Vascular reactivity of arteria femoralis in adult and aged spontaneously hypertensive and Wistar-Kyoto rats.

AIM

The relationship of age and hypertension on endothelial dysfunction and increased responses to vasoconstrictor stimuli.

BACKGROUND

Hypertension is a disease accompanied by endothelial dysfunction and is characterized by an impaired vascular reactivity and enhanced activity of sympathetic nervous system.

MATERIALS AND METHODS

In our experiment, we used spontaneously hypertensive rats representing model of essential hypertension and the Wistar-Kyoto rats as normotensive strain. Femoral arteries of adult and aged rats were put into the chamber of Mulvany-Halpern isometric myograph. As the nutrient solution, the modified Krebs-Henseleit solution having temperature 37 °C and bubbled with O2 was used. After 30 minutes stabilization of blood vessels, a dose-dependent curve of norepinephrine response was recorded (concentrations 3x10-8 M, 10-7 M, 3x10-7 M, 10-6 M, 3x10-6 M, 10-5 M, 3x10-5 M, 10-4 M), followed by a dose-dependent curve of acetylcholine response (concentrations 3x10-8 M, 10-7 M, 3x10-7 M, 10-6 M, 3x10-6 M).

RESULTS

Our experiments recorded an increased reactivity to contraction stimuli in spontaneously hypertensive animals. Vascular reactivity to norepinephrine at 5 month and 12 month old rats from the same group was not significantly affected. Our experiments on the other hand, did not record a reduced endothelium-dependent relaxation in hypertensive compared to normotensive animals, neither in different age groups.

CONCLUSIONS

Increased norepinephrine-induced contraction occurs even before development of reduced acetylcholine-induced relaxation in SHR rats. We predict that in our experiment hypertension plays a bigger role in the development of endothelial dysfunction than aging (Fig. 2, Ref. 22).