Use of erythrocyte membrane transport of sodium to assess clinical conditions associated with hypertension and lipid peroxidation

Jung Sook Kang, Purdue University

Abstract

Red blood cell sodium transport and platelet aggregation were used as tools to assess clinical conditions associated with nutrition status in two different studies. The research project of the first study addressed whether there is an interaction between sodium and calcium in the development of hypertension. To investigate this possible interaction, we examined the red blood cell sodium transport, platelet aggregability as well as blood pressure of Dahl salt sensitive rats fed either a sodium deficient diet or a sodium supplemented diet without calcium supplement or a calcium channel blocker, nitrendipine. A diet with moderately elevated sodium (2.6%) did not elevate blood pressure. Calcium supplement and nitrendipine had a hypotensive effect only when blood pressure was elevated with 8.0% sodium intake. Rats with nitrendipine had significantly (p $<$ 0.025) lower ouabain sensitive sodium efflux of red blood cells with significantly (p $<$ 0.001) higher cellular sodium than any other group. Rats fed a low sodium diet had significantly (p $<$ 0.01) lower platelet aggregability versus all other groups fed high sodium diets, especially lower in the initial phase of aggregation (p $<$ 0.001). The purpose of the second study was to test the feasibility of using cation transport across red blood cell membrane to determine the extent of membrane damage upon exposure to a free radical generating system, phenazine methosulfate (PMS) and to assess the effect of dietary vitamin E, selenium and polyunsaturated fatty acids on oxidative membrane damage. To accomplish this purpose, we measured the sodium leak of red blood cell, malondialdehyde production and platelet aggregability in rats fed diets modified with vitamin E, selenium, lard or corn oil. Selenium did not affect the passive sodium leak of untreated and PMS treated red blood cells. Red blood cells from vitamin E deficient rats were susceptible to hemolysis with low PMS (0.03mM) compared with 0.5 mM that was used to measure sodium leak for other groups. Passive sodium leak of untreated cells was significantly (p $<$ 0.05) higher in rats fed vitamin E deficient corn oil based diet than fed vitamin E sufficient diet. Platelet aggregation of selenium sufficient rats was significantly higher (p $<$ 0.01) than that of selenium free diet. No measurable malondialdehyde was produced in red blood cells or liver from rats on selenium test diets or vitamin E test diets.

Degree

Ph.D.

Advisors

Smith, Purdue University.

Subject Area

Nutrition|Anatomy & physiology|Animals

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