| Abstrakt: |
The purpose of this study was to examine the short- and long-term effects of the calcium channel blocker, barnidipine, on renal hemodynamics and urinary albumin excretion in spontaneously hypertensive rats with streptozotocin-induced diabetes. Diabetic and nondiabetic spontaneously hypertensive rats and nonhypertensive rats were treated with barnidipine or placebo (vehicle). In the short-term experiment, barnidipine was given as a single bolus injection (3 μg/kg); in the long-term experiment, barnidipine was administered orally (15 mg/kg per day) for 16 to 20 weeks. Renal hyperfiltration was observed in both hypertensive and nonhypertensive rats at 1 to 2 weeks after induction of diabetes, without changes in renal blood flow. Although short-term administration of barnidipine significantly decreased mean arterial pressure and renal vascular resistance, barnidipine did not affect renal blood flow or glomerular filtration rate in hypertensive, diabetic rats. At 16 to 20 weeks after induction of diabetes, renal hyperfiltration and increased urinary albumin excretion were still observed in hypertensive rats given placebo, compared to values for hypertensive nondiabetic rats given placebo. Long-term administration of barnidipine to hypertensive, diabetic rats suppressed the increase in both glomerular filtration rate and urinary albumin excretion, and reduced systolic blood pressure without any change in renal blood flow, renal vascular resistance, or filtration fraction. These results indicate that in hypertensive, diabetic rats short-term administration of barnidipine, despite reducing renal vascular resistance, is less effective than long-term administration in restoring normal renal filtration, although long-term administration may normalize renal filtration and reduce urinary albumin excretion. [ABSTRACT FROM AUTHOR] |
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