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Biomedical subjects

M R Fedde

Publications and source records attributed to M R Fedde.

At least 91 records · Page 5Linked to original sources
PubMed1977

Identification of two populations of biogenic amine-containg cells in the mouse lung.

Two distinct populations of fluorogenic amine-containing cells were observed in the lungs of nine-week old mice: one with an intense yellow emission, which possible indicates the presence of serotonin; and one emitting a yellow-green fluorescence, which probably indicates the presence of a catecholamine such as dopamine or norepinephrine. Simultaneous identification of two different fluorogenic amine-containing cells, without pre-administration of a precursor to that amine, has not previously been reported. Such evidence of amine-containing cells demonstrated the success of the perfusion-freezing technique and established that cellular storage of fluorogenic amines does occur in vivo under normal physiological conditions. The function of such amine-containing cells has not been established; however, their location and the known physiological effects of amines would suggest regional control of ventilation/perfusion of the lung.

Animals↗
PubMed1977

Intrapulmonary receptors in the Tegu lizard: II. Functional characteristics and localization;.

Intrapulmonary receptors identified in the Tegu lizard by single-unit vagal recording (Fedde et al., 1977) were subjected to a number of stimuli and localized within the lung. Some carbon dioxide receptors could follow periodic changes in intrapulmonary CO2 concentrations as rapidly as 1.3 Hz; No oxygen sensitivity was observed with this receptor type, and halothane markedly depressed the discharge frequency. In response to intravenously injected acetazolamide they increased their discharge frequency and became almost totally insensitive to CO2, suggesting molecular per se is not the direct controller of receptor discharge; These receptors show many of the functional characteristics described for those in the avian lung. Afferent activity from both CO2 and mechanoreceptors could be elicited by electrically stimulating the lung surface. The CO2 receptors appeared to be organized in a receptive field covering more than 1 cm2 of lung surface, multiple receptors being innervated by a single afferent fiber. Activity in afferent fibers from mechanoreceptors could be evoked from only one distinct spot on the lung surface. Conduction velocities of afferent fibers from CO2 receptors ranged from 1 to 3 m-sec-1; from mechanoreceptors, from 1.9 to 5.2 m-sec-1.

Acetazolamide↗
PubMed1977

Evidence for mechanoreceptors in the muscular stomach of the chicken.

Single-fiber, vagal recordings were made from mechanoreceptors in the muscular stomach of the chicken. These receptors increased discharge frequency (i) during gentle compression of the wall of this organ and (ii) when coordinated contractions of the organ were induced pharmacologically.

Animals↗
PubMed1977

Histochemical studies of respiratory muscles of chicken.

The histochemical profiles of myofibrillar adenosine triphosphatase (ATPase), nicotinamide adenine dinucleotide diaphorase (NADDase), and phosphorylase (Pase) activities were studied in the respiratory muscles of the chicken. Most respiratory muscles contained fibers exhibiting 18 possible combinations of staining reactions (dark or light ATPase; dark, intermediate, or light NADDase; dark, intermediate, or light Pase). Fibers that stained light for ATPase constituted as little as 10% of the total population in rectus abdominis, but as much as 32% of the total in costosternalis pars major. Those fibers did not tend to be smaller than fibers that stained dark for ATPase in the respiratory muscles as a group. Assuming these staining characteristics are correlated with functional properties of the fibers, as they are in mammals, the majority of the fibers should contract rapidly (dark ATPase) and be fatigue resistant (dark and intermediate NADDase).

Adenosine Triphosphatases↗
PubMed1976

Response to CO2 of intrapulmonary chemoreceptors in the emu.

We studied discharge frequencies of 12 intrapulmonary chemoreceptors in the paleopulmonic lung of an emu (Dromiceius novaechollandiae) during unidirectional, artificial ventilation when step changes and static CO2 concentrations were given. Discharge frequency in afferent neurons from the receptors increased as intrapulmonary CO2 decreased. The response of the receptors to various static intrapulmonary CO2 concentrations was similar to that previously demonstrated for the duck and chicken. The median sensitivity of the emu receptors at one-half maximal discharge was 4.6 imp-(sec-0.01 F1CO2)-1. Discharge frequencies altered phasically in nine of 12 receptors when step changes in CO2 of 3.3% at 1.6 Hz were given in the unidirectional gas stream while four of 12 modulated their discharge when the CO2 changes were as rapid as 3.2 Hz. Hence, some receptors can respond to rapid fluctuations in CO2 in their microencironment. We conclude that intrapulmonary chemoreceptors in the paleopulmonic lung of the emu exhibit similar characteristics to those in birds that possess varying amounts of neopulmonic parabronchi, such as the duck and chicken.

Animals↗
PubMed1976

Intrapulmonary CO2 receptors in the duck: IV. Discharge pattern of the population during a respiratory cycle.

We used single-unit vagal recordings to study the average discharge pattern during a respiratory cycle from 57 intrapulmonary CO2 receptors in 6 ducks artificially ventilated with a Starling pump. Peak discharge frequency occurred during inspiration in 51%, expiration in 19%, and both inspiration and expiration in 30% of the receptors. Average discharge frequency from all receptors was maximum at mid-inspiration, but frequency also increased slightly during early expiration. The results suggest that the brain receives a discharge pattern from the total population of intrapulmonary CO2 receptors which is phasic with respiration. Such a signal may control the rate and amplitude of breathing.

Animals↗
PubMed1975

Evaluation of an indirect method for estimating myofiber number in transverse sections of skeletal muscle.

The total number of myofibers contained in the transverse sections of 6 canine pectineus muscles was counted, using direct- and indirect-counting methods. For the direct-counting method, the transverse section of each muscle was photographed, from which a montage of each section was constructed. Then, the total number of myofibers contained in each montage was counted. The number obtained by the direct-counting method was used to determine the accuracy of the indirect-counting method. For the indirect-counting method, 40 randomly selected areas in each section were photographed. Then, the total number of myofibers contained in the randomly selected areas of each section was counted. From these counts, the total number of myofibers contained in each transverse section was calculated after the entire cross-sectional area of each section was determined by planimetry. The indirect-counting method was performed 3 times for each section. By direct count, the number of myofibers in a section was between 12,368 and 163,223. Generally, the indirect-counting method tended to overestimate the number of myofibers per section. The mean percentage error of estimates plus or minus standard error for all muscles and trials was 3.89 plus or minus 1.17; the range was minus 6.17 to +11.97. The percentage errors of the indirect counts were significantly correlated with the number of myofibers/sq mm and total number of myofibers/section; for every 1,000 myofibers/sq mm or 100,000 myofibers/section, an error of 2 or 5%, respectively, can be anticipated. The indirect-counting method utilized 10 to 20% of the man-hour effort required by the direct-counting method.

Animals↗