STRUCTURE AND FUNCTION OF RESISTANCE ARTERIES OF HYPERTENSIVE PATIENTS TREATED WITH A BETA-BLOCKER OR A CALCIUM-CHANNEL ANTAGONIST

Objective To investigate the effects on resistance artery structure an d function of monotherapy with the beta-blocker atenolol or the calciu m channel antagonist nifedipine in its once a day form or gastrointest inal therapeutic system (GITS). Subjects Twenty well-controlled essent ial hypertensive patients matched for age, body mass index, duration a nd severity of hypertension. Normotensive subjects and untreated hyper tensives served as the reference groups. Methods Resistance-size small arteries (standardized lumen diameter 247 +/- 8 mu m) were dissected from a gluteal subcutaneous biopsy, and studied both on a wire myograp h and as pressurized vessels. Results The media width:lumen diameter r atio of arteries was 5.37 +/- 0.09% in normotensive subjects, 5.38 +/- 0.18% in patients treated with nifedipine GITS, 6.81 +/- 0.18% in pat ients treated with atenolol and 7.08 +/- 0.12% in untreated hypertensi ves (for each of the latter two groups P<0.001, versus each of the two former groups). The media stress developed in response to noradrenali ne and the endothelium-dependent relaxation induced by acetylcholine w ere significantly smaller in small arteries from untreated or atenolol -treated patients than they were in those from normotensive subjects o r nifedipine GITS-treated patients. Conclusion Hypertensive patients w ith well-controlled blood pressures under treatment for more than 1 ye ar with the once-a-day calcium channel antagonist nifedipine GITS exhi bit normal structure and function of gluteal subcutaneous small arteri es, whereas similar patients with blood pressure equally well controll ed by the P-blocker atenolol present thicker small arteries with abnor mal endothelium-dependent relaxation and altered contractility. Whethe r this finding applies also to other vascular beds, and whether it is associated with a better outcome in relation to morbidity and mortalit y resulting from elevated blood pressure, remain to be established.