Effect of hyperosmolarity on resting and developed tension in heart muscle

1977 ◽  
Vol 232 (3) ◽  
pp. C155-C162 ◽  
Author(s):  
F. F. Vargas ◽  
J. A. Johnson
Keyword(s):  
Weight Loss ◽  
Rabbit Heart ◽  
Ringer Solution ◽  
Base Line ◽  
Initial Value ◽  
Tension Level ◽  
Resting Tension ◽  
Tension Recovery ◽  
Initial Drop ◽  
Line Level

Simultaneous changes in weight, tension, and electrical activity were studied in the isolated perfused rabbit heart when the Ringer solution perfusion fluid was made hypertonic by the addition of sucrose, urea, glycerol, ethylene glycol, or formamide. The typical responses to each of the molecules was an initial drop in weight and tension followed by a return toward the base-line level. A 0.4 M concentration of sucrose, urea, or glycerol reduced the weight to 40 +/- 4.6, 48 +/- 3, and 52.2 +/- 3% of the initial value, respectively. The tension was simultaneously reduced to 23 +/- 3.5, 31 +/- 2, and 41 +/- 4% of its initial value. The tension drop produced by the solutes tested was linearly related to the amount of water lost by the heart. The falling phases of both tension and weight loss were closely correlated phases of both tension and weight loss were closely correlated in time a magnitude and were both related to the effectiveness of a particular molecule to move water out of the cells. In contrast, the subsequent rising phases of tension and weight were not as well correlated in time and magnitude. Whereas for most of the molecules used, the tension recovery was incomplete; urea, in contrast, caused an overshoot of the control tension level, thus pointing toward a unique inotropic effect of this compound. Resting tension rose for both urea and sucrose but not for the other compounds.

scholarly journals An Estimate of Reflection Coefficients for Rabbit Heart Capillaries

1964 ◽  
Vol 47 (4) ◽  
pp. 667-677 ◽  
Author(s):  
Fernando Vargas ◽  
John A. Johnson
Keyword(s):  
Weight Change ◽  
Rabbit Heart ◽  
Ringer Solution ◽  
Reflection Coefficients ◽  
Test Substance ◽  
Time Rate ◽  
Loss Of Weight ◽  
Test Molecule ◽  
Zero Time ◽  
Heart Capillaries

Isolated perfused rabbit hearts have been used to determine the reflection coefficients, σ, of the heart capillaries to certain lipoid-insoluble substances. This was done by initially perfusing the heart with a Ringer solution containing no test molecule and then suddenly switching to a solution which differed from the original only by containing a small amount of test substance. This produced a loss of weight of the heart which was continuously recorded as a function of time. Taking the "zero" time rate of weight change and using an equation given by Kedem and Katchalsky reflection coefficients for urea, sucrose, raffinose, and inulin were obtained. These turned out to be 0.1, 0.3, 0.38, and 0.69 respectively. Using the approach of Durbin and Solomon equivalent pore radii were estimated to be about 35 Angstroms.

Effects of hypercapnia and hypoxia on abdominal expiratory nerve activity

1983 ◽  
Vol 55 (5) ◽  
pp. 1614-1622 ◽  
Author(s):  
J. F. Ledlie ◽  
A. I. Pack ◽  
A. P. Fishman
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Neural Activity ◽  
Intravenous Infusion ◽  
Base Line ◽  
Medial Branch ◽  
Plateau Phase ◽  
Nerve Activity ◽  
Proprioceptive Inputs ◽  
Line Level

We examined the effects of progressive hypercapnia and hypoxia on the efferent neural activity in a whole abdominal expiratory nerve (medial branch of the cranial iliohypogastric nerve (L1) in anesthetized, paralyzed dogs. To eliminate effects of phasic lung and chest-wall movements on expiratory activity, studies were performed in the absence of breathing movements. Progressive hyperoxic hypercapnia and isocapnic hypoxia were produced in the paralyzed animals by allowing 3-5 min of apnea to follow mechanical ventilation with 100% O2 or 35% O2 in N2, respectively; during hypoxia, isocapnia was maintained by intravenous infusion of tris(hydroxymethyl)aminomethane buffer at a predetermined rate. To quantify abdominal expiratory activity, mean abdominal nerve activity in a nerve burst was computed by integrating the abdominal neurogram and dividing by the duration of the nerve burst. Hypercapnia and hypoxia both increased mean abdominal nerve activity and decreased expiratory duration. In contrast to the ramplike phrenic neurogram, the abdominal neurogram consisted of three phases: an initial rising phase, a plateau phase in which abdominal nerve activity was approximately constant, and a terminal declining phase in which the activity returned to the base-line level. The height of this plateau phase and the rates of rise and decline of abdominal nerve activity all increased with increasing hypercapnia and hypoxia. We conclude that, with proprioceptive inputs constant, both hypercapnia and hypoxia are excitatory to abdominal expiratory neural activity.

Time course of the bronchoconstriction induced by inhaled histamine and methacholine

1983 ◽  
Vol 54 (3) ◽  
pp. 821-826 ◽  
Author(s):  
A. Cartier ◽  
J. L. Malo ◽  
P. Begin ◽  
M. Sestier ◽  
R. R. Martin
Keyword(s):  
Flow Resistance ◽  
Time Course ◽  
Recovery Phase ◽  
Base Line ◽  
Prolonged Action ◽  
Initial Value ◽  
Pulmonary Flow ◽  
The Mean

Eleven asthmatic subjects inhaled doubling concentrations of histamine until a near sixfold increase in total pulmonary flow resistance had been reached. This last concentration (C6) of histamine and methacholine was administered on two subsequent separate visits. Specific lung conductance (sGL) dropped to 18.6 +/- 7.9 (SD) and 19.1 +/- 10.3% of initial value after histamine and methacholine, respectively (NS). Whereas the peak action occurred in a similar interval (1–4 min), the mean duration of the subsequent plateau, defined as values of sGL within 20% of the maximum fall was 16.8 +/- 9.8 min for histamine and 74.6 +/- 53.7 min for methacholine (P less than 0.01). The recovery phase from the end of the plateau to base line lasted 25.5 +/- 14.4 min for histamine and 56.7 +/- 38.3 min for methacholine (P less than 0.01). The duration of plateau and recovery phases were not linked with base-line sGL, maximum fall in sGL, or C6. We conclude that for the same induced bronchoconstriction methacholine has a more prolonged action than histamine.

Neurotransmitters and biphasic respiratory response to hypoxia

1984 ◽  
Vol 57 (1) ◽  
pp. 213-222 ◽  
Author(s):  
W. A. Long ◽  
E. E. Lawson
Keyword(s):  
Phrenic Nerve ◽  
Initial Increase ◽  
Base Line ◽  
Respiratory Response ◽  
Biphasic Response ◽  
Controlled System ◽  
Initial Exposure ◽  
End Tidal ◽  
Line Level ◽  
End Tidal Co2

Recent work from this laboratory (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 55:483–488, 1983) has shown that the biphasic respiratory response to hypoxia in piglets is due to changing central neural respiratory output. To test the hypothesis that either adenosine or opiatelike neurotransmitters mediate the failure to sustain hyperpnea in response to hypoxia, 12 piglets were studied ata mean age of 2.9 +/- 0.4 days (range 2–6 days). Animals were anesthetized, paralyzed, and ventilatedusing a servo-controlled system that maintained end-tidal CO2 constant. Electrical activity of the phrenic nerve was recorded as the index of breathing. An initial experimental trial of 6 min ventilation with 15% O2 was performed in all 12 piglets. Thereafter all 12 piglets were treated with aminophylline (n = 6), naloxone (n = 3), or naltrexone (n = 3) and again subjected to 15% O2. During initial exposure to hypoxia there was an initial increase in phrenic activity that was not sustained. During recovery ventilation with 100% O2, phrenic activity transiently declined below the base-line level and then gradually returned. Subsequent intravenous administration of aminophylline, naloxone, or naltrexone caused base-line phrenic activity to increase. Thereafter repeat exposures to 15% O2 were carried out. During these posttreatment trials of hypoxia, phrenic activity further increased, but the hyperventilation was again not sustained. These findings suggest it is unlikely that either adenosine or mu-endorphin neurotransmitters are the primary mediators of the biphasic response to hypoxia in newborns.

Low sodium attenuation of the Ca2+ paradox in the newborn rabbit myocardium

1985 ◽  
Vol 248 (3) ◽  
pp. H345-H349
Author(s):  
S. Uemura ◽  
H. Young ◽  
S. Matsuoka ◽  
J. M. Jarmakani
Keyword(s):  
Rabbit Heart ◽  
High Energy ◽  
Adult Rabbit ◽  
High Energy Phosphates ◽  
Mechanical Function ◽  
High Energy Phosphate ◽  
Newborn Rabbit ◽  
Low Sodium ◽  
Resting Tension ◽  
Rabbit Myocardium

The effect of low sodium (Na 24 mM) perfusate during Ca2+ depletion on mechanical function, tissue high-energy phosphate, creatine kinase (CK) release, and tissue potassium was studied in the arterially perfused newborn and adult rabbit heart. During Ca2+ depletion, the time for DT and +dT/dtmax to decline to half-maximal value in newborn muscles perfused with low Na (46 +/- 3 S) was significantly (P less than 0.05) longer than the value obtained with normal Na (14 +/- 1 S). Similar values were obtained in the adult. During Ca2+ repletion, the increase in resting tension and CK release was attenuated in the low Na groups, and the values in the newborn were significantly less than in the adult. The recovery of +dT/dtmax and tissue high-energy phosphates in the low Na groups were significantly greater than in the normal Na groups, and the values in the newborn were significantly greater than in the adult. These data suggest that low Na during the Ca2+-free period delays both cellular Ca2+ depletion during the Ca2+-free period and Ca2+ influx during Ca2+ repletion. This effect in the newborn is greater than in the adult and might be explained by Na+-Ca2+ exchange.

Absence of transepithelial anion exchange by rabbit OMCD: evidence against reversal of cell polarity

1988 ◽  
Vol 255 (2) ◽  
pp. F220-F228 ◽  
Author(s):  
M. Hayashi ◽  
V. L. Schuster ◽  
J. B. Stokes
Keyword(s):  
Anion Exchange ◽  
Cell Polarity ◽  
Rate Coefficient ◽  
Collecting Duct ◽  
Ringer Solution ◽  
Base Line ◽  
Cortical Collecting Duct ◽  
Exchange System ◽  
Outer Medulla ◽  
Medullary Collecting Duct

In the rabbit cortical collecting duct (CCD), Cl tracer crosses the epithelium predominantly via an anion exchange system that operates in either a Cl-Cl or Cl-HCO3 exchange mode. In the present study, we used the 36Cl lumen-to-bath rate coefficient (KCl, nm/s), a sensitive measurement of CCD transepithelial anion transport, to investigate the nature of Cl transport in the medullary collecting duct dissected from inner stripe, outer medulla (OMCD). The KCl in OMCD perfused and bathed in HCO3-Ringer solution was low (46.2 +/- 8.5 nm/s) and similar to that value observed in the CCD when anion exchange is inhibited and Cl permeates the epithelium by diffusion. Unlike KCl in CCD, KCl in OMCD was not stimulated by adenosine 3',5'-cyclic monophosphate (cAMP). OMCD KCl was not altered by bath Cl and/or HCO3 removal, demonstrating the absence of transepithelial Cl-Cl and Cl-HCO3 exchange. To test the hypothesis that metabolic alkalosis could reverse the polarity of intercalated cells and thus induce an apical Cl-HCO3 exchanger in H+-secreting OMCD cells, we measured KCl in OMCD from rabbits made alkalotic by deoxycorticosterone and furosemide. Although the base-line KCl was slightly higher than in OMCD from control rabbits, the value was still far lower than the KCl under comparable conditions in CCD. Moreover, KCl in OMCD from alkalotic rabbits was unchanged by cAMP, or by sequential removal of bath HCO3 and Cl. Immunocytochemistry using peanut lectin and a monoclonal antibody to-erythrocyte band 3 failed to reveal any evidence for alkalosis-induced reversal of either CCD or OMCD intercalated cell polarity.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals DIETARY EFFECTS ON ANEMIA PLUS HYPOPROTEINEMIA IN DOGS

1949 ◽  
Vol 89 (3) ◽  
pp. 359-368 ◽  
Author(s):  
F. S. Robscheit-Robbins ◽  
G. H. Whipple
Keyword(s):  
Weight Loss ◽  
Plasma Protein ◽  
Protein Production ◽  
Wheat Gluten ◽  
Peanut Flour ◽  
Blood Protein ◽  
Base Line ◽  
Total Blood ◽  
Dietary Effects ◽  
Hemoglobin Production

Casein (purified or commercial) in this type of experiment falls in the top bracket as a protein consistently favorable for maximal new hemoglobin and plasma protein production in doubly depleted dogs (anemic and hypo-proteinemic). Lactalbumin is less favorable for total blood protein production and the ratio of plasma protein to hemoglobin is high—that is lactalbumin favors plasma protein production as compared with casein, or is less favorable for hemoglobin production. Peanut flour (purified or commercial) is less than half as effective as casein in promoting new blood protein production. The ratio of plasma protein to hemoglobin is about the same as casein. Wheat gluten as tested is distasteful to dogs. It is neither very good nor very poor for blood protein production when it is eaten. There is nothing unusual about the response. Weight loss usually confuses the picture. Liver stands as a control base line for the above experiments. Its capacity to further hemoglobin and plasma protein production is well established. The production of hemoglobin was about 3 times that of plasma protein in the experiments.

Rapid up- and down-regulation of pheromone signalling due to trail crowding in the ant Lasius niger

Behaviour ◽  
2014 ◽  
Vol 151 (5) ◽  
pp. 669-682 ◽  
Author(s):  
Tomer J. Czaczkes ◽  
Christoph Grüter ◽  
Francis L.W. Ratnieks
Keyword(s):  
Cuticular Hydrocarbons ◽  
Social Insects ◽  
Glass Beads ◽  
Lasius Niger ◽  
Base Line ◽  
Baseline Levels ◽  
Line Level ◽  
Pheromone Signalling ◽  
Repeat Visits ◽  
Pheromone Trail

Social insects often respond to signals and cues from nest-mates, and these responses may include changes in the information they, in turn, transmit. During foraging, Lasius niger deposits a pheromone trail to recruit nestmates, and ants that experience trail crowding deposit pheromone less often. Less studied, however, is the time taken for signalling to revert to baseline levels after conditions have returned to baseline levels. In this paper we study the behaviour of L. niger foragers on a trail in which crowding is simulated by using dummy ants — black glass beads coated in nestmate cuticular hydrocarbons. Ants were allowed to make four repeat visits to a feeder with dummy ants, and thus crowding, being present on the trail on all visits (CCCC), none (UUUU) or only the first two (CCUU). If dummy ants were always present (CCCC), pheromone deposition probability was low in the first two visits (54% of ants deposited pheromone) and remained low in visits 3 and 4 (51%). If dummy ants were never present (UUUU) pheromone deposition probability was high in the first two visits (93%) and remained high in visits 3 and 4 (83%). If dummy ants were present on the first two visits but removed on the second two visits (CCUU) pheromone deposition probability was low in the first two visits (61%) but rose in the second two visits (69%). This demonstrates that even after pheromone deposition has been down-regulated due to crowding in the first two visits, it is rapidly up-regulated when crowding is reduced, although it does not immediately return to the base line level.

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