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

In vitro experiments were designed to assess the inhibitory effect of the thiazide diuretic methyclothiazide (MCTZ) on contractile responses to norepinephrine (NE) of mesenteric rings from hypertensive patients and normotensive controls. Arteries were taken from portions of mesocolon from 24 patients: 13 hypertensives and 11 normotensives. Changes in the tension of mesenteric ring preparations were measured isometrically. Histologic studies showed that the arteries from hypertensive patients exhibited 1) a greater media thickness-to-lumen diameter ratio, 2) a smaller lumen diameter, and 3) identical media cross-sectional area as those of normotensive controls. At the physiologic level, the hypertensive and normotensive arteries display similar contractile responses to KCl 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 associated with the remodeling of the human mesenteric artery and that MCTZ is as efficient in inhibiting the contractile response induced by NE on hypertensive than on normotensive arteries.