Combined antihypertensive therapy plays a crucial role in achieving targeted blood pressure reductions and renoprotection. We therefore compared the antihypertensive and antiproteinuric effects of combined therapy with either a calcium channel blocker (CCB) plus an angiotensin II receptor blocker (ARB) or an angiotensin converting enzyme inhibitor (ACE-I) plus an ARB in patients with type 2 diabetes mellitus complicated by overt nephropathy and mild to moderate hypertension. After a 12-week dietary control period, diabetic patients with mildly to moderately impaired renal function were randomly assigned to either a CCB (amlodipine 5 mg once daily) or an ACE-I (temocapril 2 mg once daily) for 12 weeks (monotherapy period). Both groups then received add-on therapy with an ARB (candesartan 4 mg once daily) for an additional 12 weeks. During the monotherapy period, blood pressure was decreased equally well in both groups. Daily urinary protein excretion remained unchanged in the CCB-treated group (control period, 4.0 +/- 1.8 g/day vs. CCB period, 4.1 +/- 1.9 g/day; ns; n = 8), but decreased in the ACE-I-treated group (control period, 4.3 +/- 1.8 g/day vs. ACE-I period, 3.5 +/- 1.7 g/day; p < 0.05; n = 9). After the combined therapy period, blood pressure was decreased to the same degree in both groups. Although ARB plus CCB significantly reduced urinary protein excretion (to 3.5 +/- 1.5 g/day; p < 0.05 vs. control period; n = 8), a more profound reduction was achieved with ARB plus ACE-I (to 2.6 +/- 1.3 g/day; p < 0.01 vs. control period; n = 9). Monotherapy with the ACE-I increased the serum potassium concentration, and this elevation was sustained after addition of the ARB. In contrast, the serum potassium concentration was not influenced by monotherapy with the CCB, but was significantly increased after addition of the ARB. A decreased hematocrit was observed in the ARB plus ACE-I group. The present study suggests that combined antihypertensive therapy with either a CCB plus an ARB or an ACE-I plus an ARB exerts an antiproteinuric effect in patients with type 2 diabetic nephropathy with mildly impaired renal function. Although the latter combination had a more profound effect, it was associated with an increased serum potassium concentration and worsening of renal anemia. Thus, the combination of a CCB and an ARB should be the first line antihypertensive therapy in those with overt diabetic nephropathy. The long-term efficacy of these combined antihypertensive therapies will need to be further addressed in a future study.

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T-type calcium channel blockers have been previously shown to protect glomeruli from hypertension by regulating renal arteriolar tone. To examine whether blockade of these channels has a role in protection against tubulointerstitial damage, we used a stereo-selective T-type calcium channel blocker R(-)-efonidipine and studied its effect on the progression of this type of renal injury in spontaneously hypertensive rats that had undergone subtotal nephrectomy. Treatment with racemic efonidipine for 7 weeks significantly reduced systolic blood pressure and proteinuria. The R(-)-enantiomer, however, had no effect on blood pressure but significantly reduced proteinuria compared to vehicle-treated rats. Both agents blunted the increase in tubulointerstitial fibrosis, renal expression of alpha-smooth muscle actin and vimentin along with transforming growth factor-beta (TGF-beta)-induced renal Rho-kinase activity seen in the control group. Subtotal nephrectomy enhanced renal T-type calcium channel alpha1G subunit expression mimicked in angiotensin II-stimulated mesangial cells or TGF-beta-stimulated proximal tubular cells. Our study shows that T-type calcium channel blockade has renal protective actions that depend not only on hemodynamic effects but also pertain to Rho-kinase activity, tubulointerstitial fibrosis, and epithelial-mesenchymal transitions.

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Blood pressure (BP) measured at home early in the morning (HBP) has been recognized as a useful predictor for organ damage and has been viewed as an important therapeutic target in patients with hypertension. The present study was aimed to determine whether this notion holds true in patients with progressive renal disease.The study enrolled patients with mild to moderate renal impairment. They were all directed to record selfmeasured HBP to evaluate the adequacy of BP control. In addition to the conventional antihypertensive therapy, intensive treatment to more efficiently reduce elevated morning HBP was applied, especially in patients with diabetic nephropathy. The results were as follows:1) The status of BP control assessed using HBP and office/clinic BP (OBP) shows predominance of morning hypertension. The prevalence of patients with well-controlled systolic HBP was 38%, those with poorly-controlled HBP 30%, masked hypertension 20% and white coat hypertension 12%. 2) Early morning systolic HBP in diabetics was significantly higher than that in non-diabetics. However, when evaluated on systolic OBP, both groups were comparable. 3) Logistic regression analysis showed that the predictive variables to explain morning hypertension (more than 130 mmHg and increased systolic HBP) were age, amount of daily urinary protein excretion and left ventricular mass index (LVMI). 4) Following conventional therapy, intensive antihypertensive therapy consisting of calcium channel blockers (CCB) and/or diuretics given in the morning, and angiotensin receptor blockers (ARB) given in the evening, together with 1-blockers given at bedtime, efficaciously reduced elevated HBP in the morning. This result was associated with significant reduction in daily urinary protein excretion and in serum plasminogen-activator inhibitor (PAI-1) concentration. The present study indicates that, regardless of ongoing conventional antihypertensive therapy, the majority of patients with renal disease had morning hypertension, suggesting that these patients are at a higher risk for cardiovascular disease. For the purpose of improving morning hypertension, intensive treatments with combined CCB, ARB and 1-blockers could have substantial benefit on the morbidity and prognosis in patients with diabetic nephropathy. (Internal Medicine 44: 1239-1246, 2005)