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Biomedical subjects

L M Beidler

Publications and source records attributed to L M Beidler.

At least 19 recordsLinked to original sources
PubMed1989

Sugar best single chorda tympani nerve fiber responses to various sugar stimuli in rat and hamster.

1. Sugar best single chorda tympani nerve fiber of rat and hamster were tested with six sugars. 2. Fibers were selected for this experiment, only if they responded to 1.0 M sucrose or 1.0 M maltose and they responded poorly to 0.1 M NaCl. 3. In rat, some single fibers gave larger responses to maltose than to sucrose, while in hamster nearly all nerve fibers responded best to sucrose. 4. The order of effectiveness of sugars was maltose greater than fructose greater than or equal to lactose greater than sucrose greater than glucose greater than galactose in rat and sucrose greater than fructose greater than or equal to glucose greater than or equal to galactose greater than maltose greater than lactose in hamster.

Animals↗
PubMed1988

A comparison of the effects of bilateral sections of the chorda tympani nerve and extirpation of the submaxillary and sublingual salivary glands on the eating and drinking patterns of the rat.

The chorda tympani nerve (CT) innervates the fungiform papillae on the tip of the tongue and has been considered an important nerve for the sense of taste. The CT also contains the parasympathetic supply to the submaxillary and sublingual salivary glands. Therefore, changes in taste or feeding behavior following bilateral sections of CT are caused by both degeneration of fungiform papillae and the inevitable partial desalivation of the rat. In the present experiments we compared the effects of bilateral chorda tympani nerve sections with extirpation of submaxillary and sublingual glands on daily home cage eating and drinking patterns in the rat. Before and after surgery we analyzed the daily eating and drinking patterns, including such measures as intake, bout number, bout length, interbout interval and rate of consumption during bouts. The results of desalivation and bilateral CT sections were indistinguishable. The most profound change was that eating bout duration was increased following surgery. Since food intake did not increase, the results indicate a marked loss in eating efficiency over the daily ingestion periods. Although the eating patterns of desalivated and chorda tympani sectioned rats are quite similar, the evidence is not compelling that they have the same physiological basis. A second experiment was designed to test the hypothesis that the atypical eating patterns observed following bilateral sectioning of CT were the direct result of partial desalivation resulting from the denervation of the salivary glands. In this experiment a unilateral section was made of one CT and it was shown that the eating behavior was not affected. Then the contralateral submaxillary and sublingual salivary glands were removed. This resulted in a six-fold increase in feeding bout length. In all cases a unilateral CT section combined with extirpation of the contralateral salivary glands resulted in rats whose eating behavior was indistinguishable from the earlier data following either the bilateral CT sections or bilateral desalivations. The conclusion is drawn that the eating irregularities noted following bilateral CT sections result from this partial desalivation. CT sections were verified by taste bud counts in the fungiform papillae and histological examinations were made of salivary glands in rats receiving CT sections.

Animals↗
PubMed1987

The effect of bilateral sectioning of the chorda tympani and the greater superficial petrosal nerves on the sweet taste in the rat.

The effects of bilateral deafferentation of the greater superficial petrosal (GSP) and the chorda tympani (CT) nerves on the ingestion of sucrose solutions were studied in rats. The rats received five daily sequential 30 second exposures for each sucrose concentration, and the average number of licks per exposure was calculated. Sucrose concentrations of 0.01, 0.03, 0.10, 0.32, and 1.00 M were presented in ascending order across days, both before and after bilateral sectioning of both the CT and the GSP nerves, the CT alone, the GSP alone, or a sham surgery. Prior to surgery, mean lick rate increased with increasing concentrations of sucrose. Following surgery, the rats with combined GSP and CT nerve sections showed a significant decrease in mean rate of licking to the sucrose solutions. The rats with GSP sections showed a similar decrease in mean lick rate to the sucrose solutions. Animals with sections of the CT nerve and sham-operated animals showed no significant reduction in mean lick rate to the sucrose solutions. These results indicate that the GSP nerve is important to the rat in reinforcing high lick rates to sucrose.

Animals↗
PubMed1985

Response characteristics of three taste nerves in mice.

Gustatory responses from 3 nerves, the chorda tympani, glossopharyngeal and superior laryngeal nerves were investigated in the mouse. Stimuli were NH4Cl, NaCl, KCl, HCl, quinine-HCl, sucrose, urea, glucose and distilled water. The 3 nerves responded differently to these stimuli. The chorda tympani responded strongly to HCl and sucrose, but weakly to quinine-HCl, while the glossopharyngeal responded well to quinine-HCl rather than to either HCl or sucrose. The order of effective stimulation was NH4Cl greater than NaCl greater than KCl for the chorda tympani, whereas NH4Cl greater than KCl greater than NaCl for the glossopharyngeal nerve. The responses of the superior laryngeal nerve were remarkably different from those of the others. Water was the most effective stimulus for the nerve and the response to water was depressed by either electrolytes or non-electrolytes added in water. These results suggest dissimilar contributions of the 3 nerves to the physiological functions.

Animals↗
PubMed1984

Studies in canine olfaction, taste and feeding: a summing up and some comments on the academic-industrial relationship.

The authors discuss two principal points. First, what appear to be contradictory findings in the feeding studies in this monograph can be resolved by clarifying two terms: palatability and preference. Second, some of the work in the monograph resulted from an academic and industrial relationship. This relationship was judged mutually beneficial and productive. The primary benefits are discussed along with what are considered the key ingredients for a successful joint venture.

Animal Feed↗
PubMed1983

Dependence of gustatory neural response on depolarizing and hyperpolarizing receptor potentials of taste cells in the rat.

The rat taste cells responded to the four basic taste stimuli (0.5 M NaCl, 0.02 M quinine-HCl (Q-HCl), 0.01 M HCl and 0.5 M sucrose) with depolarizing or hyperpolarizing receptor potentials. The rates of obtaining hyperpolarizing responses under 41.1 mM NaCl adaptation were 3% for NaCl, 42% for Q-HCl, 21% for HCl and 37% for sucrose. Most of the taste cells responded to more than two kinds of taste stimuli. The ratio of mean magnitudes of depolarizing and hyperpolarizing responses for the four basic taste stimuli under 41.4 mM NaCl was as follows: NaCl:Q-HCl:HCl:sucrose = 100:9:48:2. The ratio of mean magnitudes of tonic chorda tympani nerve responses for the four basic taste stimuli under 41.4 mM NaCl was: NaCl:Q-HCl:HCl:sucrose = 100:5:37:2. Comparison of both taste cell and nerve responses suggests that the depolarization of a taste cell is concerned with a generation of gustatory neural impulses, and that the hyperpolarization is concerned with a depression of the impulses.

Action Potentials↗
PubMed1983

Response characteristics of rat taste cells to potassium benzoate.

The rat taste cells responded to K-benzoate solutions higher than the threshold concentrations (0.03-0.3 M) with a depolarizing receptor potential, but they responded to K-benzoate lower than the thresholds with a hyperpolarizing receptor potential. In either depolarizing or hyperpolarizing receptor potentials the rise time decreased with increasing amplitude, but the fall time increased with increasing amplitude. During generation of either depolarizing or hyperpolarizing receptor potentials the input resistance of taste cells decreased with increasing amplitude. Application of the mixtures of various concentrations of NaCl and 0.05 M K-benzoate resulted in a reduction of receptor potential amplitude, as compared with that evoked by application of NaCl alone. It is concluded that a depression of gustatory neural impulse frequency by low concentrations of K-benzoate is mainly due to the hyperpolarizing receptor potential of taste cells elicited by the K-benzoate solutions.

Animals↗
PubMed1982

The response characteristics of rat taste cells to four basic taste stimuli.

1. The shapes of receptor potentials of rat taste cells in response to the four basic taste stimuli (0.5 M NaCl, 0.02 M quinine-HCl (Q-HCl), 0.01 M HCl and 0.5 M sucrose) were classified into three types, i.e. (1) a depolarization alone, (2) a depolarization preceded by a transient hyperpolarization and (3) hyperpolarization alone. 2. The rise and fall times of depolarizing responses to NaCl were much shorter than those to the other three stimuli. The fall time of depolarization evoked by HCl was the longest. The rise and fall times of all hyperpolarizing responses were shorter than those of all depolarizing responses. 3. The input resistance of taste cells decreased during depolarizations elicited by NaCl stimulation, but increased during depolarizations and hyperpolarizations elicited by stimulation with Q-HCl, HCl and sucrose. 4. The taste stimulus-induced input resistance change returned faster to the control in the order of NaCl greater than sucrose greater than Q-HCl greater than HCl when the stimulus was rinsed from the tongue. 5. From these response characteristics the rat taste cells responding to each of the four basic taste stimuli are largely divided into two types, low-sensitive taste cell and high-sensitive taste cell.

Animals↗
PubMed1979

Receptor potential of rat taste cell to potassium benzoate.

Rat taste cells responded to relatively low concentrations of K-benzoate with a hyperpolarization and to the high concentrations with a depolarization. During both responses the membrane resistance of a taste cell decreased. Depolarization elicited by application of a combination of 0.25 M NaCl and 0.05 M K-benzoate was smaller than that by the NaCl alone, indicating a depressant action of K-benzoate.

Animals↗
PubMed1977

Differences in the composition of the polypeptides deposited in the axon and the nerve terminals by fast axonal transport in the garfish olfactory nerve.

Proteins transported by the fast wave of axonal transport have been shown to be deposited both in the axon and in the nerve terminals. Differences in the nature of the molecules deposited in these two areas were studied in the garfish olfactory system. In order to avoid analysis of transported molecules in two different types of tissue like the olfactory nerve and the olfactory bulb, the study was conducted (1) by comparing the composition of the moving crest of radioactivity at two different points along the nerve: when the crest enters the axon and when it reaches a distance of approximatively 5 cm from the nerve endings, (2) by determining the composition of the molecules remaining in the axon behind the moving crest. Three subcellular fractions (two membranous fractions and a mitochondrial pellet) were investigated. In both membranous fractions the majority of the polypeptides deposited in the axon ranged from 50 to 150,000 daltons. No outstanding peak of radioactivity was found in either fraction. Radioactivity was relatively evenly distributed among the various polypeptides. In the lightest membranous fraction, however, a peak (mol. wt., 54-58,000) was more particularly deposited in the axon. The opposite situation was found for the molecules moving toward the synapses: transported radioactivity was concentrated in a few distinct polypeptides, while the others were significantly less labeled. Three peaks were found in the lightest membranous fraction (mol. wt., 35,000, 54-58,000 and 126,000). Only two peaks were determined in the heaviest fraction (mol. wt., 58,000 and 126,000). The 126,000 mol. wt. peak increases with distance in both membranous fractions from 9 to 12% of the total radioactivity and moves mainly toward the synapses. The 35,000 mol. wt. polypeptide presented some interesting properties: it was found in larger quantities in the lightest membranous fraction; labeling was very poor in the heaviest membranous fraction, and finally this polypeptide appeared to be largely transported to the synapses. Results concerning the polypeptide composition and the composition of the transported molecules indicated that the lightest fraction may contain more synaptosomal material. From this study it appears that most transported polypeptides are distributed in both the axon and the nerve terminals, but that the percentage delivered to each area varies. A few distinct polypeptides on the contrary are more selectively transported to the synapses and are even differently localized in subcellular fractions.

Animals↗
PubMed1975

Distribution along the axon and into various subcellular fractions of molecules labeled with (3H)leucine and rapidly transported in the garfish olfactory nerve.

The distribution of molecules labeled with [3H]leucine by fast axoplasmic transport in vivo has been studied in the garfish olfactory nerve after incorporation of the amino acid by the olfactory mucosa. Owing to the size of the nerve, it has been possible to follow the fate of the labeled molecules in 10 different subcellular fractions of 6 consecutive nerve segments. Each segment represents a different part of the profile developed by the transported radioactive molecules. In order to determine the influence of the perikaryon (rate of protein synthesis and rate of protein release into the axon) transport was studied under 3 different conditions: (1) intact nerves (simply labeled with [3H]leucine); (2) nerves cut from the cell bodies 6 h after application of [3H]leucine; and (3) nerves pulse-chase labeled for 1 h. Several conclusions can be drawn. (1) The bulk of the rapidly transported molecules are membranous axonal proteins, as determined by enzyme markers. Most are found in subcellular fractions representing 17% of the total axonal protein. They are synthesized very rapidly in the cell bodies (less than 1 h after isotope deposition) and exhibit the highest specific activities measured. These high specific activities were found in the same axonal membrane fractions in both plateau and crest, suggesting that the membrane precursors are transported as particles rather than as subunits. (2) The majority of these proteins are released into the axon immediately after synthesis; however, at least 30% of the labeled axonal membranous proteins are not released with the fast wave itself but progressively over a long period of time. (3) The majority of the moving material, particularly in membranous fractions, is left behind the fast wave and is deposited in the axon. When the front base of the fast wve has covered 70% of the total nerve length, only 19% of the labeled material of the main axonal membranous fraction appears still to be moving. (4) Proteins with high specific activities are found near the cell bodies and may be the result of early axonal transport of amino acids, diffusing later into the surrounding cells and being incorporated into proteins. Some free amino acids are also transported along the axon.

Acetylcholinesterase↗
PubMed1975

A quantitative analysis of isotope concentration profiles and rapid transport velocities in the C-fibers of the garfish olfactory nerve.

In the olfactory nerve of the long-nosed garfish (Lepisosteus osseus), unusually well-defined isotope concentration distributions can be established with the rapid transport process. Transport velocities of two profile loci can be accurately described and a quantitative profile analysis is possible after profile normalization. Results from such studies indicate that: (1) peak amplitudes decrease exponentially as a function of distance from the olfactory mucosa according to the equation p = 2130 exp (-0.109chi); (2) the wavefront base and the peak apex loci move at rates of 221 +/- 2 and 201 +/- 4 mm/day, respectively (at 23 degrees C), revealing a peak dispersion or broadening during transport; (3) the broadening is asymmetric with material shifting to the rear of the peak; (4) plateau regions are established behind the peak with material deposited by the peak; (5) only 20% of the total radioactivity in a cut nerve reaches the nerve terminals in the rapid transport peak while 80% is deposited along the axon; (6) profile areas from cut nerves decrease and lose 15% of their activity in 20 hr, while intact nerve profiles increase 10% in 16 hr due to continued somal contribution to the profile; (7) the displacement of the wavefront base (WFB) and peak apex (PA) profile loci can be described by the functions s(WFB) = (0.055T - 0.345)t - 1.43 s(PA) = (0.053T - 0.391)t - 2.71 (8) transport velocities are linear functions of temperature between 10 and 25 degrees C and increase 370% in that range. A linear extrapolation of the WFB and PA functions to 37 degrees C yields 410 and 377 mm/day, respectively.

Animals↗
PubMed1975

Membrane resistance change of the frog taste cells in response to water and Nacl.

The electrical properties of the frog taste cells during gustatory stimulations with distilled water and varying concentrations of NaCl were studied with intracellular microelectrodes. Under the Ringer adaptation of the tongue, two types of taste cells were distinguished by the gustatory stimuli. One type, termed NaCl-sensitive (NS) cells, responded to water with hyperpolarizations and responded to concentrated NaCl with depolarizations. In contrast, the other type of cells, termed water-sensitive (WS) cells, responded to water depolarizations and responded to concentrated NaCl with hyperpolarizations. The membrane resistance of both taste cell types increased during the hyperpolarizing receptor potentials and decreased during the depolarizing receptor potentials, Reversal potentials for the depolarizing and hyperpolarizing responses in each cell type were a few millivolts positive above the zero membrane potential. When the tongue was adapted with Na-free Ringer solution for 30 min, the amplitude of the depolarizing responses in the NS cells reduced to 50% of the control value under normal Ringer adaptation. On the basis of the present results, it is concluded (a) that the depolarizing responses of the NS and WS cells under the Ringer adaptation are produced by the permeability increase in some ions, mainly Na+ ions across the taste cell membranes, and (b) that the hyperpolarizing responses of both types of taste cells are produced by a decrease in the cell membrane permeability to some ions, probably Na+ ions, which is slightly enhanced during the Ringer adaptation.

Adaptation, Physiological↗