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Mechanisms of blood pressure regulation in hypertension studied by Laser based EMFA technique PowerPoint PPT Presentation


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FLI. Erythrocyte: force transducer. Mechanisms of blood pressure regulation in hypertension studied by Laser based EMFA technique. Shamci Monajembashi. Greulich Lab. Hemodynamic forces in vivo. Hypertension (high blood pressure): The endemic disease No.1 and a normal aging process.

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Mechanisms of blood pressure regulation in hypertension studied by Laser based EMFA technique

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Mechanisms of blood pressure regulation in hypertension studied by laser based emfa technique

FLI

Erythrocyte:

force transducer

Mechanisms of blood pressure regulation in hypertension studied by Laser based EMFA technique

Shamci Monajembashi

Greulich Lab

Hemodynamic forces in vivo

Hypertension (high blood pressure):

The endemic disease No.1 and a normal aging process

  • Shear stress due to blood flow

  • Hydrostatic pressure due to blood pressure

  • Cyclic stretch due to deformation of vessel wall

Endothelial nitric oxide (eNO) is produced in cells of the inner lining (intima) of blood vessels, diffuses to the smooth muscle cells (SMCs) of the media, where it causes relaxation of SMCs.

Substances acting on or prolonging this process are candidates for blood pressure relaxing drugs (for example VIAGRA).

So far, principally shear stress and cyclic stretch are used for studies on the response of cells to hemodynamic forces. However, little is reported about the response of endothelial cells to high vertical pressure in a few seconds.

The laser technique: Simulation of blood pressure by

EMFA (Erythrocyte Mediated Force Application)

Principle of EMFA

Fixed erythrocyte which is attached on the surface of endothelial cell, acts as a handle for optical tweezers to deform the cell.

HUVEC (Human Umbilical VeinEndothelial)Cells react by dramatic morphology changes after pressurizing

Laser power: 460 mW for 6 sec;Total observation time: 27 min.

Cell retraction changed after 6 min and lasted for 6 min (B-C).

Cell recovered after 18 min (D).

Laser power: 460 mW for 6 sec (B); Total observation time: 48 min.

Relaxation started ca. 6 min after EMFA pressure and lasted for ca. 41 min (C-F).

Stretch-activated ion channels are involved in the orienting response of endothelial cells (ECs) to pressure, e.g. pressure-induced morphological response of ECs is dependent on the external Ca++

Ca and NO correlate

Effect of calcium antagonists on endothelial nitric oxide bioavailibility

  • Perspectives

  • EMFA is the only experimental method which stimulates endothelial cells in true accordance to the blood pressure characteristics.

  • The combined mechanical and physiological response of endothelial cells to EMFA offers new possibilities in diagnosis and therapy of diseases based on endothelial dysfunctions.

  • Such simultaneously observations of two complex physiological phenomena after precise physical influence are so far in the aging research without comparison.

  • Technical help:

  • Gabi GĂĽnther, Silke Schulz

Calcium antagonists (CAs) are important drugs for the treatment of hypertension.

Amlodipine-stimulated NO release in HUVECs after EMFA:

A: typical changes of NO concentration after EMFA without Amlodipine,

B-C: prolonged NO release in present of Amlodipine after EMFA,

D: reduction of Amlodipine after 19 hours.


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