Effect of extracellular fluid volume expansion on the interparabronchial septum of the avian lung

Scanning electron microscopy was used to examine the interparabronchial septa of chickens as a potential site of lymphatic drainage in the avian lung. Anaesthetized chickens were subjected to extracellular fluid volume expansion to produce pulmonary oedema as a result of increased capillary fluid flux into the interstitial spaces of the lung. In normal (control) chickens, the adjacent parabronchi were separated by a minimal septal space. In the "volume-loaded" birds, however, the interparabronchial septal spaces were measurably thickened and engorged as a result of hydrostatic pulmonary oedema. These results, which were consistent with reports of the effect of hydrostatic pulmonary oedema in mammals, suggest that the interparabronchial septum is a potential route of lymphatic drainage in the avian lung.     

Meckel's diverticulum. I. Extramedullary myelopoiesis in the yolk sac of hatched chickens (Gallus domesticus)

We have described an extramedullary myelopoietic tissue located in the wall of the yolk sac. This myelopoietic site is absent at hatch and it produces only granulocytic and monocytic cells during the regression of the yolk sac from 2 to 7 weeks of age. The granulocytic and monocytic cells are located in two distinct zones. The monocytic cells migrate close to the lumen of the yolk sac where they may fuse and form giant cells. There are no mature granulocytes present. Cell migration has not been observed. Therefore, the fate and function of the young granulocytic cells are unknown. In this extramedullary myelopoietic tissue, the absence of erythrocyte and thrombocyte formation may indirectly suggest that these cells develop together in sinuses that are lacking in the wall of the yolk sac.     

Intrapulmonary receptor response to changes in airway-gas composition in Gallus domesticus

1. A unidirectional, artificial ventilating system was used to observe respiratory and neural responses to changes in CO(2) concentration in pulmonary airways of the chicken.2. Sectioning any of the three pulmonary branches of the vagus slowed the respiratory response to sudden removal of CO(2) from unidirectional ventilating gas stream.3. The impulse frequency of CO(2)-sensitive units was inversely related to the CO(2) content in the ventilating gas stream.4. Abrupt elimination of CO(2) from the ventilatory gas stream caused a transient burst of activity from CO(2)-sensitive receptors, which quickly adapted to a constant discharge frequency. Fifty percent of the units responded within 0.35 sec after CO(2)-free gas reached the lungs. The neural response to abrupt re-addition of CO(2) to the gas stream was less rapid.5. Acetylcholine or NaCN injected into the pulmonary artery had no apparent effect on the discharge of CO(2)-sensitive receptors. Veratridine temporarily reduced discharge and occasionally produced short, rapid bursts of activity.6. Hypoxia and hyperoxia (5% and 80% O(2)) produced no significant change in the discharge of CO(2)-sensitive receptors.7. Carbon dioxide-sensitive units in spontaneously breathing chickens were silenced by adding 10% CO(2) to the inspired gas; the units responded vigorously to inflation of the respiratory system with a gas containing no CO(2) but remained silent during inflation with gas containing 15% CO(2). Units insensitive to CO(2), which increased their impulse frequency during inflation regardless of the CO(2) content of the inflating gas, also were observed.     

Regulation of extracellular fluid volume and osmolality

In health, both the total amount and the distribution of water and electrolytes in the body are controlled within narrow limits. While intercompartmental water fluxes depend solely on physical driving forces, the latter are determined by complex circulatory feedback mechanisms that manipulate capillary pressure, and by active transport mechanisms that affect intracellular osmotic pressure. Fluid and electrolyte intake are determined by central neural mechanisms. However, the fine tuning of body fluid and elctrolyte contact is accomplished by alterations in renal excretion controlled by a variety of local (intrarenal) mechanical and endocrine processes, as well as external neural endocrine feedback systems that include the antidiuretic hormone and the renin-angiotensin-aldosterone systems. Analysis of renal control is complicated by multiple interactions among the different control systems.     

Influence of extracellular fluid volume expansion on magnesium,calcium and phosphate handling along the rat nephron

Summary Renal tubular handling of P, Ca, Mg and Na was studied in the rat both before and during mild hypertonic NaCl loading (ECVE), using micropuncture and clearance techniques and electron microprobe analysis. Micropuncture was performed at the late proximal and early distal tubule sites. ECVE significantly increased the urinary output of all four elements. In the case of Mg, the increase was relatively small and dependend of reabsorption all along the entire length of the nephron. For Ca, it depended on the inhibition of proximal reabsorption, partially compensated by increased reabsorption along the loop. For P, it depended on proximal inhibition, no important net phosphate movement occuring in the loop during both periods. Ca reabsorption was highly correlated to that of sodium along the proximal tubule and Henle's loop. This was not the case for Mg and P. In the loop, Ca and Mg reabsorption were closely related to the load delivered at the beginning of the structure. These observations are compatible with the view that tubular reabsorption of Ca and Mg is concentration rather than Tm limited, and that reabsorption of Ca, unlike that of Mg, is linked to the movements of sodium. Following ECVE, the difference between early distal and urinary deliveries increased significantly for Ca and P, but not for Mg. For phosphate, this difference accounted for by 45% of the delivery at the early distal tubule site, at variance with microinjection data obtained in the rat under similar salt loading conditions, which indicated that 17% only of the phosphate distal delivery were reabsorbed along the terminal segments. This discrepancy is discussed in terms of nephron functional heterogeneity.Collaborateur temporaire de thèse C.E.A.     

Sustained and generalized extracellular fluid expansion following heat acclimation

We measured intra- and extravascular body-fluid compartments in 12 resting males before (day 1; control), during (day 8) and after (day 22) a 3-week, exercise–heat acclimation protocol to investigate plasma volume (PV) changes. Our specific focus was upon the selective nature of the acclimation-induced PV expansion, and the possibility that this expansion could be sustained during prolonged acclimation. Acclimation was induced by cycling in the heat, and involved 16 treatment days (controlled hyperthermia (90 min); core temperature = 38.5°C) and three experimental exposures (40 min rest, 96.9 min ( s.d. 9.5 min) cycling), each preceded by a rest day. The environmental conditions were a temperature of 39.8°C ( s.d. 0.5°C) and relative humidity of 59.2% ( s.d. 0.8%). On days 8 and 22, PV was expanded and maintained relative to control values (day 1: 44.0 ± 1.8; day 8: 48.8 ± 1.7; day 22: 48.8 ± 2.0 ml kg⁻¹; P < 0.05). The extracellular fluid compartment (ECF) was equivalently expanded from control values on days 8 (279.6 ± 14.2 versus 318.6 ± 14.3 ml kg⁻¹; n = 8; P < 0.05) and 22 (287.5 ± 10.6 versus 308.4 ± 14.8 ml kg⁻¹; n = 12; P < 0.05). Plasma electrolyte, total protein and albumin concentrations were unaltered following heat acclimation ( P > 0.05), although the total plasma content of these constituents was elevated ( P < 0.05). The PV and interstitial fluid (ISF) compartments exhibited similar relative expansions on days 8 (15.0 ± 2.2% versus 14.7 ± 4.1%; P > 0.05) and 22 (14.4 ± 3.6% versus 6.4 ± 2.2%; P = 0.10). It is concluded that the acclimation-induced PV expansion can be maintained following prolonged heat acclimation. In addition, this PV expansion was not selective, but represented a ubiquitous expansion of the extracellular compartment.     

Sleep in the domestic hen (Gallus domesticus)

Electrophysiological recordings were made of five closely observed hens, all permanently implanted with both EEG and EMG electrodes. Five behavioural postures were distinguished and percentages of wakefulness, sleep and presumably paradoxical sleep (PS) were determined during the third and sixth hour of the dark period. Substantial agreement was generally found between behaviour and sleep with the exception of sitting or standing motionless with at least one eye open. During two thirds of this behavioural posture, the EEG showed large amplitude slow waves undistinguishable from slow wave sleep. Characteristics of PS were determined: periods were short, whereas its percentage increased during the night. Furthermore, EMG atonia was never found. An all night recording was made, and delta activity (2-5 Hz) was filtered and plotted against time for three of the hens. A significant decrease in delta activity across the night was found. Differences and similarities between sleep in hens and in mammals are discussed. Although large similarities exist it is concluded that some properties of birds' sleep make it unique and are a challenge for further study.     

Retinal projections to the pretectum in the fowl (Gallus gallus domesticus)]

The retinal projection to the pretectum was examined in the adult domestic fowl by means of anterograde transport of horseradish peroxidase (HRP). At the same time, the cytoarchitecture of the pretectum was studied in Nissl preparation. Fifteen fowls (Gallus gallus domesticus) were used for the HRP study, and four were used for the cytoarchitectural study. One hundred microliters of a 30% HRP solution in physiological saline were injected into the vitreous body of the unilateral eye under sodium pentobarbital anesthesia (30 mg/kg body weight). After a postoperative period of 48 hours, the animals were deeply anesthetized and perfused intracardially with 1,000 ml of Ringer solution, followed by 2,000 ml of 1% paraformaldehyde and 1.25% glutaraldehyde in a 0.1 M phosphate buffer (pH 7.4) which was then followed by 1,000 ml of 10% sucrose in the same buffer. The brain was cut into serial transverse sections at 60 microns on a freezing microtome. Every section was treated with tetramethyl benzidine (TMB). Based on cytoarchitectural and HRP results, the pretectum of the adult hen was divided into the following eight nuclei: nucleus principalis pretectalis (P), nucleus subpretectalis (SP), nucleus principalis precommissuralis (PPC), nucleus medialis pretectalis (PTM), nucleus pretectalis dorsalis (APd), nucleus area pretectalis (AP), nucleus spiriformis lateralis (SPL), and nucleus spiriformis medialis (SPM). The SPL and SPM lay closely adjacent to each other, although the boundary between them can be easily defined in any section. Furthermore, the SPM could be divided into two subnuclei: the dorsal part of the SPM (SPMd) located just under the SMT and dorsomedial to the P, and the ventral part of the SPM (SPMv), which was located above the PPC and ventromedial to the P. Retinal projections were found in the APd, the PTM, the AP and the SPM, contralaterally. APd was the smallest nucleus among the pretectal nuclei lying just above the tractus septomesencephalicus (SMT) and received the heaviest retinal inputs. In the PTM, clear terminals were distributed over the whole of the nucleus, whereas strong labeled terminals were also found around the principal pretectal nucleus. Slight retinal inputs were found in the ventral part of the SPM. Furthermore, heavily labeled terminals were found in the medial part of the AP designated as the interstitial nucleus of the posterior commissure by Niimi. Terminals in the ventral part of the SPM and the medial part of the AP have not been reported in the previous studies in the chick and pigeon. There were no terminals in the contralateral P, SPL, SP, PPC, and the ipsilateral brain stem.     

Behavioral reactions to gustatory stimuli in young chicks (Gallus gallus domesticus)

Freely-moving, posthatch chicks were individually presented 2 concentrations each of quinine, citric acid, fructose, sucrose, sodium saccharin, and distilled water and their behavioral reactions were videotaped and analyzed. Already during the first posthatch day distinct rejection responses to quinine and citric acid could be recognized. Prolonged head shaking and beak clapping episodes were the most dominant features of these reactions. While responses to water and sweet stimuli could be interpreted as acceptance behaviors, the resolution was generally not fine enough to discriminate between reactions to the 2 different sweet concentrations of these stimuli or between them and water. When only water or sugar solutions were presented to other hatchlings in a single session, there was a suggestion of more definite acceptance behavior to some sweet stimuli as compared to water. It is concluded that the systems mediating aversive gustatory responses are present and functioning in posthatching chicks while acceptance responses, though present, are less discriminative among stimuli.     

Effects of extracellular volume expansion on the tubular reabsorption of glucose

Summary Clearance and intratubular injections of (¹⁴C) glucose were performed in glucose loaded rats, during control (C) and extracellular fluid volume expansion (VE) to 10% of body weight. VE resulted in a significant decrease in hematocrit from 47.50±1.06 to 38.80±1.14% and plasma protein from 6.23±0.25 to 4.13±0.21 gm/100ml. Glomerular filtration rate (GFR) increased by 51% from 1.06±0.07 to 1.60±0.35 ml/min. Fractional excretion of sodium increased significantly from 0.42±0.07 to 12.58±1.25%. Maximal glucose reabsorption (TmG) was unchanged from 3.47±0.42 to 3.29±0.41 mg/min. However, TmG/GFR decreased significantly from 3.14±0.22 to 1.94±0.21 mg/ml GFR. As compared to C, VE resulted in a significant increase in (¹⁴C) glucose recovery after injection into the early and late proximal tubules, from 63±3 to 81±2% and 82±2 to 88±1% respectively. After distal tubular injections (¹⁴C) glucose recovery was complete in both C and VE; early distal injection 97±1 vs 98±1%, late distal injection 98±1 vs 99±1%. These results indicate an inhibitory effect of VE on fractional glucose reabsorption in the superficial nephron. There is no evidence for glucose reabsorption in the superficial distal nephron during C and VE.     

Physiological changes during tonic immobility in Gallus gallus var domesticus

Physiological parameters were examined in the hen in response to the induction of tonic immobility (TI). The induction of TI was associated with EEG arousal, low shank temperature and elevated heart rate. However, shortly after the adoption of TI, the EEG showed a predominantly slow-wave deactivated pattern, muscle tone fell and sympathetic nervous activity was reduced, as indicated by declining heart rate and peripheral vasodilation. Core temperature remained constant at 42 degrees C throughout the immobility response. Several instances of EEG-behavioural dissociation were observed. The results are discussed in terms of "cut-off" and waning of the induced fear state.