Comparative nuclear magnetic resonance studies of water permeability of red blood cells from maternal venous blood and newborn umbilical cord blood

Changes observed in erythrocyte cells exposed to an alternating current

Background and aims

Appliance of electric pulses induces red blood cells (RBCs) membrane poration, membrane aminophospholipid perturbation and alteration of the normal flip-flop process, resulting in various shape changes of the RBCs. We studied morphological and water permeability changes of RBCs bombarded with electrons in an alternating current circuit.

Methods

We used three venous blood samples of 100 mL and an alternating current device. The harvested blood was divided into four experimental sets to be used for various exposure times: 0 hours (control RBCs), 0.5h, 3h and 6h (electric-stimulated RBCs).

Following the electric current each of the four sets were further divided into three samples: one for the assessment of the echinocytes/RBCs ratio, another for the electron microscopy study of ultrastructural changes induced by the alternating electrical current and a larger third one for determining water permeability of RCBs by ¹H-NMR spectroscopy and morphological measurements.

Results

There is a small but statistically significant effect of the RBC exposure to alternating electric current on cell diameters. Exposure to electric current is positively and strongly correlated with the percentage of echinocytes in a duration-dependent manner. There is a strong and statistically significant correlation between electric current exposure and permeability to water as measured by ¹H-NMR spectroscopy.

Conclusion

Following interactions between electric current and RBC membrane, certain modifications were observed in the erythrocyte structure. We attribute the increased cell size to a higher permeability to water and a decreased tonicity. This leads to the transformation of the RBCs into echinocytes.

Protective effects of stem bark of Harungana madgascariensis on the red blood cell membrane

Background

Anemia is a condition that has multiple origins. One such origin is the destruction of red blood cells’ (RBCs) membrane induced by free radicals. Treatment of anemia could therefore be enhanced by the use of free radicals’ scavengers potentially found in some medicinal plants. In this study, the protective effect of Harungana madagascariensis on the RBCs’ membrane physiology was investigated in vitro and in vivo.

Methods

In vitro hemolytic anemia was induced by incubation of fresh human RBCs with carbontetrachloride (CCl₄) in Olive oil (Oo). Relaxation times of protons excited at 20 MHz (Carr-Purcell-Meiboom-Gill pulse sequence) in the absence or presence of paramagnetic Mn²⁺ ions (T_2i for “extracellular” water and T_2a for “intracellular” water, respectively) were determined at several temperatures (25–37°C) via Nuclear Magnetic Resonance (NMR) on a Bruker Minispec spectrometer. Water exchange times (T_e) were consequently calculated using the Conlon-Outhred equation: 1/T_e = (1/T_2a) – (1/T_2i). Morphological characteristics (mean cell volume, V, and cell surface area, A) were determined by photonic microscopy and the RBCs’ diffusional water permeability (P_d) was calculated as P_d = (1/T_e)*(V_a/A), where V_a is the aqueous volume in the RBC and is about 0.7 of the cell volume (V). The activation energy of the diffusional process (E_a) for the respective temperature range was estimated using the Arrhenius modified equation k = A(T/T₀)ⁿ*e^-Ea/RT. Inhibition of the water diffusion induced by incubation with para-chloro-mercuribenzoic acid (PCMB) at 25, 30 and 37°C was calculated as I(%) = [(Pd control – Pd sample)/Pd control]*100.

To investigate the protective influence of the extract on the RBC membrane, inhibition of the water permeability was evaluated on membranes pre-incubated with the Harungana madagascariensis extract. Male rats were used in in vivo investigations. Malondialdehyde (MDA) and cholesterol in the RBC membrane were estimated by induction of lipid peroxidation while the antioxidant properties of catalase (CAT) and superoxide dismutase (SOD) on the membrane were evaluated in regard to their antioxidant properties on the membrane.

Results

T_2a significantly decreased at each temperature. Te results were higher in both RBCs and RBCs + extract groups incubated with PCMB compared to non-incubated controls, but differences were not statistically significant. A high percentage (73.81 ± 7.22) of RBCs pre-incubated with the extract presented the regular biconcave shape. Inhibition by PCMB of the RBCs’ membrane water permeability was increased at 30°C and decreased in the presence of extract (25°C and 37°C), while Ea decreased from 30.52 ± 1.3 KJ/mol to 25.49 ± 1.84 KJ/mol. Presence of the Harungana madagascariensis extract normalized the SOD and CAT activities as well as the MDA and membrane cholesterol concentrations altered by the CCl₄-induced oxidative stress.

Conclusion

Harungana madagascariensis could protect the RBCs’ membrane through its antioxidative properties.

Comparative studies of water permeability of red blood cells from humans and over 30 animal species: an overview of 20 years of collaboration with Philip Kuchel

NMR measurements of the diffusional permeability of the human adult red blood cell (RBC) membrane to water (P(d)) and of the activation energy (E(a,d)) of the process furnished values of P(d) ~ 4 × 10(-3) cm/s at 25 °C and ~6.1 × 10(-3) cm/s at 37 °C, and E(a,d) ~ 26 kJ/mol. Comparative NMR measurements for other species showed: (1) monotremes (echidna and platypus), chicken, little penguin, and saltwater crocodile have the lowest P(d) values; (2) sheep, cow, and elephant have P(d) values lower than human P(d) values; (3) cat, horse, alpaca, and camel have P(d) values close to those of humans; (4) guinea pig, dog, dingo, agile wallaby, red-necked wallaby, Eastern grey kangaroo, and red kangaroo have P(d) values higher than those of humans; (5) mouse, rat, rabbit, and "small and medium size" marsupials have the highest values of P(d) (>8.0 × 10(-3) cm/s at 25 °C and >10.0 × 10(-3) cm/s at 37 °C). There are peculiarities of E(a,d) values for the RBCs from different species. The maximum inhibition of diffusional permeability of RBCs induced by incubation with p-chloromercuribenzene sulfonate varied between 0% (for the chicken and little penguin) to ~50% (for human, mouse, cat, sheep, horse, camel, and Indian elephant), and ~60-75% (for rat, guinea pig, rabbit, dog, alpaca, and all marsupials). These results indicate that no water channel proteins (WCPs) or aquaporins are present in the membrane of RBCs from monotremes (echidna, platypus), chicken, little penguin and saltwater crocodile whereas WCPs from the membranes of RBCs from marsupials have peculiarities.

Water channel proteins (later called aquaporins) and relatives: past, present, and future

Water channels or water channel proteins (WCPs) are transmembrane proteins that have a specific three-dimensional structure with a pore that can be permeated by water molecules. WCPs are large families (over 450 members) that are present in all kingdoms of life. The first WCP was discovered in the human red blood cell (RBC) membrane in 1980s. In 1990s other WCPs were discovered in plants, microorganisms, various animals, and humans; and it became obvious that the WCPs belong to the superfamily of major intrinsic proteins (MIPs, over 800 members). WCPs include three subfamilies: (a) aquaporins (AQPs), which are water specific (or selective water channels); (b) aquaglyceroporins (and glycerol facilitators), which are permeable to water and/or other small molecules; and (c) "superaquaporins" or subcellular AQPs. WCPs (and MIPs) have several structural characteristics which were better understood after the atomic structure of some MIPs was deciphered. The structure-function relationships of MIPs expressed in microorganisms (bacteria, archaea, yeast, and protozoa), plants, and some multicellular animal species [nematodes, insects, fishes, amphibians, mammals (and humans)] are described. A synthetic overview on the WCPs from RBCs from various species is provided. The physiological roles of WCPs in kidney, gastrointestinal system, respiratory apparatus, central nervous system, eye, adipose tissue, skin are described, and some implications of WCPs in various diseases are briefly presented. References of detailed reviews on each topic are given. This is the first review providing in a condensed form an overview of the whole WCP field that became in the last 20 years a very hot area of research in biochemistry and molecular cell biology, with wide and increasing implications.

Diffusional water permeability (PDW) of adult and neonatal rabbit renal brush border membrane vesicles

We have shown that there is a maturational increase in osmotic water permeability (Pf) of rabbit renal brush border membrane vesicles (BBMV). The purpose of the present study was to further investigate the changes in proximal tubule water transport that occur during postnatal development. Diffusional water permeability (PDW) has not been measured directly in adult or neonatal BBMV. We validated the method described by Ye and Verkman (Simultaneous optical measurement of osmotic and diffusional water permeability in cells and liposomes. Biochemistry 28:824-829, 1989) to measure PDW in red cell ghosts and liposomes, to examine the maturational changes in PDW in BBMV. This method utilizes the sensitivity of 8-aminonaphtalene-1,3,6-trisulfonic acid (ANTS) fluorescence to the D2O-H2O content of the solvent. ANTS-loaded neonatal (11 days old) and adult BBMV were rapidly mixed with two volumes of isoosmotic D2O solution using a stopped-flow apparatus at 5 degrees -37 degrees C. PDW was lower in neonatal than adult BBMV at 5 degrees (3.77 +/- 0.34 vs. 5.35 +/- 0.43 mm/sec, respectively, p<0.05) and 20 degrees C (7.03 +/- 0.40 vs. 9.04 +/- 0.25 mm/sec, respectively, p<0.001), but was not different at 30 degrees and 37 degrees C. The activation energy (Ea) was higher in neonatal than in adult BBMV (9.29 +/- 0.56 kcal/mol vs. 6.46 +/- 0.56 kcal/mol, p<0.001). In adult BBMV, PDW was inhibited by 0.5 mM HgCl2 by 46.6 +/- 3.6%, while it was not affected in neonatal BBMV (p<0.001). The results indicate that PDW can be measured in rabbit renal BBMV. There are significant changes in water transport across the apical membrane during postnatal development, consistent with a maturational increase in channel-mediated water transport.