Effect of Gap Junction Blocker β-Glycyrrhetinic Acid on Taste Disk Cells in Frog
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A gap junction blocker, 18β-glycyrrhetinic acid (β-GA), increased the membrane resistance of Ia, Ib and II/III cells of frog taste disk by 50, 160, and 300 MΩ, respectively, by blocking the gap junction channels and hemichannels. The amplitudes of gustatory depolarizing potentials in the disk cells for 4 basic taste stimuli were reduced to 40–60% after intravenous injection of β-GA at 1.0 mg/kg. β-GA of 1.0 mg/kg did not affect the resting potentials and the reversal potentials for tastant-induced depolarizing potentials in any taste disk cells. The percentage of cells responding to each of 4 basic taste stimuli and varying numbers of 4 taste qualities did not differ between control and β-GA-treated taste disk cells. This implies that gustatory depolarizing response profiles for 4 basic taste stimuli were very similar in control and β-GA-treated taste disk cells. It is concluded that β-GA at 1.0 mg/kg reduced the amplitude of gustatory depolarizing potentials in taste disk cells by strongly blocking depolarizing currents flowing through the gap junction channels and hemichannels, but probably weakly affected the gustatory transduction mechanisms for 4 taste stimuli.
KeywordsFrog taste disk cell Depolarizing response profile Gap junction blocker Gap junction hemichannel Membrane resistance increase
This work was supported by Japan Society for the Promotion of Science (17570064).
- Ganong WF (2005) Review of medical physiology, 22nd edn. McGraw-Hill, New YorkGoogle Scholar
- Jaeger CB, Hillman DE (1976) Morphology of gustatory organs. In: Linás R, Precht W (eds) Frog neurobiology. Springer, Berlin, pp 587–606Google Scholar
- Miyamoto T, Okada Y, Sato T (1991) Voltage-gated membrane current of isolated bullfrog taste cells. Zool Sci 8:835–845Google Scholar
- Murray RG (1973) The ultrastructure of taste bud. In: Friedmann I (ed) The ultrastructure of sensory organs. North-Holland Publishing, Amsterdam, pp 1–39Google Scholar
- Rodriguez-Sinovas A, Cabestrero A, López D, Torre I, Morente M, Abellán A, Miró E, Ruiz-Meana M, Garcia-Dorado D (2007) The modulatory effects of connexin 43 on cell death/survival beyond cell coupling. Prog Biophys Mol Biol 94:219–232. doi: 10.1016/j.pbiomolbio.2007.03.003 PubMedCrossRefGoogle Scholar
- Sato T, Miyamoto T, Okada Y (1987) Latency of gustatory neural impulses initiated in frog tongue. Brain Res 424:333–342Google Scholar
- Thorson TB (1964) The partitioning of body water in Amphibia. Physiol Zool 37:395–399Google Scholar