scholarly journals Osmolar Concentration and Fixation of Mycoplasmas

1972 ◽  
Vol 110 (3) ◽  
pp. 1154-1162 ◽  
Author(s):  
Ruth M. Lemcke
Keyword(s):  
Osmolar Concentration

scholarly journals ION-INDUCED ULTRASTRUCTURAL TRANSFORMATIONS IN ISOLATED MITOCHONDRIA

1969 ◽  
Vol 42 (1) ◽  
pp. 221-234 ◽  
Author(s):  
Charles R. Hackenbrock ◽  
Arnold I. Caplan
Keyword(s):  
Marked Decrease ◽  
Active Form ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Dense Matrix ◽  
Low Levels ◽  
Osmolar Concentration ◽  
Oriented Membranes ◽  
Ultrastructural Transformation ◽  
Distinct Membrane

The energized uptake of low levels of Ca2+ in the presence and absence of phosphate by isolated rat liver mitochondria, and the perturbation effected by this activity on ultrastructural and metabolic parameters of mitochondria have been investigated. In the presence of phosphate, low levels of Ca2+ are taken up by mitochondria and result in various degrees of ultrastructural expansion of the inner mitochondrial compartment. This indicates that low levels of Ca2+ in the presence of phosphate, are accumulated in an osmotically active form into the water phase of the inner compartment. The first clearly observable quantitative increase in the volume of the inner compartment occurs after the accumulation of 100 nmoles Ca2+/mg protein. An accumulation of 150–200 nmoles Ca2+/mg protein, which is equivalent to the osmolar concentration of endogenous K+, is required to effect a doubling of the volume of the inner compartment. This degree of osmotic perturbation occurs as mitochondria transform from a condensed to an orthodox conformation. The osmotically induced orthodox conformation differs from the mechanochemically induced orthodox conformation previously described, in that its development is concomitant with a marked decrease in acceptor control and oxidative phosphorylation efficiency and it fails to transform to a condensed conformation in response to addition of ADP. In the absence of added phosphate, a maximum of 190 nmoles Ca2+/mg protein was found to be taken up by mitochondria (state 6). Ca2+ is apparently bound under state 6 conditions since the uptake does not effect an ultrastructural expansion of the inner compartment. Phosphate added after state 6 Ca2+ binding, however, results in an immediate ultrastructural expansion of the inner compartment. The addition of phosphate to mitochondria in the absence of exogenous Ca2- fails to effect an osmotic ultrastructural transformation. Under state 6 conditions, the binding of between 40 and 190 nmoles Ca2+/mg protein results in the formation of dense matrix inclusions which appear to be composed of tightly packed, concentrically oriented membranes. Under conditions in which the bound Ca2+ is subsequently released, there is a concomitant loss in the density of these matrix inclusions, leaving behind morphologically distinct membrane whorls in the mitochondrial matrix.

Mechanism of diuresis during negative pressure breathing

1959 ◽  
Vol 14 (1) ◽  
pp. 116-120 ◽  
Author(s):  
John W. Boylan ◽  
Dorothy E. Antkowiak
Keyword(s):  
Negative Pressure ◽  
Hormone Secretion ◽  
Free Water ◽  
Effective Mechanism ◽  
Water Diuresis ◽  
Antidiuretic Hormone Secretion ◽  
Clearance Studies ◽  
Negative Pressure Breathing ◽  
Solute Excretion ◽  
Osmolar Concentration

The diuresis associated with negative pressure breathing in moderately hydrated man is found to be due chiefly to an increase in the excretion of free water; solute excretion rises slightly and consistently. Simultaneous clearance studies do not reveal a characteristic pattern in renal hemodynamics for diuresis is observed to attend an increase, decrease or absence of change in RPF and GFR. There is, moreover, no effect on the peripheral venous hematocrit nor on the osmolar concentration of the plasma. Negative pressure breathing is without effect on urine flow when performed during maximal water diuresis or during the antidiuresis produced by infused Pitressin. These observations are in accord with the theory that the effective mechanism for the diuresis of negative pressure breathing is a reflex inhibition of antidiuretic hormone secretion. Submitted on September 19, 1958

URINARY OSMOLAR CONCENTRATION

1960 ◽  
Vol 239 (2) ◽  
pp. 144-147 ◽  
Author(s):  
Antonio C. deLeon ◽  
Leonard S. Dreifus ◽  
Samuel Bellet
Keyword(s):  
Osmolar Concentration

scholarly journals Concentrating ability of the kidneys in proteinuric patients

2002 ◽  
Vol 55 (3-4) ◽  
pp. 129-134 ◽  
Author(s):  
Dejan Petrovic ◽  
Radmila Obrenovic ◽  
Mileta Poskurica ◽  
Biljana Stojimirovic
Keyword(s):  
Creatinine Clearance ◽  
Concentration Index ◽  
Free Water ◽  
Urine Osmolality ◽  
Free Water Clearance ◽  
Urea Excretion ◽  
The Third ◽  
Endogenous Creatinine Clearance ◽  
Glomerular Proteinuria ◽  
Osmolar Concentration

Proteinuria causes damage to renal tubulointerstitium. The study included 50 patients (24 males and 26 females), mean age 46.50?13.08 years, with average endogenous creatinine clearance 87.29?31.17 ml/min. Regarding level of glomerular proteinuria patients were divided into three groups. The first group, with proteinuria less than 0.3 g/24h, included 19 patients (7 male and 12 female), average age 45.12?13.28 years and mean clearance of endogenous creatinine 94.27?34.70 ml/min. The second group, with proteinuria between 0.3 and 3.0 g/24h, comprised 18 patients (8 male and 10 female), mean age 45.39?12.64 years, and with mean clearance of endogenous creatinine 90.07?31.89 ml/min. The third group consisted of 13 patients (9 male and 4 female) with proteinuria values higher than 3,0 g/24h, average age 50.08?13.73 years and mean endogenous creatinine clearance 73.25?20.44 ml/min. In order to assess the concentrating ability of the kidneys we investigated: urine osmolality, osmolar concentration index, fractional osmolar excretion, fractional urea excretion and free water clearance. Results were statistically analyzed using Student, Mann-Whitney U test and (? test. Proteinuria leads to deterioration of concentrating ability of the kidneys.

Drinking and vasopressin release during ventricular infusions of hypertonic solutions

1980 ◽  
Vol 238 (5) ◽  
pp. R340-R345
Author(s):  
T. N. Thrasher ◽  
R. G. Jones ◽  
L. C. Keil ◽  
C. J. Brown ◽  
D. J. Ramsay
Keyword(s):  
Cerebrospinal Fluid ◽  
Statistical Difference ◽  
Vasopressin Release ◽  
Plasma Vasopressin ◽  
Hypertonic Solutions ◽  
Artificial Cerebrospinal Fluid ◽  
Osmolar Concentration

Six dogs were administered third ventricular infusions of artificial cerebrospinal fluid (CSF) (292 mosmol/l) alone or artificial CSF to which neither NaCl, sucrose, glucose, or urea was added to yield a final osmolar concentration of 500 mosmol/l. The volume of water drunk during 45 min of infusion was measured and blood was sampled for determination of plasma vasopressin concentration at 15-min intervals. Artificial CSF made hypertonic by addition of NaCl or sucrose stimulated water intakes of 9.0 +/- 3.2 ml/kg (mean +/- SE) and 7.3 +/- 3.7 ml/kg, respectively. There was no statistical difference in the amounts drunk and the latencies. In contrast, artificial CSF containing glucose, urea, or artificial CSF alone were without effect. Plasma vasopressin concentration increased significantly in response to intraventricular NaCl and sucrose but was not affected by glucose, urea, or artificial CSF alone. These data are compatible with an osmoreceptor mechanism mediating drinking and vasopressin release.

Influence of osmolarity of perfusate on contractility of mammalian myocardium

1963 ◽  
Vol 204 (6) ◽  
pp. 957-962 ◽  
Author(s):  
Jan Koch-Weser
Keyword(s):  
Time Course ◽  
Muscle Tension ◽  
Water Concentration ◽  
Myocardial Contraction ◽  
Papillary Muscles ◽  
Tension Development ◽  
Mammalian Myocardium ◽  
Spontaneous Contractions ◽  
External Stimuli ◽  
Osmolar Concentration

The effect of changes in the osmolarity of the perfusing fluid on strength and time course of myocardial contraction was studied in cat papillary muscles and atrial strips. Osmolar concentration was varied by adding up to 750 mm sucrose or mannitol to a slightly hypoosmolar solution, leaving molar concentrations of the original solutes unchanged. Optimum osmolarity for tension development by papillary muscles was close to that of serum (330 mosmol/ liter), but for atrial muscles was 150 mosmol/liter higher. Osmolarity changes apparently influence contractility by altering the intracellular water concentration. Increases of osmolarity up to the optimum augment tension development by increasing the degree of activation of the contractile elements. This may be due to increased concentration of calcium in a superficial area of the fiber. Increases of osmolar concentration above the optimum lower developed tension, probably by reducing the intrinsic speed of the muscle. Tension development in response to external stimuli is abolished by raising osmolarity to three times that of serum (1 osmol/liter). Spontaneous contractions cease in solutions of twice normal osmolar concentration.

scholarly journals Osmotic Conditions During the Embryonic and Early Larval Life of the Brook Lamprey (Lampetra Planeri)

1957 ◽  
Vol 34 (2) ◽  
pp. 237-252
Author(s):  
M. W. HARDISTY
Keyword(s):  
Water Content ◽  
Tap Water ◽  
Initial Permeability ◽  
Distilled Water ◽  
Continuous Increase ◽  
Outer Membranes ◽  
Lampetra Planeri ◽  
Short Time ◽  
Osmolar Concentration ◽  
Whole Egg

1. Observations have been made on the swelling of eggs in tap and distilled water. The rate of uptake of water through the outer membranes and the surface of the ovum fell off sharply within a short time of contact with water. In distilled water uptake into the perivitelline space was very much greater than in tap water, but there were no significant differences in the volume of the ovum itself in these two media. 2. The initial permeability of the ovum to water has been estimated as 0.049 µ3/µ2atm./min., falling after about 7 hr. to 0.003 and remaining at this level for the first 5 days of development. 3. The outer egg membranes are apparently freely permeable to water and ions, and the mean Cl concentration of the perivitelline fluid in the later stages of development was found to be only 2.4 mM/l. 4. Evidence is presented which points to a decrease in the volume of the embryo at some point between gastrulation and hatching. In tap water a contraction of the whole egg was observed from the fifth day onwards. 5. The water content of the embryo at hatching was not very much greater than that of the ovarian egg. After hatching, until the absorption of the yolk, there was a continuous increase in the fresh weight and water content of the ammocoetes. 6. The evidence suggests that the ovarian egg is in osmotic equilibrium with the peritoneal fluid (mean 110 mM/NaCl/l.). During development the osmolar concentration of the total egg fluid was reduced to values similar to those calculated from the known dilution, i.e. 30-40 mM/l. At hatching, the osmolar concentration of the embryo (80 mM/l.) was raised within a few days to 11-120 mM/l. 7. The observed reduction in Cl concentration of the whole egg was much greater than that calculated from the increases in volume. The Cl concentration of the embryo itself was reduced from an initial value of 56 to 15 mM/l. embryo fluid a week before hatching. 8. Determinations of the total Cl content of whole eggs and embryos showed a very marked loss of Cl ions in the two days following fertilization. Within 35 days after hatching the Cl level had been raised by active uptake to about four times the values at the time of hatching.

scholarly journals Some Aspects of Osmotic Regulation in Lampreys

1956 ◽  
Vol 33 (2) ◽  
pp. 431-447 ◽  
Author(s):  
M. W. HARDISTY
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Sea Water ◽  
Tap Water ◽  
Total Concentration ◽  
The Body ◽  
Unit Body Weight ◽  
Lampetra Planeri ◽  
The Mean ◽  
Osmolar Concentration

1. The mean osmolar concentration (expressed as mM. NaCl/1.) of the serum for Lampetra planeri was found to be 110 mM. in the ammocoete and 113 mM. in the adult. For adult L. fluviatilis serum in November the mean osmolar concentration was 143 mM. and in March 136 mM. 2. In adult planeri the Cl concentration of the body fluids accounted for nearly 90% of the total concentration as compared with only 58% in the serum of the ammocoete. Adult fluviatilis kept in tap water throughout the winter appeared to show an increase in Cl levels. 3. Evidence has been produced to support the view that the differences observed in water, fat and Cl content of ammocoete and adult planeri and adult fluviatilis are consequences of the period of starvation preceding sexual maturity. 4. Pronounced seasonal variations have been found in the fat and Cl content of ammocoetes of planeri. 5. The osmotic uptake of water has been determined for adults of both species in fresh water. In planeri the rate of uptake for unit body weight is about four times as great as in fluviatilis. 6. Observations have also been made on the osmotic loss of water of ammocoete and adult planeri and of adult fluviatilis in sea water of different concentrations. For unit body weight osmotic loss of water in planeri is about twice that of fluviatilis. 7. Total losses of Cl have been determined for ammocoete and adult planeri in distilled water and their effects on internal Cl levels have been studied. Observations have also been made on the active uptake of Cl. 8. Acclimatization experiments on ammocoetes and adult planeri and on adult fluviatilis have failed to produce any evidence of regulation in sea water.

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