SOME PHARMACOLOGICAL AND ELASTIC CHARACTERISTICS OF ISOLATED SUBCUTANEOUS SMALL ARTERIES FROM PATIENTS WITH ESSENTIAL-HYPERTENSION

Objective To investigate the elastic characteristics of the wall of is olated subcutaneous resistance arteries from patients with essential h ypertension, the response of the vessels to endothelium-dependent and -independent vasodilators and the dependence on calcium. Methods Subcu taneous resistance arteries were isolated from 16 patients with never- treated essential hypertension and from 16 normotensive controls match ed for age and sex. The vessels were mounted in a myograph for isometr ic force development The passive elastic characteristics were determin ed and then the response to acetylcholine, nitroprusside, felodipine, caffeine and calcium (in the presence of noradrenaline and prazosin or yohimbine) were determined. Results Young's elastic modulus as a func tion of wall stress was similar in the two groups of vessels. The rela xation of vessels from hypertensive and normotensive in response to ac etylcholine, nitroprusside and felodipine was also similar. However, t he response to caffeine was increased in vessels from the hypertensive patients, although the relationship between the dependence on the eff ect of calcium on the behaviour of arteries from hypertensives and con trols was similar in the presence of prazosin and yohimbine. Conclusio ns The altered morphology of subcutaneous resistance arteries from hyp ertensives is not caused by a change in the elastic characteristics of the wall material. The data support our previous observation of abnor mal calcium handling in vessels from hypertensives, although they do n ot support the hypothesis that a generalized abnormality in endotheliu m-dependent or endothelium-independent relaxation is of importance in essential hypertension.