Entrapping of the spin label tempocholine into human erythrocytes by resealing after hyposmolar stress. Comparison with haemolysis. The effects of some membrane-active substances | JoVE Visualize

Entrapping of the spin label tempocholine into human erythrocytes by resealing after hyposmolar stress. Comparison with haemolysis. The effects of some membrane-active substances

C Lagercrantz, T Larsson, L Tollsten

Biochemical Pharmacology|January 1, 1985

View abstract on PubMed

Summary

Certain drugs, including chlorpromazine, hinder erythrocyte resealing after osmotic stress by affecting membrane pore closure. This impacts the entrapment of tempocholine, a spin label used to measure membrane integrity.

Area of Science:

Cell Biology
Biophysics
Pharmacology

Background:

Human erythrocytes (red blood cells) are susceptible to osmotic stress, leading to membrane pore formation and potential lysis.
The resealing process of erythrocyte membranes after osmotic stress is crucial for maintaining cell integrity.
Spin labels like tempocholine can be used to probe membrane permeability and resealing dynamics.

Purpose of the Study:

To investigate the effect of hyposmolar stress on human erythrocyte membranes using the spin label tempocholine.
To evaluate the influence of specific drug substances on the resealing process of erythrocyte membranes.
To explore the potential mechanism of drug action on membrane repair, possibly involving the calmodulin system.

Main Methods:

Erythrocytes were exposed to hyposmolar stress in solutions containing tempocholine.
Ascorbic acid was used to quench external tempocholine, allowing measurement of entrapped spin label via electron spin resonance (ESR).
The amount of entrapped tempocholine was quantified against varying osmolarities and in the presence of different drug substances.

Main Results:

Hyposmolar stress induced temporary pores in erythrocyte membranes, allowing tempocholine entrapment upon resealing.
Several drugs (chlorpromazine, trifluoperazine, nicardipine, amperozide, haloperidol) dose-dependently reduced tempocholine entrapment, indicating impaired resealing.
Calcium and magnesium ion depletion enhanced chlorpromazine's effect, and its action mirrored protective effects against hemolysis.

Conclusions:

The tempocholine entrapment method effectively measures erythrocyte membrane resealing after osmotic stress.
Investigated drug substances interfere with the erythrocyte membrane resealing process, particularly at low osmolarities.
The observed drug effects suggest a mechanism involving interaction with the calmodulin system during membrane repair.