Modulation of K-Cl cotransport in volume-clamped low-K sheep erythrocytes by pH, magnesium, and ATP

1996 ◽  
Vol 271 (4) ◽  
pp. C1049-C1058 ◽  
Author(s):  
O. Ortiz-Carranza ◽  
N. C. Adragna ◽  
P. K. Lauf
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Direct Effect ◽  
Volume Change ◽  
Blood Cells ◽  
Dual Roles ◽  
Maximal Inhibition ◽  
Volume Activation ◽  
Constant Cell ◽  
Low K

Cellular pH, ionized Mg (Mgi2+), and MgATP concentration of red blood cells, concomitantly with cell volume, change transiently during circulation. The action of these three effectors on Cl-dependent K efflux was examined in low-K sheep red blood cells with constant cell volume. Activation of K-Cl efflux by Mgi2+ extraction required ATP, suggesting that phosphorylation of a putative component occurred before Mgi2+ extraction. Conversely, Mg and ATP were synergistic inhibitors of K-Cl cotransport, since maximal inhibition was observed only in cells containing both ATP and > 300 microM Mgi2+. Both findings suggest dual roles for Mg and ATP. At 300-600 microM Mgi2+, lowering the pH from approximately 7.4 to approximately 6.5 stimulated K-Cl efflux only in fed cells, suggesting that protons oppose or release the inhibition by Mgi2+ and ATP. A direct effect of both protons and Mgi2+ on the cotransporter is suggested by their inhibition of K-Cl efflux in ATP-depleted cells. These findings are discussed in light of the current phosphorylation/dephosphorylation hypothesis.

Colloid osmotic pressure changes of dog's blood exposed to different mixtures of CO2 and air

1978 ◽  
Vol 44 (2) ◽  
pp. 254-257 ◽  
Author(s):  
Y. Kakiuchi ◽  
A. B. DuBois ◽  
D. Gorenberg
Keyword(s):  
Red Blood Cells ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Blood Cells ◽  
Freezing Point ◽  
Colloid Osmotic Pressure ◽  
Red Cell ◽  
Freezing Point Depression ◽  
Pressure Changes ◽  
Different Levels

Hansen's membrane manometer method for measuring plasma colloid osmotic pressure was used to obtain the osmolality changes of dogs breathing different levels of CO2. Osmotic pressure was converted to osmolality by calibration of the manometer with saline and plasma, using freezing point depression osmometry. The addition of 10 vol% of CO2 to tonometered blood caused about a 2.0 mosmol/kg H2O increase of osmolality, or 1.2% increase of red blood cell volume. The swelling of the red blood cells was probably due to osmosis caused by Cl- exchanged for the HCO3- which was produced rapidly by carbonic anhydrase present in the red blood cells. The change in colloid osmotic pressure accompanying a change in co2 tension was measured on blood obtained from dogs breathing different CO2 mixtures. It was approximately 0.14 mosmol/kg H2O per Torr Pco2. The corresponding change in red cell volume could not be calculated from this because water can exchange between the plasma and tissues.

scholarly journals Volume regulation by flounder red blood cells in anisotonic media

1977 ◽  
Vol 69 (5) ◽  
pp. 537-552 ◽  
Author(s):  
PM Cala
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Water Flow ◽  
Blood Cells ◽  
Volume Regulation ◽  
Control Cell ◽  
Regulatory Volume Decrease ◽  
Electrochemical Gradient ◽  
Osmotic Swelling ◽  
Inorganic Cation

The nucleated high K, low Na red blood cells of the winter flounder demonstrated a volume regulatory response subsequent to osmotic swelling or shrinkage. During volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation after osmotic swelling is referred to as regulatory volume decrease (RVD) and was characterized by net K and water loss. Since the electrochemical gradient for K is directed out of the cell there is no need to invoke active processes to explain RVD. When osmotically shrunken, the flounder erythrocyte demonstrated a regulatory volume increase (RVI) back toward control cell volume. The water movements characteristic of RVI were a consequence of net cellular NaCl and KCl uptake with Na accounting for 75 percent of the increase in intracellular cation content. Since the Na electrochemical gradient is directed into the cell, net Na uptake was the result of Na flux via dissipative pathways. The addition of 10(-4)M ouabain to suspensions of flounder erythrocytes was without effect upon net water movements during volume regulation. The presence of ouabain did however lead to a decreased ration of intracellular K:Na. Analysis of net Na and K fluxes in the presence and absence of ouabain led to the conclusion that Na and K fluxes via both conservative and dissipative pathways are increased in response to osmotic swelling or shrinkage. In addition, the Na and K flux rate through both pump and leak pathways decreased in a parallel fashion as cell volume was regulated. Taken as a whole, the Na and K movements through the flounder erythrocyte membrane demonstrated a functional dependence during volume regulation.

scholarly journals Impact of parity and gestational age of mothers with hypertension on birth weight, red blood cells and mode of delivery of their babies

1970 ◽  
Vol 19 (4) ◽  
pp. 3038-3044
Author(s):  
Helen Chioma Okoye ◽  
Chilota Chibuife Efobi ◽  
Josephat Maduabuchi Chinawa ◽  
Odutola Israel Odetunde ◽  
Awoere Tamunosiki Chinawa ◽  
...  
Keyword(s):  
Birth Weight ◽  
Red Blood Cells ◽  
Cell Volume ◽  
Gestational Age ◽  
Packed Cell Volume ◽  
Blood Cells ◽  
Mode Of Delivery ◽  
Poor Correlation ◽  
Hypertensive Group ◽  
The Impact

Background: Maternal factors are determinants of birth outcome which includes birth weight, haematological indices and mode of delivery of their babies.Objectives: To determine the impact of parity and gestational age of hypertensive mothers on some neonatal variables.Methods: A hospital based cross-sectional study of measurement of neonatal variables (birth weight, red blood cells and mode of delivery) among hypertensive mothers and their controls was conducted over a period of six months. Data were analyzed using the Statistical Package for Social Sciences program (SPSS), version 20.Results: There were statistically significant differences in means between the neonates of the hypertensive group and non-hypertensive group for maternal age (t =1.61, p = 0.002), baby weight (t =2.87, p < 0.001), haemoglobin (Hb) (t =4.65, p = 0.010) and packed cell volume (PCV) (t =4.75, p = 0.009), but none for gravidity (t =1.95, p = 0.927)For all subjects, there was poor correlation between gestational age and variables; birth weight , haemoglobin (Hb), packed cell volume (PCV), nucleated red blood cell (nRBC) and parity. Likewise, parity poorly correlated with variables; age, birth weight, Hb, PCV, and nRBC. There was a statistically significant association between mode of delivery and hypertension (χ2 =53.082, p <0.001) but none with having a family history of hypertension (χ2 =1.13, p = 0.287).Conclusion: Parity and gestational age of mothers with hypertension have no impact on birth weight and red cells when compared with their non-hypertensive counterparts. However, mothers of babies delivered by elective and emergency caesarean section were about 2-3 times more likely to be hypertensive than those that delivered through spontaneous vertex delivery.Keywords: Hypertension; neonate; gestational age; parity.

Urea alters set point volume for K-Cl cotransport, Na-H exchange, and Ca-Na exchange in dog red blood cells

1993 ◽  
Vol 265 (2) ◽  
pp. C447-C452 ◽  
Author(s):  
J. C. Parker
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Okadaic Acid ◽  
Blood Cells ◽  
Regulatory System ◽  
Set Point ◽  
Volume Sensor

Urea equilibrates rapidly across the red blood cells of mammals. It was speculated that urea might affect the cell volume sensor by virtue of its properties as a protein perturbant. At concentrations of 0.1-0.6 M, urea caused a decrease in the set points for shrinkage-induced Na-H exchange, swelling-induced K-Cl cotransport, and swelling-induced Ca-Na exchange of dog red blood cells. Okadaic acid opposed the action of urea on all three pathways. The effects were reversible and not due to cyanate. Formamide and acetamide had actions similar to urea but not as potent. Equimolar concentrations of methanol had no effect. The coordinated influence of urea on three separate volume-activated transporters suggests that it acts on a mutual regulatory system that senses and transduces volume stimuli.

Splenic red cell sequestration and blood volume measurements in conscious pigs

1985 ◽  
Vol 248 (3) ◽  
pp. R293-R301 ◽  
Author(s):  
J. P. Hannon ◽  
C. A. Bossone ◽  
W. G. Rodkey
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Blood Volume ◽  
Plasma Volume ◽  
Blood Cells ◽  
Physical Restraint ◽  
Red Cell ◽  
Red Cell Volume ◽  
Epinephrine Injection ◽  
Volume Measurements

When estimated by the dilution of 51Cr-labeled red blood cells under nearly basal conditions, immature splenectomized pigs (n = 20) had a circulating red cell volume of 17.8 +/- 1.64 (SD) ml/kg. At an assumed body-to-large vessel hematocrit (BH:LH) ratio of 0.9, plasma volume was 49.6 +/- 3.12 ml/kg and blood volume 67.3 +/- 3.67 ml/kg. Sham-operated pigs (n = 20) had a circulating red cell volume of 16.2 +/- 1.39 ml/kg, a plasma volume of 51.1 +/- 3.42 ml/kg, and blood volume of 67.2 +/- 4.12 ml/kg. Kinetic analysis of early 51Cr loss from the circulating blood of the sham-operated pigs indicated a splenic red cell sequestration of 4.5 +/- 0.89 ml/kg and a t1/2 of 9.76 +/- 1.93 min for splenic red cell turnover. Epinephrine injection (n = 6) and physical restraint (n = 8) caused rapid mobilization of splenic red blood cells in sham-operated pigs. Volume estimates in splenectomized pigs (n = 7) based on simultaneous dilutions of 51Cr-labeled red blood cells and 125I-labeled bovine albumin gave circulating red cell, plasma, and blood volumes of 18.4 +/- 2.46, 60.7 +/- 4.01, and 79.0 +/- 3.51 ml/kg, respectively, and a BH:LH ratio of 0.756 +/- 0.029. The latter value may have reflected an overestimation of plasma volume by the 125I-labeled albumin procedure.

Volume-dependent K+ transport in rabbit red blood cells comparison with oxygenated human SS cells

1989 ◽  
Vol 257 (1) ◽  
pp. C114-C121 ◽  
Author(s):  
N. al-Rohil ◽  
M. L. Jennings
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Cell Volume Regulation ◽  
Sulfhydryl Group ◽  
Cell Swelling ◽  
Inhibitory Potency ◽  
Ph Optimum ◽  
The Relationship ◽  
Low K ◽  
K Transport

In this study the volume-dependent or N-ethylmaleimide (NEM)-stimulated, ouabain-insensitive K+ influx and efflux were measured with the tracer 86Rb+ in rabbit red blood cells. The purpose of the work was to examine the rabbit as a potential model for cell volume regulation in human SS red blood cells and also to investigate the relationship between the NEM-reactive sulfhydryl group(s) and the signal by which cell swelling activates the transport. Ouabain-resistant K+ efflux and influx increase nearly threefold in cells swollen hypotonically by 15%. Pretreatment with 2 mM NEM stimulates efflux 5-fold and influx 10-fold (each measured in an isotonic medium). The ouabain-resistant K+ efflux was dependent on the major anion in the medium. The anion dependence of K+ efflux in swollen or NEM-stimulated cells was as follows: Br- greater than Cl- much greater than NO3- = acetate. The magnitudes of both the swelling- and the NEM-stimulated fluxes are much higher in young cells (density separated but excluding reticulocytes) than in older cells. Swelling- or NEM-stimulated K+ efflux in rabbit red blood cells was inhibited 50% by 1 mM furosemide, and the inhibitory potency of furosemide was enhanced by extracellular K+, as is known to be true for human AA and low-K+ sheep red blood cells. The swelling-stimulated flux in both rabbit and human SS cells has a pH optimum at approximately 7.4. We conclude that rabbit red blood cells are a good model for swelling-stimulated K+ transport in human SS cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of Na-Li exchange in high and low K sheep red blood cells

1989 ◽  
Vol 257 (1) ◽  
pp. C58-C64 ◽  
Author(s):  
K. H. Ryu ◽  
N. C. Adragna ◽  
P. K. Lauf
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Cell Types ◽  
Sheep Red Blood Cells ◽  
High K ◽  
Ping Pong ◽  
Order Of Magnitude ◽  
Low K ◽  
Kinetics Of ◽  
System Operating

The kinetic parameters and transport mechanism of Na-Li exchange were studied in both low K (LK) and high K (HK) sheep red blood cells with cellular Na [( Na]i) and Li concentrations [( Li]i) adjusted by the nystatin technique (Nature New Biol. 244: 47-49, 1973 and J. Physiol. Lond. 283: 177-196, 1978). Maximum velocities (Vm) for Li fluxes and half-activation constants (K1/2) for Li and Na of the Na-Li exchanger were determined. The K1/2 values for both Li and Na appeared to be similar in both cell types, although they were about two to three times lower on the inside than on the outside of the membrane. Furthermore, the K1/2 values for Li were at least an order of magnitude smaller than those for Na, suggesting substantial affinity differences for these two cations. The Vm values for Li fluxes, on the other hand, appear to be lower in HK than in LK cells. When Na and Li fluxes were measured simultaneously, a trans stimulatory effect by Na on Li fluxes was observed. From measurements of Li influx at different concentrations of external Li and different [Na]i, the ratio of the apparent Vm to the apparent external Li affinity was calculated to be independent of [Na]i for both types of sheep red blood cells. Similar trans effects of external Na were observed on Li efflux at varying [Li]i. These results are expected for a system operating by a “ping-pong” mechanism.

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