Morphology of resistance arteries and comparison of effects of vasoconstrictors in mild essential hypertensive patients.

We have compared the response of small subcutaneous resistance arteries from 15 mild essential hypertensive patients and 13 normotensive controls to various potentially pathophysiologically important vasoconstrictors. Blood vessels obtained from gluteal subcutaneous biopsies from hypertensive patients exhibited a significantly smaller external diameter and lumen and greater media/lumen ratio than those of normotensive subjects, but no significant difference in media thickness or cross-sectional area. Vasoconstrictor peptides produced varying effects on resistance arteries of hypertensive patients relative to controls: angiotensin II and arginine vasopressin elicited normal active media stress responses, while the contractile effect of endothelin-1 was depressed. Norepinephrine media stress responses were also blunted in hypertensive patients. Cocaine produced a shift to the left of the norepinephrine dose-response in vessels from both controls and hypertensive patients. Since the lumen diameter of blood vessels was reduced in hypertensive patients, vasoconstrictor responses were amplified, resulting in calculated pressor responses to endothelin-1 similar to those of normotensive controls. These results demonstrate the structural and functional alterations present in resistance arteries of mild essential hypertensive patients, which may be involved in maintaining elevated blood pressure.