Cardiomyocyte volume-weighted nuclear volume and spironolactone therapy in spontaneously hypertensive rats

OBJECTIVE: To evaluate the blood pressure (BP) and cardiomyocyte nuclei hypertrophy of spontaneously hypertensive rats (SHR) treated with spironolactone and with spironolactone and an angiotensin-converting enzyme inhibitor and calcium channel blocker. STUDY DESIGN. Six groups with 5 SHR each were treated for 13 weeks: control group, spironolactone groups (5, 10 and 30 mg/kg/d, or low, moderate and high doses, respectively), and spironolactone and enalapril or/and verapamil. Blood pressure (BP) and cardiomyocyte volume-weighted nuclear volume (VWNV) were studied. RESULTS: The usual evolution of BP in young adult SHR was greatly altered by spironolactone treatment, with either attenuation or reversion of the BP tendency to increase. The treatments efficiently reduced the cardiomyocyte VWNV >45%. confirming efficient action of both spironolactone monotherapy at moderate and high dose and spironolactone combined with enalapril or verapamil. However, the high dose of spironolactone, and spironolactone plus enalapril or verapamil showed no significant differences in cardiomyocyte VWNV. Correlation between VWNV and BP (13th week) suggested that BP degree influences cardiomyocyte VWNV. CONCLUSION: The effect of spironolactone monotherapy seems to be dose dependent, and the combination with enalapril or verapamil improves spironolactone efficiency in BP reduction but not in prevention/attenuation of cardiac myocyte nuclear hypertrophy.