We investigated the effects of opioid agonists on the capsaicin-evoked release of glutamate from nociceptive primary afferent fibers of the rat (6-8 weeks) using a fluorometric on-line continuous monitoring system for glutamate. In the presence of 0.3 microM tetrodotoxin, the application of 3 microM capsaicin to spinal dorsal horn slices produced an evoked… (More)
Removal of NA+ and/or Ca2+ from a normal interstitial fluid results in a remarkable decrease of receptor potential amplitudes in a taste cell for salt stimuli. This suggests that the salt-induced receptor potential is strongly related to an increase in the permeability of the taste cell membrane to Na+ and Ca2+.
The aim of this study is to elucidate whether the excitatory amino acid glutamate is released from capsaicin-sensitive primary afferent fibers, and to compare the releasing effect of capsaicin on glutamate with that on substance P. The release of glutamate was measured using a fluorometric on-line continuous monitoring system, in which the immobilized… (More)
1. After the frog tongue was adapted for 10 sec to various salts and sugars, the initial phasic component of gustatory neural responses to almost all of quinine hydrochloride (Q-HCl), quinine sulfate (Q-H2SO4). Brucine, caffeine and picric acid was suppressed. 2. Following 10 sec adaptation to acetic acid, the phasic responses to Q-HCl and Q-H2SO4 were… (More)
After frog taste cells were adapted to 1 mM quinine-HCl (Q-HCl) for 10 sec, modification of receptor potentials in the taste cells induced by salt, acid, sugar and bitter stimuli was studied with microelectrodes. The phasic component of receptor potentials induced by 0.1 M NaCl, KCl, NH4Cl and MgCl2 was enhanced following adaptation to Q-HCl. The rate of… (More)
Prostaglandin E2 (PGE2) is well known as a mediator of inflammatory symptoms such as fever, arthritis, and inflammatory pain. In the present study, we evaluated the analgesic effect of our selective PGE2 synthesis inhibitor, compound I, 2-methyl-2-[cis-4-([1-(6-methyl-3-phenylquinolin-2-yl)piperidin-4-yl]carbonyl amino)cyclohexyl] propanoic acid, in rat… (More)
Off-responses in frog taste cells evoked by a Ringer rinse following 1 mM quinine-HCI (Q-HCl) stimulation were investigated with an intracellular recording technique. Three types of off-responses were found; a transient off-depolarization, a rebound-type off-depolarization and a transient off-hyperpolarization. The time to peak and duration of off-responses… (More)
The mean diameter of myelinated afferent fibers from the taste disk located on the frog tongue was 5.5 micrometers within the fungiform papillae and increased at a rate of 0.8 micrometers/cm length of fibers. A gradual increase in conduction velocity of single afferent fibers from the taste disk was confirmed electrophysiologically.
Following the suppression of renewal of rat taste cells by vinblastine sulphate, the preference for sucrose decreased markedly while the aversion to quinine did not change. The results suggest that the sensitivity of taste cells to sucrose decreases with their aging, but the sensitivity to quinine increases.