Effects of antihypertensive therapy on cardiac sodium/hydrogen ion exchanger activity and hypertrophy in spontaneously hypertensive rats

Bernardo V. Alvarez, Irene L. Ennis, María C. Camilión De Hurtado, Horacio E. Cingolani

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Sodium/hydrogen ion exchange is hyperactive in hypertension. Myocardial sodium/hydrogen ion exchange hyperactivity accompanies the regression of cardiac hypertrophy in spontaneously hypertensive rats (SHR) after long term control of blood pressure with enalapril. Objectives: To explore whether this effect is shared by other antihypertensive agents or is specific to angiotensin-converting enzyme inhibition. Animals and methods: SHR and normotensive Wistar Kyoto (WKY) rats were treated for five weeks with enalapril (20 mg/kg/day), nifedipine (10 mg/kg/day) or losartan (40 mg/kg/day). Sodium/hydrogen ion exchange activity was estimated in terms of both steady intracellular pH in HEPES buffer and the rate of intracellular pH recovery from intracellular acid loads in isolated superfused 2′-7′-bis(2-carboxyethyl)-5,-(and-6)-carboxyfluorescein, acetoxymethyl ester form-loaded papillary muscles. Results: Enalapril, nifedipine and losartan decreased systolic blood pressure in SHR to about the same value (140±3, 140±2 and 146±3 mmHg, respectively, at the end the treatment). However, the index of cardiac hypertrophy (heart weight to body weight ratio) was decreased to a smaller value with losartan than with nifedipine or enalapril (2.66±0.09, 3.06±0.05 and 2.86±0.04 mg/g respectively; P<0.05 ANOVA). For the untreated SHR, the index of cardiac hypertrophy was 3.30±0.04 mg/g. Myocardial sodium/hydrogen ion exchange hyperactivity in SHR was normalized by all treatments. Conclusions: The three treatments regressed cardiac hypertrophy and normalized sodium/hydrogen ion exchange exchange activity in SHR, and losartan was the most effective treatment for reversing cardiac hypertrophy, despite producing effects on blood pressure and sodium/hydrogen exchange activity similar to that of other antihypertensive drugs.

Original languageEnglish (US)
Pages (from-to)667-672
Number of pages6
JournalCanadian Journal of Cardiology
Volume18
Issue number6
StatePublished - Aug 29 2002

Keywords

  • ACE inhibitors
  • Calcium channel blockers
  • Hypertension
  • Hypertrophy

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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