The link among nitric oxide synthase activity, endothelial function, and aortic and ventricular hypertrophy in hypertension

Hiroshi Hayakawa, Leopoldo Raij

Research output: Contribution to journalArticle

161 Scopus citations

Abstract

The adaptive changes that occur in the left ventricle (LV) and vessels in response to hypertension, namely, muscle hypertrophy/hyperplasia, endothelial dysfunction, and extracellular matrix increase, do not depend solely on blood pressure elevation. These changes are in fact, maladaptive since they are forerunners of cardiac failure, stroke, and renal failure. Nitric oxide, an endogenous vasodilator and inhibitor of vascular smooth muscle cell growth, is synthesized in the endothelium by constitutive nitric oxide synthase (cNOS). We investigated the relationships among LV and aortic cNOS activity (conversion of [14C] L-arginine to [14C] L-citrulline), with LV hypertrophy (LV weight/body weight), and (2) aortic hypertrophy (aortic weight/length) in spontaneously hypertensive rats (SHR) and Dahl salt sensitive (DS) rats matched for blood pressure (219±12 versus 211±7 mm Hg, P=NS) and age. Compared with their normotensive counterparts, aortic cNOS activity was increased 106% in SHR but reduced by 73% in DS rats. The correlation between blood pressure and aortic cNOS activity was positive (r = .74, P<.01) in SHR and negative (r=-.82, P<.01) in DS rats. LV cNOS activity was increased 73% in SHR compared with normotensive Wistar-Kyoto rats (P<.01). On the other hand, LVcNOS activity was not increased in hypertensive DS rats compared with normotensive DS rats. In SHR, aortic hypertrophy did not increase significantly and LV hypertrophy increased only 15%, whereas in hypertensive DS rats the aorta and LV hypertrophied 36% and 88%, respectively (both P<.01). Moreover, in DS rats there was a negative correlation between cNOS activity and aortic hypertrophy (r=-70, P<.01). In DS rats, antihypertensive therapy consisting of an angiotensin-converting enzyme inhibitor, perindopril, and a diuretic, indapamide, normalized blood pressure, aortic cNOS activity, and LV hypertrophy and reduced aortic hypertrophy. Our studies imply that upregulation of vascular cNOS activity has a protective cardiovascular homeostatic role in hypertension. Clinically, the variable end-organ disease observed in individuals with similar severity of hypertension may be explained, at least in part, by genetically conditioned differences in vascular cNOS activity in response to hypertension.

Original languageEnglish (US)
Pages (from-to)235-241
Number of pages7
JournalHypertension
Volume29
Issue number1 II
DOIs
StatePublished - Jan 1997

Keywords

  • endothelium
  • hypertension
  • hypertrophy, left ventricular
  • muscle, smooth, vascular
  • nitric oxide synthase
  • rats, Dahl
  • rats, inbred, SHR

ASJC Scopus subject areas

  • Internal Medicine

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