Objective: The present study was designed to investigate the effect of nicardipine administration upon systolic blood pressure (SBP) and cardiac hypertrophy in spontaneously hypertensive rats (SHR).
Design: SBP, heart: and left ventricle: body weight ratios, the cross-sectional area of cardiocytes, and the ultrastructure of the left ventricle were evaluated.
Methods: Ten-week old male SHR and age-matched normotensive Wistar-Kyoto rats were studied for 12 weeks. One group of SHR was treated for 12 weeks with a daily oral dose of 1 mg/kg nicardipine and another group with 1 mg/kg hydralazine; Wistar-Kyoto rats were used as a normotensive control group. Light and electron microscope techniques associated with image analysis and morphometry were used.
Results: Nicardipine administration normalized SBP values and significantly reduced the heart: and left ventricle: body weight ratios. Moreover, administration reduced the cross-sectional area of cardiocytes by approximately 38% in subendocardium and by 24% in subepicardium. Hydralazine administration significantly reduced SBP values but had no effect upon heart: or left ventricle: body weight ratios or the cross-sectional area of cardiocytes. Electron microscopy showed that nicardipine treatment was able to reduce the hypertension-dependent changes in cardiac ultrastructure consisting of alternations to intercalated discs and line Z morphology as well as in the decrease of the mitochondria: myofibrils ratio.
Conclusions: The above data indicate that nicardipine administration is able to reduce SBP and to counter the development of structural and ultrastructural changes in cardiac morphology which represent a common complication of arterial hypertension.