Altered membrane microviscosity in essential hypertension: relationship with family history of hypertension and sodium-lithium countertransport activity.

Abstract

OBJECTIVE:

To investigate the alterations in erythrocyte ghost membrane microviscosity in essential hypertensive patients and to determine the relationship between these changes and the sodium-lithium countertransport activity as a sensitive marker of membrane function.

SUBJECTS:

Forty-three normolipidaemic essential hypertensive patients (23 treated, 20 untreated) and 27 normotensive controls were studied. Patients were attending the hospital hypertension clinic or a local general practitioner's surgery.

METHODS:

Erythrocyte sodium-lithium countertransport activity was measured. The Michaelis constant (Km) for extracellular sodium and maximal reaction velocity for sodium-lithium countertransport were measured in a subgroup consisting of 22 essential hypertensive patients and 11 normotensive controls. Erythrocyte membrane microviscosity was measured using fluorescence polarization anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-trimethylammoniumphenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH).

RESULTS:

There was no significant difference in the fluorescence polarization anisotropy of DPH or TMA-DPH between normotensive and essential hypertensive patients. However, the fluorescence polarization anisotropy of TMA-DPH was increased significantly (reflecting increased membrane microviscosity) in hypertensive patients with a family history of hypertension compared with in patients without a family history of hypertension. The standard sodium-lithium countertransport activity was elevated in essential hypertensive patients compared with normotensive controls, and the Km for sodium was significantly lower in patients with a family history of hypertension than in patients without a family history of hypertension. Patients with a family history of hypertension were clustered, with significantly lower Km for sodium and higher TMA-DPH anisotropies than either hypertensive patients without a family history of hypertension or normotensive controls.

CONCLUSIONS:

These findings suggest that a high membrane microviscosity affecting the outer region of the lipid bilayer is associated with altered sodium-lithium countertransport kinetics in a subgroup of essential hypertensive patients consisting of those with a family history of hypertension.

• Authors: S J Carr, K Sikand, D Moore, R I Norman
• Journal: Journal of hypertension (J Hypertens) Vol. 13 Issue 1 Pg. 139-46 (Jan 1995) ISSN: 0263-6352 [Print] England
• PMID: 7759844 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antiporters
• Lipid Bilayers
• sodium-lithium countertransporter
• Lithium
• Sodium

Topics

• Antiporters (metabolism)
• Erythrocyte Membrane (metabolism, physiology)
• Female
• Fluorescence Polarization
• Humans
• Hypertension (blood, drug therapy, genetics)
• Lipid Bilayers (metabolism)
• Lithium (metabolism)
• Male
• Middle Aged
• Pedigree
• Sodium (metabolism)
• Viscosity