Some pharmacological and elastic characteristics of isolated subcutaneous small arteries from patients with essential hypertension

To investigate the elastic characteristics of the wall of isolated subcutaneous resistance arteries from patients with essential hypertension, the response of the vessels to endothelium-dependent and -independent vasodilators and the dependence on calcium.

Subcutaneous resistance arteries were isolated from 16 patients with never-treated essential hypertension and from 16 normotensive controls matched for age and sex. The vessels were mounted in a myograph for isometric force development. The passive elastic characteristics were determined and then the response to acetylcholine, nitroprusside, felodipine, caffeine and calcium (in the presence of noradrenaline and prazosin or yohimbine) were determined.

Young's elastic modulus as a function of wall stress was similar in the two groups of vessels. The relaxation of vessels from hypertensive and normotensive in response to acetylcholine, nitroprusside and felodipine was also similar. However, the response to caffeine was increased in vessels from the hypertensive patients, although the relationship between the dependence on the effect of calcium on the behaviour of arteries from hypertensives and controls was similar in the presence of prazosin and yohimbine.

The altered morphology of subcutaneous resistance arteries from hypertensives is not caused by a change in the elastic characteristics of the wall material. The data support our previous observation of abnormal calcium handling in vessels from hypertensives, although they do not support the hypothesis that a generalized abnormality in endothelium-dependent or endothelium-independent relaxation is of importance in essential hypertension.