Direct vascular actions of methyclothiazide in remodeled mesenteric arteries from hypertensive patients

In vitro experiments were designed to assess the inhibitory effect of the t hiazide diuretic methyclothiazide (MCTZ) on contractile responses to norepi nephrine (NE) of mesenteric rings from hypertensive patients and normotensi ve controls. Arteries were taken from portions of mesocolon from 24 patient s: 13 hypertensives and 11 normotensives. Changes in the tension of mesente ric ring preparations were measured isometrically. Histologic studies showe d that the arteries from hypertensive patients exhibited 1) a greater media thickness-to-lumen diameter ratio, 2) a smaller lumen diameter, and 3) ide ntical media cross-sectional area as those of normotensive controls. At the physiologic level, the hypertensive and normotensive arteries display simi lar contractile responses to KCI and NE. Furthermore, our results indicate that MCTZ induces concentration-dependent inhibition of the vasoconstrictor responses to NE. This study provides evidence that hypertension is associa ted with the remodeling of the human mesenteric artery and that MCTZ is as efficient in inhibiting the contractile response induced by NE on hypertens ive than on normotensive arteries. Am J Hypertens 2001;14:989-994 (C) 2001 American Journal of Hypertension, Ltd.