examine the inhibitory effect of cation. 3. MgCl2 and MgSO4 strongly inhibited the response to low Ca2+ stimulation. The inhibition by Mg salts was not caused by anion but by Mg2+. 4. The Ca2+ response was inhibited by various cations. The order of the inhibitory effects of cations was as follows: La3+ greater than Mn2+ = Mg2+ greater than or equal to Ni2+ greater than Co2+ greater than monovalent cations (Na+, K+, NH4+ and choline+). 5. The Sr2+ response, as well as the Ca2+ response, was inhibited by Na+ and Mg2+.
mesh_terms: D000818:Animals; D001001:Anura; D002118:Calcium / Q000037:antagonists & inhibitors*; D002122:Calcium Chloride / Q000494:pharmacology; D002413:Cations, Divalent; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D011892:Rana catesbeiana; D012996:Solutions; D013324:Strontium / Q000494:pharmacology; D014059:Tongue / Q000502:physiology*
chemical_list: D002413:Cations, Divalent; D012996:Solutions; D008274:Magnesium; D002122:Calcium Chloride; D002118:Calcium; D013324:Strontium