Influence of T-calcium channel blocker treatment on deterioration of renal function in chronic kidney disease

New Insights into the Nephroprotective Potential of Lercanidipine

Kidneys are responsible for many crucial biological processes in the human body, including maintaining the water-electrolyte balance, pH, and blood pressure (BP), along with the elimination of toxins. Despite this, chronic kidney disease (CKD), which affects more and more people, is a disease that develops insidiously without causing any symptoms at first. The main purpose of this article is to summarize the existing literature on lercanidipine, with a particular focus on its nephroprotective properties. Lercanidipine is a third-generation dihydropyridine (DHP) blocker of calcium channels, and as such it possesses unique qualities such as high lipophilicity and high vascular selectivity. Furthermore, it acts by reversibly inhibiting L-type and T-type calcium channels responsible for exerting positive renal effects. It has been shown to reduce tissue inflammation and tubulointerstitial fibrosis, contributing to a decrease in proteinuria. Moreover, it exhibited antioxidative effects and increased expression of molecules responsible for repairing damaged tissues. It also decreased cell proliferation, preventing thickening of the vascular lumen. This article summarizes studies simultaneously comparing the effect of lercanidipine with other antihypertensive drugs. There is still a lack of studies on the medications used in patients with CKD, and an even greater lack of studies on those used in patients with concomitant hypertension. Therefore, further studies on lercanidipine and its potential in hypertensive patients with coexisting CKD are required.

Questioning the renoprotective role of L-type calcium channel blockers in chronic kidney disease using physiological modeling

Chronic kidney disease (CKD) is characterized by the progressive functional loss of nephrons and hypertension (HTN). Some antihypertensive regimens attenuate the progression of CKD (blockers of the renin-angiotensin system). Although studies have suggested that calcium channel blocker (CCB) therapy mitigates the decline in renal function in humans with essential HTN, there are few long-term clinical studies that have determined the impact of CCBs in patients with hypertensive CKD. Dihydropyridine (DHP) or L-type CCBs preferentially vasodilate the afferent arteriole and have been associated with glomerular HTN and increases in proteinuria in animal models with low renal function. Small clinical studies in vulnerable populations with renal disease such as African Americans, children, and diabetics have also suggested that DHP CCBs exacerbate glomerular injury, which questions the renoprotective effect of this class of antihypertensive drug. We used an established integrative mathematical model of human physiology, HumMod, to test the hypothesis that DHP CCB therapy exacerbates pressure-induced glomerular injury in hypertensive CKD. Over a simulation of 3 yr, CCB therapy reduced mean blood pressure by 14-16 mmHg in HTN both with and without CKD. Both impaired tubuloglomerular feedback and low baseline renal function exacerbated glomerular pressure, glomerulosclerosis, and the decline in renal function during L-type CCB treatment. However, simulating CCB therapy that inhibited both L- and T-type calcium channels increased efferent arteriolar vasodilation and alleviated glomerular damage. These simulations support the evidence that DHP (L-type) CCBs potentiate glomerular HTN during CKD and suggest that T/L-type CCBs are valuable in proteinuric renal disease treatment.NEW & NOTEWORTHY Our physiological model replicates clinical trial results and provides unique insights into possible mechanisms that play a role in glomerular injury and hypertensive kidney disease progression during chronic CCB therapy. Specifically, these simulations predict the temporal changes in renal function with CCB treatment and demonstrate important roles for tubuloglomerular feedback and efferent arteriolar conductance in the control of chronic kidney disease progression.

Improvements in Augmentation Index and Urinary Albumin Excretion With Benidipine in Hypertensive Patients With Chronic Kidney Disease

Although calcium channel blockers (CCB) are expected to improve the augmentation index (AI) in CKD patients, the potential effect of benidipine on AI has been poorly studied.The present study aimed to compare the effect of benidipine and amlodipine in the treatment of CKD patients as measured through AI and urinary albumin excretion (UAE). Eligible patients with CKD were randomized to either the benidipine group or amlodipine group. Changes in UAE and AI were compared with target blood pressure level set at < 130/80 mmHg. A total of 108 patients were enrolled; 88 patients who were followed up were included in the analysis. Although no significant change in renal function was noted in either group, there was a significant improvement in AI only in the benidipine group (85.7 ± 13.3% to 81.4 ± 15.2%; P = 0.021) A subgroup analysis of 64 patients who achieved SBP < 140 mmHg at the end of follow-up (31 on amlodipine and 33 on benidipine) was carried out. Significant improvement in AI was noted only in the benidipine group (84.5 ± 13.6% to 79.5 ± 15.2%; P = 0.0138). In another subgroup of patients with UAE ≥ 300 mg/g Cr, a significant improvement in UAE in the benidipine group was found compared with the amlodipine group (-25 ± 46, 51 ± 60%, P = 0.031, respectively).These results suggest that benidipine might reduce significantly AI and might have potentially greater improvements in UAE than amlodipine in advanced CKD patients receiving RAS inhibitors.

Renal microcirculation and calcium channel subtypes

It has recently been reported that voltage-dependent Ca channel subtypes, e.g., L-, T-, N-, and P/Q-type, are expressed in renal arterioles and renal tubules, and the inhibition of these channels exerts various effects on renal microcirculation. For example, selective blockade of L-type Ca channels with nifedipine preferentially dilates the afferent arteriole and potentially induces glomerular hypertension. On the other hand, recently developed Ca channel blockers (CCBs) such as mibefradil and efonidipine block both T-type and L-type Ca channels and consequently dilate both afferent and efferent arterioles, leading to lowering of intraglomerular pressure. Interestingly, aldosterone has recently been recognized as a factor exacerbating renal diseases, and its secretion from adrenal gland is mediated by T-type Ca channels. Furthermore, T-type CCBs were shown to ameliorate renal dysfunction by suppressing inflammatory processes and renin secretion. On the basis of histological evaluations, N-type Ca channels are present in peripheral nerve terminals innervating both afferent and efferent arterioles. Further, it was suggested that N-type CCBs such as cilnidipine suppress renal arteriolar constriction induced by enhanced sympathetic nerve activity, thereby lowering intraglomerular pressure. Taken together, various Ca channel subtypes are present in the kidney and blockade of selective channels with distinct CCBs exerts diverse effects on renal microcirculation. Inhibition of T-type and N-type Ca channels with CCBs is anticipated to exert pleiotropic effects that would retard the progression of chronic kidney disease through modulation of renal hemodynamic and non-hemodynamic processes.

Combination therapy for hypertension in patients with CKD: a subanalysis of the Combination Therapy of Hypertension to Prevent Cardiovascular Events trial

The Combination Therapy of Hypertension to Prevent Cardiovascular Events (COPE) trial was a multicenter, randomized, three-arm comparative study (N=3293) undertaken to determine the optimal combination therapy, based on the occurrence of cardiovascular events in patients treated with an angiotensin II receptor blocker (ARB), a β-blocker (BB) or a thiazide diuretic (TD) in addition to the calcium antagonist benidipine as baseline medication. This subanalysis was conducted to compare the efficacy of three combination therapies in a subset of 834 patients with chronic kidney disease (CKD) (287 patients treated with benidpine-ARB, 283 patients treated with benidipine-BB and 264 patients treated with benidipine-TD). The incidence of composite cardiovascular events as the primary end point did not differ among these three groups. The incidence of hard end points and cerebrovascular events among these groups did not differ either, although the incidence among all patients in the COPE trial was lower in the benidipine-TD group than in the benidipine-BB group. The incidence of new-onset diabetes mellitus was higher in the benidipine-TD group than in the benidipine-ARB group among patients with CKD. The estimated glomerular filtration rate (eGFR) was maintained even after 12 months of treatment in patients with a baseline eGFR <60 ml min(-1) per 1.73 m(2) regardless of the treatment group, although the eGFR decreased over time in all patients in the three groups. In conclusion, in patients with CKD, all of the tested combination therapies demonstrated comparable efficacy in terms of prevention of cardiovascular events as well as maintenance of eGFR.

T-type Ca channel blockade as a determinant of kidney protection

Voltage-dependent Ca channels are classified into several subtypes based on the isoform of their α1 subunits. Traditional Ca channels blockers (CCBs), including nifedipine and amlodipine, act predominantly on L-type Ca channels, whereas novel CCBs such as efonidipine, benidipine and azelnidipine inhibit both L-type and T-type Ca channels. Furthermore, cilnidipine blocks L-type and N-type Ca channels. These CCBs exert divergent actions on renal microvessels. L-type CCBs preferentially dilate afferent arterioles, whereas both L-/T-type and L-/N-type CCBs potently dilate afferent and efferent arterioles. The distinct actions of CCBs on the renal microcirculation are reflected by changes in glomerular capillary pressure and subsequent renal injury: L-type CCBs favor an increase in glomerular capillary pressure, whereas L-/T-type and L-/N-type CCBs alleviate glomerular hypertension. The renal protective action of L-/T-type CCBs is also mediated by non-hemodynamic mechanisms, i.e., inhibition of the inflammatory process and inhibition of Rho kinase and aldosterone secretion. Finally, a growing body of evidence indicates that T-type CCBs offer more beneficial action on proteinuria and renal survival rate than L-type CCBs in patients with chronic kidney disease (CKD). Similarly, in CKD patients treated with renin-angiotensin blockers, add-on therapy with N-type CCBs is more potent in reducing proteinuria than that with L-type CCBs, although no difference is found in the subgroup with diabetic nephropathy. Thus, the strategy for hypertension treatment with CCBs has entered a new era: treatment selection depends not only on blood pressure control but also on the subtypes of CCBs.

Cell membrane stretch activates intermediate-conductance Ca2+-activated K+ channels in arterial smooth muscle cells

The aim of this study is to determine the signal transduction of membrane stretch on intermediate-conductance Ca(2+)-activated K(+) (IKca) channels in rat aorta smooth muscle cells using the patch-clamp technique. To stretch the cell membrane, both suction to the rear end of patch pipette and hypotonic shock were used. In cell-attached and inside-out patch configurations, the open probability of IKca channels increased when 20- to 45-mmHg suction was applied. Hyposmotic swelling efficiently increased IKca channel current. When the Ca(2+)-free solution was superfused, the activation of IKca current by the hyposmotic swelling was reduced. Furthermore, gadolinium (Gd(3+)) attenuated the activation of IKca channels induced by hyposmotic swelling, whereas nicardipine did not. In the experiments with Ca(2+)-free bath solution, pretreatment with GF109203X, a protein kinase C (PKC) inhibitor, completely abolished the stretch-induced activation of IKca currents. The stretch-induced activation of IKca channels was strongly inhibited by cytochalasin D, indicating a role for the F-actin in modulation of IKca channels by changes in cell stretching. These data suggest that cell membrane stretch activates IKca channels. In addition, the activation is associated with extracellular Ca(2+) influx through stretch-activated nonselective cation channels, and is also modulated by the F-actin cytoskeleton and the activation of PKC.

The N-type and L-type calcium channel blocker cilnidipine suppresses renal injury in Dahl rats fed a high-salt diet

The aims of the present study were to compare the effects of cilnidipine [L-type/N-type calcium channel blocker (CCB)] and amlodipine (L-type CCB) alone or in combination with the angiotensin II receptor blocker (ARB), valsartan, on blood pressure (BP), kidney function in Dahl salt-sensitive (DS) rats. DS rats fed a high-salt diet were divided into six groups; control (n = 13), two CCB (cilnidipine or amlodipine) groups at 1 mg/kg/day (n = 10), ARB (valsartan) at 10 mg/kg/day (n = 12), cilnidipine + valsartan (CV, n = 12), and amlodipine + valsartan (AV, n = 12). BPs were lower in the combination therapy groups than in those given either drug alone, but only CV inhibited the increase in urinary albumin excretion (UAE) and lowered the glomerular sclerosis score. In addition, AV elevated plasma renin activity and the angiotensin II concentration, and thus failed to inhibit increases in UAE and to lower glomerular sclerosis score. In conclusion, combination therapy with CCB and ARB decreases BP more effectively than either drug alone. When used in combination with valsartan, cilnidipine is more effective than amlodipine for preventing kidney injury.

Prevention of contrast-induced acute kidney injury by theophylline in elderly patients with chronic kidney disease

Although the optimal strategy for preventing contrast-induced acute kidney injury (CI-AKI) has not yet been established, the current strategy focuses on adequate periprocedural hydration, the use of a low amount of low or iso-osmolar contrast medium, and the application of adjunctive therapies, including hemofiltration, hemodialysis and drugs. Previous trials and meta-analyses concerning the use of the adenosine antagonist theophylline have revealed contradictory results. We sought to evaluate the effect of theophylline in CI-AKI prevention in well-hydrated elderly patients with chronic kidney disease. We therefore conducted a randomized, double-blind, placebo-controlled trial involving 56 patients who had been referred for cardiac coronary angiography and/or angioplasty. 31 of these patients were randomly assigned to 200 mg theophylline IV before the procedure, and 25 to a placebo. The iso-osmolar contrast medium iodixanol was used. The primary endpoint was an increase in serum creatinine at study termination 48 h after contrast medium administration. Baseline characteristics in the placebo and theophylline groups were similar in terms of median age (75 years), estimated glomerular filtration rate (33 ± 10 vs. 33 ± 10 ml/min/1.73 m²; p = 0.87), diabetes mellitus (80 vs. 71%; p = 0.54), and amount of contrast used (94 ± 35 vs. 95 ± 38 ml; p = 0.89). There was no difference in serum creatinine at baseline (2.06 ± 0.59 vs. 2.02 ± 0.45 mg/dl; p = 0.62) or study termination (2.06 ± 0.68 vs. 2.10 ± 0.53; p = 0.79). A prophylactic effect of theophylline was not observed. The incidence of renal impairment following exposure to the contrast medium was low. This fact can be attributed to adequate parenteral hydratation and the use of the minimum amount of contrast medium necessary.

Impact of renal function on cardiovascular events in elderly hypertensive patients treated with efonidipine

This study evaluated the impact of renal function on cardiovascular outcomes in elderly hypertensive patients enrolled in the Japanese Trial to Assess Optimal Systolic Blood Pressure in Elderly Hypertensive patients. The patients were randomly assigned to either a strict-treatment group (target systolic blood pressure (BP) <140 mm Hg, n=2212) or a mild-treatment group (target systolic BP, 140 to <160 mm Hg, n=2206), each with efonidipine (a T/L-type Ca channel blocker)-based regimens. Cardiovascular events (stroke, cardiovascular disease and renal disease) were evaluated during the 2-year follow-up period following the prospective randomized open-blinded end-point method. Estimated glomerular filtration rate (eGFR) was elevated throughout the trial period in both the strict-treatment (59.4-62 ml min⁻¹ per 1.73 m²) and the mild-treatment group (58.8-61.4 ml min⁻¹ per 1.73 m²). This tendency was also observed in diabetic patients and patients aged ≥75 years, with baseline eGFR<60 ml min⁻¹ per 1.73 m². Baseline eGFR (<60 vs. ≥60 ml min⁻¹ per 1.73 m²) had no definite relationship with the incidence of cardiovascular events, nor did the level of BP control. Proteinuria at the time of entry into the study, however, was significantly correlated with cardiovascular event rates (7.1%), an association that was more apparent in patients with eGFR<60 ml min⁻¹ per 1.73 m² (8.2%). Furthermore, the event rate was more elevated in patients with greater declines in eGFR and was amplified when the baseline eGFR was <60 ml min⁻¹ per 1.73 m². In conclusion, the rates of decline of renal function and proteinuria constitute critical risk factors for cardiovascular events in elderly hypertensive patients, trends that are enhanced when baseline eGFR is diminished. Furthermore, the fact that efonidipine-based regimens ameliorate renal function in elderly hypertensive patients with chronic kidney disease may offer novel information on the mechanisms of cardiovascular protection.