Verapamil limits shockwave-induced renal tubular damage in vivo

Role of TNF-associated cytokines in renal tubular cell apoptosis induced by hyperoxaluria

Crystal-cell interaction has been reported as one of the most crucial steps in urinary stone formation. Hyperoxaluria-induced apoptotic changes in renal tubular epithelial cells is the end-stage of this interaction. We aimed to evaluate the possible pathways responsible in the induction of apoptosis within the involved cells by assessing the receptoral expression of three different pathways. 16 male Spraque-Dowley rats were divided into two groups: Group 1 (n:8) received only distilled water; Group 2 (n:8) received 0.75 % ethylene glycol (EG) in their daily water to induce hyperoxaluria for 2 weeks. After 24 h urine collection, all animals were euthenized and right kidneys were removed and fixed for immunohistochemical evaluation. Oxalate and creatinine levels (in 24 h-urine) and FAS, tumor necrosis factor (TNF), TNF-related apoptosis-inducing ligand (TRAIL) and TRAIL receptor-2 expressions (in tissue) have been assessed. In addition to TNF (p = 0.0007) expression; both FAS (p = 0.0129 ) and FASL (p = 0.032) expressions significantly increased in animals treated with EG. The expressions of TRAIL (p = 0.49) and TRAIL-R2 (p = 0.34) receptors did not change statistically after hyperoxaluria induction. Although a positive correlation with cytokine expression density and 24 h-urinary oxalate expression (mg oxalate/mg creatinine) has been assessed with TNF (p = 0.04, r = 0.82), FAS (p = 0.05, r = 0.80), FAS-L (p = 0.04, r = 0.82); no correlation could be demonstrated between TRAIL and TRAIL R2 expressions. Our results indicate that apoptosis induced by oxalate is possibly mediated via TNF and FAS pathways. However, TRAIL and TRAIL-R2 seemed to have no function in the cascade. Correlation with urinary oxalate levels did further strengthen the findings.

Hyperoxaluria-induced tubular ischemia: the effects of verapamil and vitamin E on apoptotic changes with an emphasis on renal papilla in rat model

An experimental study in rats was performed to evaluate the presence and the degree of both tubular apoptotic changes and crystallization at cortical, medullar and papillary regions of the kidney during hyperoxaluric phase and assess the possible protective effects of vitamin E and verapamil on these pathologic changes (particularly in papillary part of the affected kidneys). A total of 32 rats have been included into the study program. Hyperoxaluria was induced by continuous administration of ethylene glycol (0.75%). In addition to hyperoxaluria induction, animals in Groups 2 and 3 did receive a calcium channel-blocking agent (verapamil) and vitamin E, respectively. Histologic alterations of the kidneys including crystal formation together with apoptotic changes were evaluated on days 1, 14 and 28, respectively. Both apoptotic changes and the presence and degree of crystallization were assessed separately in renal cortical region, medulla and particularly papillary parts of the removed kidneys. Although verapamil did well limit the degree of crystal formation and apoptosis and brought it to the same levels observed in control group animals in all parts of the kidneys during intermediate phase, addition of vitamin E was failed to show the same protective effect during both intermediate and late phase evaluations. As demonstrated in our study, the limitation of both crystal deposition and apoptotic changes might be instituted by calcium channel-blocking agents. Clinical application of such agents in the prophylaxis of stone disease might limit the formation of urinary calculi, especially in recurrent stone formers.

Rapid communication: renal apoptosis after shockwave application in rabbit model

PURPOSE

To identify any apoptotic effect of shockwave lithotripsy (SWL) on renal tubular and glomerular cells.

MATERIALS AND METHODS

Thirty-five male New Zealand White rabbits were divided into five groups of seven rabbits each: I (control), II (sham), and III, IV, and GV (treated and sacrificed 1, 7, and 28 days after SWL, respectively). Intramuscular anesthetic agent (ketamine HCl; 20 mg/kg) and intravenous contrast medium (iohexol 300 mg of I/mL) were administered to animals in group II. The left kidneys of animals in groups III, IV, and V were exposed to 2000 shockwaves at 18 kV after administration of anesthesia and contrast medium. The animals were sacrificed on day 1, 7, or 28 after SWL, and the kidneys were removed. Apoptotic and proliferative indices of renal tubular and glomerular cells were determined by terminal deoxynucleotidyl transferase dUTP nick and label (TUNEL) and Ki-67 labeling methods, respectively, counting 1000 cells in each preparation.

RESULTS

No apoptosis was detected in glomerular cells in any group. The mean apoptotic indices of the tubular cells in animals in groups I and II were 483.0 +/- 85 and 484.4 +/- 105, respectively with no significant difference between the groups. In groups III and IV, the mean apoptotic indices were 343.4 +/- 89 and 358.4 +/- 61, respectively. There were no statistically significant differences between groups III and IV and the control group. Similarly, there were no significant differences in the apoptotic indices in groups III and IV. However, the apoptotic index in group V was 821.4 +/- 57, significantly higher than in the control group. The proliferative indices of all SWL groups were lower than that of the control group.

CONCLUSION

Shockwave lithotripsy has an apoptotic effect on renal tubular cells that can be detected 4 weeks after the procedures, but no apoptotic effect on glomerular cells. Treatment with SWL also attenuates the proliferation of both tubular and glomerular cells.

The effect of calcium channel blockers on stone regrowth and recurrence after shock wave lithotripsy

We evaluated the possible effects of a calcium entry blocking agent "verapamil" on new stone formation and/or regrowth of residual fragments after shock wave lithotripsy (SWL) during long-term follow-up (>30 months) and compared the results with the success rates of adequate fluid intake. A total of 70 patients treated with SWL were randomly divided into three different groups, in the first two of which the patients received different preventive measures with respect to stone recurrence and/or regrowth. While 25 patients received a calcium channel blocking agent, verapamil hydrochloride, beginning 3 days before SWL and continued 4 weeks after the procedure, an additional 25 patients were put in an enforced fluid intake program and the remaining 20 patients received no specific medication and/or measure apart from close follow-up. Patients were followed regularly with respect to the clearance/regrowth of the residual fragments and that of new stone formation during long-term follow-up (within a mean follow-up of 30.4 months). The overall stone recurrence rate was 14% (10/70). Of the patients who became stone free (12/25, 48%) in group I, only one patient (1/12, 8.3%) showed a new stone formation during long-term follow-up. The figure was 40% (4/10) in group II patients and 55% (5/9) in group III patients receiving no specific medication. Regarding the residual stone fragments (<5 mm) after SWL, again high fluid intake was found to be the most effective on stone regrowth rates (2/13, 15.3%). Patients treated with verapamil also had acceptable regrowth rates (3/15, 20%). Finally, verapamil treatment significantly improved the clearance of residual fragments; while 7 out of 15 patients with residual fragments passed these particles successfully, (46.5%) in this group; these figures were 46% (6/13) and 18% (2/13) in the remaining groups. Residual fragments located in lower calyces demonstrated a poor clearance rate with higher regrowth rates. Verapamil administration was found to be effective enough to limit the regrowth of residual fragments and also to facilitate residual fragment clearance after SWL. Patients receiving this medication seemed to pass the retained fragments easily in a shorter time than the others.

Limitation of apoptotic changes in renal tubular cell injury induced by hyperoxaluria

Renal tubular epithelium is the major target for oxalate induced injury, and sustained hyperoxaluria together with CaOx crystal formation/deposition may induce renal tubular cell damage and/or dysfunction. This may express itself in cell apoptosis. To evaluate the possible protective effects of certain agents (vitamin E, potassium citrate, allopurinol, verapamil and MgOH) on the presence and the severity of apoptotic changes caused by hyperoxaluria on renal tubular epithelium, an experimental study in rabbits was performed. Seventy rabbits were divided into seven different groups (each group n = 10): in group I severe hyperoxaluria was induced by continuous ethylene glycol (0.75%) administration started on day 0 and completed on day 14. Histologic alterations including crystal formation together with apoptotic changes (by using the TUNEL method) were evaluated on days 21 and 42, respectively. In the remaining experimental groups (groups II-VI), animals received some agents in addition to the induction of hyperoxaluria in an attempt to limit apoptotic changes. Group VII) animals constituted the controls. Kidneys were examined histopathologically under light microscopy for the presence and degree of crystal deposition in the tubular lumen. The percentage of apoptotic nuclei in the control group was significantly different from the other group animals (2.9-2.4%) in all study phases (P < 0.05). Apart from potassium citrate and allopurinol, the other medications seemed to prevent or limit the formation of apoptotic changes in renal tubular epithelium during the early period (day 21). The percentage of positively stained nuclei in animals undergoing potassium citrate medication ranged from 24.3% to 28.6%, with an average of 27.1%. This was 18.4% in animals receiving allopurinol. On the other hand, animals receiving magnesium hydroxide (MgOH), verapamil and vitamin E demonstrated limited apoptotic changes (11.2, 9.7, 8.7%, respectively) during this phase(P < 0.05). In the long-term (day 42), the animals receiving allopurinol and vitamin E showed a decrease in the percentage of the positively stained nuclei (13.5% and 8.3%, respectively). Animals in the other groups showed an increase in the number and percentage of apoptotic cells. Although, there was a significant decrease in the mean values of apoptosis in animals receiving vitamin E (8.7%-8.3%) and allopurinol (18.4%-13.5%) (P < 0.05), animals on verapamil, MgOH and potassium citrate medication had an increase in these values or the change was not found to be significant. In the light of our findings and results from the literature, it is clear that that both hyperoxaluria and CaOx crystals may be injurious to renal epithelial cells. Apoptotic changes observed in renal tubular epithelial cells induced by massive hyperoxaluria might result in cell degradation and may play a role in the pathologic course of urolithiasis. Again, as demonstrated in our study, the limitation of both crystal deposition and apoptotic changes might be instituted by some antioxidant agents as well as urinary inhibitors. Clinical application of such agents in the prophylaxis of stone disease might limit the formation of urinary calculi, especially in recurrent stone formers.

Morphological changes induced in the pig kidney by extracorporeal shock wave lithotripsy: nephron injury

While shock wave lithotripsy (SWL) is known to cause significant damage to the kidney, little is known about the initial injury to cells along the nephron. In this study, one kidney in each of six juvenile pigs (6-7 weeks old) was treated with 1,000 shock waves (at 24 kV) directed at a lower pole calyx with an unmodified HM-3 lithotripter. Three pigs were utilized as sham-controls. Kidneys were fixed by vascular perfusion immediately after SWL or sham-SWL. Three of the treated kidneys were used to quantitate lesion size. Cortical and medullary samples for light (LM) and transmission electron microscopy (TEM) were taken from the focal zone for the shock waves (F2), the contralateral kidney, and the kidneys of sham-SWL pigs. Because preservation of the tissue occurred within minutes of SWL, the initial injury caused by the shock waves could be separated from secondary changes. No tissue damage was observed in contralateral sham-SWL kidneys, but treated kidneys showed signs of injury, with a lesion of 0.2% +/- 0.1% of renal volume. Intraparenchymal hemorrhage and injury to tubules was found at F2 in both the cortex and medulla of SWL-treated kidneys. Tubular injury was always associated with intraparenchymal bleeding, and the range of tissue injury included total destruction of tubules, focal cellular fragmentation, necrosis, cell vacuolization, and membrane blebbing. The initial injury caused by SWL was cellular fragmentation and necrosis. Cellular vacuolization, membrane blebbing, and disorganization of apical brush borders appear to be secondary changes related to hypoxia.

Limitation of shockwave-induced enhanced crystal deposition in traumatized tissue by verapamil in rabbit model

OBJECTIVE

To evaluate the possible protective effect of verapamil (a calcium channel blocking agent) against the traumatizing effects of high-energy shockwaves (HESW) and new stone formation, as indicated by crystal deposition in the renal parenchyma, an experimental study was performed in rabbits.

METHODS

A total of 65 rabbits were included. During severe hyperoxaluria induced by continuous ethylene glycol (EG) (0.75%) administration, animals in the first group (N = 15) received EG only, and animals in the second group underwent administration of 500 to 1500 shockwaves, animals in the third group (N = 15) received verapamil (0.1 mg/kg) for 3 days prior to HESW application, a control group (N = 15) received various numbers (500 to 1500) of shockwaves alone. Sham-treated animals (N = 5) constituted the last group in our study. Three months after shockwave application, tissue sections obtained from treated and untreated kidneys were evaluated histopathologically under light microscopy and transmission electron microscopy (TEM) for the presence and degree of crystal deposition in the cortical parenchymal region subjected to HESW.

RESULTS

Whereas crystal deposition was evident in the intercellular region and intratubular parts of the parenchyma in animals receiving EG and HESW, especially in those receiving relatively higher numbers of shockwaves), animals receiving verapamil demonstrated limited or no crystal formation. No significant crystal deposition could be noted in specimens from animals undergoing either EG or SWL alone, and sham-treated animals demonstrated no significant alteration, as expected.

CONCLUSION

Using this model, the traumatic effects of HESW could be evaluated as a factor in new stone formation after SWL. Verapamil has been found to be protective against crystal deposition.

Effects of an ACE inhibitor/calcium antagonist combination on proteinuria in diabetic nephropathy

BACKGROUND

The degree of proteinuria in patients with diabetes correlates strongly with both an increase in progression of nephropathy as well as cardiovascular events. Moreover, post hoc analyses of recent clinical trials support the concept that reductions of blood pressure and proteinuria correlate with a slowed progression of nephropathy. Both angiotensin converting enzyme (ACE) inhibitors and the nondihydropyridine calcium antagonists, (non-DHPCAs) reduce both arterial pressure and proteinuria in those with diabetic nephropathy.

METHODS

The present randomized, open label, parallel group designed study tests the hypothesis that, at similar levels of blood pressure, the combination of an ACE inhibitor, trandolapril (T) with the non-DHPCA, verapamil (V) produces a greater reduction in proteinuria over either agent alone at one year. Thirty-seven participants, mean age 59.6 +/- 5.8 years, with nephropathy (baseline creatinine 1.4 +/- 0.3 mg/dl and proteinuria of 1342 +/- 284 mg/dl) secondary to type 2 diabetes completed the study. Doses of drug were titrated in each group over eight weeks to achieve a goal blood pressure of < 140/90 mm Hg. All participants were counseled to ingest a sodium diet of < 120 mEq/day.

RESULTS

Proteinuria reduction from baseline was significantly greater in the T+V group compared to either T alone (-33 +/- 8%, T vs. -62 +/- 10%, T+V; P < 0.001) or V alone (-27 +/- 8%, V vs. -62 +/- 10%, T+V; P < 0.001). No significant differences in either glomerular filtration rate, arterial pressure, fasting blood glucose or urinary sodium excretion were noted at one year. The mean daily dose of the individual components of T+V (2.9 +/- 0.8 mg, T/219 +/- 21.1 mg V) was significantly lower than the dose of either T alone 5.5 +/- 1.1 mg/day (P < 0.01) or V alone 314.8 +/- 46.3 mg, given in two divided doses (P < 0.01).

CONCLUSION

These data support the concept that the combination of an ACE inhibitor with a non-DHPCA reduce proteinuria to a greater extent than either agent alone. This added antiproteinuric effect occurs at lower doses of each drug and is independent of further reductions in arterial pressure. These findings could have ramifications for slowing renal disease progression in patients with nephropathy from type 2 diabetes.

Preservation of shock-wave-induced renal histologic changes by dermatan sulfate

OBJECTIVES

To evaluate the protective effects of glycosaminoglycan (GAG) administration on shock-wave-induced renal histologic alterations, an experimental study using dermatan sulfate administration (DS) in rabbits was performed.

METHODS

The study included 45 white New Zealand rabbits; 36 were divided into two groups before shock-wave application. Animals in the first group (n = 18) received no specific medication before or after shock-wave treatment; animals in the second group (n = 18) received subcutaneous DS administration for a period of 2 months, beginning 2 weeks before shock-wave application. Following different numbers of shock-wave application (500, 1000, or 1500 shock waves), histopathologic evaluation of treated kidneys was made under light microscopy after 24 hours and 3 months. Nine animals were used for the control group.

RESULTS

During 24-hour examination, most of the kidneys in both groups demonstrated varying degrees of histopathologic alterations, depending on the number of shock waves applied. Among the most prominent pathologic features were protein deposition with free erythrocytes in the tubular lumen, glomerular hemorrhage, tubular dilation and degeneration, protein in Bowman's capsule, hyperemia, and mononuclear cell infiltration at the interstitial level. As opposed to the 24-hour evaluation findings, long-term (3-month) follow-up examination revealed histopathologic alterations that decreased but did not totally disappear in animals receiving no DS. Glomerular basement membrane thickening, mononuclear cell infiltration and limited protein deposition in some tubules, together with cortical interstitial fibrosis, were observed to some extent in these animals. On the other hand, no severe histopathologic alteration with normal glomerular basement membrane appearance was noted in animals receiving DS medication.

CONCLUSIONS

Our results indicated a long-term favorable protective effect of DS administration on morphologic abnormalities in rabbits undergoing shock-wave treatment. Although tubular alterations persisted to some extent, mononuclear cell infiltration has been limited and the natural appearance of the basement membrane has been well preserved in most of the treated animals.

Effect of extracorporeal shockwave lithotripsy on plasma and urine endothelin concentrations

Since the first reports of extracorporeal shockwave lithotripsy (SWL), there have been increasing numbers of articles in the literature documenting renal blood flow impairment and blood pressure elevation as complications. However, little is known about the pathophysiology and prevention of these complications. In this prospective study, the influence of high-energy shockwaves on plasma and urine endothelin concentrations was investigated in 20 patients with renal stones. The patients were randomly assigned to receive a calcium channel blocker, 10 mg of nitrendipine (Bypress; Bayer) (N = 10) 2 hours before SWL or no medication (control group; N = 10). Blood samples were taken just before and 1 minute after application of 3000 shocks. Urine samples were collected by ureteral catheters. The plasma endothelin-1 concentrations were significantly elevated after SWL in the control group (P = 0.003). On the other hand, nitrendipine significantly reduced plasma endothelin concentrations after SWL (P = 0.003). No significant change was observed in urine samples and blood pressure measurements. These results suggest that endothelin release after SWL may be a cause for lithotripsy-induced hemodynamic changes. Medical prevention with calcium channel blockers warrants further investigation.

Protective effect of verapamil on renal tissue during shockwave application in rabbit model

Although extracorporeal shockwave lithotripsy (SWL) is the treatment of choice for symptomatic urinary calculi, it has been shown in number of studies that adverse effects of high-energy shockwaves may be encountered in short- and long-term follow-up. To evaluate the possible protective effect of verapamil administration on renal tissue, both magnetic resonance imaging (MRI) and histopathologic examination were performed after SWL in rabbits. Thirty-five animals were divided into three groups. The 15 animals in the first group were fed verapamil (0.1 mg/kg) for 3 days. Another 15 animals received no medication but underwent SWL, and the remaining 5 animals received anesthesia alone (sham group). The animals were then subdivided into three groups according to the shockwave number applied (1000, 15,000, or 2000) and the aforementioned evaluations were performed 24 hours and 3 months after the procedure. We found prominent histopathologic alterations in animals not receiving any medication before SWL. Persistence of these pathologic alterations during 3 months of follow-up indicated the importance of preservation of renal architecture during high-energy shockwave application. On the other hand, animals under verapamil medication prior to SWL demonstrated only a limited degree of histopathologic alteration. Demonstration of a normal histologic pattern after 3 months supported the preservation of tissue structure by such medication. No significant histopathologic alteration could be observed in the sham-group animals, as expected. Our study demonstrates that verapamil is protective against shockwave-induced renal tubular damage. Such medications may be useful to avoid the proven histopathologic and functional side effects of high-energy shockwaves.