Temperature dependence and bidirectional cation fluxes in red blood cells from spontaneously hypertensive rats.

Abstract

SUMMARY The net passive influx of Na + and efflux of K + (orthodirection) through the red blood cell membranes from spontaneously hypertensive rats (SHR) were observed to be significantly higher (p < 0.05) than those of three strains of normotensive rats when the measurements were made at 4°C. Similar comparative studies, carried out at 37°C, in the absence or presence of ouabain, showed no difference in these fluxes through this membrane from SHR compared to those from Wistar-Kyoto (VVKY) rats, one of the normotensive strains. A study was undertaken to determine the temperature at which the greater cation fluxes in SHR red blood cells occurred. The net fluxes of Na + and K + decreased as the temperature was reduced from 37° to 15°C, but a paradoxical increase in the fluxes was observed as the temperature was decreased from 15° to 4°C. Only with this temperature shift (15°t o 4°C) was the increase in flux significantly greater in SHR than in VVKY cells. Subsequent studies were designed to determine whether the difference in the transport systems of red blood cells of SHR and VVKY could be observed in fluxes of these cations in either direction across the membrane. For "reverse direction" flux studies, red blood cells were loaded with Na + (to 130 mEq/liter cell water) and depleted of K + (to 30 mEq/liter cell water) by incubation with the ionophore monensin. The reverse passive efflux of Na + and influx of K + at 4°C of cells from SHR were significantly greater than those of VVKY. Thus, the abnormality of the red blood cell membrane in SHR behaves as if it were just an increase in the size or number of pores through which Na + and K + diffuse freely at low temperatures. (Hypertension 6: 42-48, 1984)

Norepinephrine overflow in perfused mesenteric arteries of spontaneously hypertensive rats.

“…40 The /3-adrenergic agonist isoproterenol also produced a similar degree of enhancement of the field stimulation-induced release of [ The cause for this enhanced efflux of norepinephrine cannot be completely determined from the present experiments. However, several papers report that there is an increased sodium permeability in erythrocytes of SHR 41 - 43 and that fractional sodium excretion (percent of amount ingested) by SHR was significantly less during weeks 4-7 but did not differ appreciably between SHR and WKY control rats after 8 weeks of age. 44 Additionally, the increased ion turnover that has been reported in vascular tissue of SHR 45 -47 could result in a more labile calcium pool.…”

Is intracellular sodium increased in hypertension?

“…This may explain why in the majority of studies the K,/Na, ratio of erythrocytes is about 1O:l and that of leucocytes about 4:l. The influx of Na+ during cell preparation and the difference between the P,, of erythrocytes and leucocytes may also explain why increased leucocyte Na, in hypertension has been a more consistent finding than the increased Na, of erythrocytes. There is evidence for increased P,, of erythrocytes in hypertensive subjects and of erythrocytes, leucocytes and vascular smooth muscle cells in rats with spontaneous and DOCA-salt hypertension (34,44,56,58,64,(67)(68)(69).…”

Influence of Na+ disorder on cytoplasmic conductivity and cellular electromagnetic (EM) energy absorption of human erythrocytes (PONE-D-21-36089)

“…In parallel, the cell number was microscopically determined using a standard haemocytometer (Improved Neubauer, Marien Field, Lauda-Koenigshofen, Germany). After the haematocrit-centrifugation and cell number was obtained, mean cell volume (MCV) was determined following standard clinical methods [ 30 , 31 ]. No significant lysis of the cells was observed because the supernatant of the centrifuged cells in the haematocrit tube was clear.…”

“…The suspension was spun down at 10,000 g for 8 min. A 300 μl of the packed cell volume was then pipetted into a pre-weighed test tube [ 30 , 31 ]. In parallel, the haematocrit cell volume ( H ct ) was determined experimentally.…”