Elevated Plasma Renin Activity Research Articles

Novel CYP11B2 mutation causing aldosterone synthase (P450c11AS) deficiency

Aldosterone synthase (P450c11AS) deficiency is a rare autosomal recessive disorder, presenting with severe salt-losing in early infancy. It is caused by inactivating mutations of the CYP11B2 gene. Here, we describe three unrelated Asian patients who have clinical and hormonal features compatible with aldosterone synthase deficiency and identify their CYP11B2 mutations. Patient 1 was a Thai female infant. Patient 2 was an Indian boy, and patient 3 was a Thai male infant. All subjects presented at the age of 1-2 months with diarrhea, failure to thrive, and severe dehydration. Their plasma electrolytes showed hyponatremia, hyperkalemia, and acidosis. All patients had normal cortisol response and had elevated plasma renin activity with low aldosterone levels. The entire coding regions of the CYP11B2 gene were amplified by polymerase chain reaction and sequenced. Patient 1 was homozygous for a previously described mutation, p.T318M. Patient 2 was homozygous for a novel c.666delC mutation inherited from both parents resulting in p.223F>Sfsx295. No CYP11B2 mutation was detected in patient 3. We report the first CYP11B2 defects in Southeast Asian families responsible for aldosterone synthase deficiency and identified a novel CYP11B2 mutation. However, the affected gene(s) responsible for primary hypoaldosteronism other than CYP11B2 remain to be determined.

The influence of extracellular and intracellular calcium on the secretion of renin

Changes in plasma, extracellular, and intracellular calcium can affect renin secretion from the renal juxtaglomerular (JG) cells. Elevated intracellular calcium directly inhibits renin release from JG cells by decreasing the dominant second messenger intracellular cyclic adenosine monophosphate (cAMP) via actions on calcium-inhibitable adenylyl cyclases and calcium-activated phosphodiesterases. Increased extracellular calcium also directly inhibits renin release by stimulating the calcium-sensing receptor (CaSR) on JG cells, resulting in parallel changes in the intracellular environment and decreasing intracellular cAMP. In vivo, acutely elevated plasma calcium inhibits plasma renin activity (PRA) via parathyroid hormone-mediated elevations in renal cortical interstitial calcium that stimulate the JG cell CaSR. However, chronically elevated plasma calcium or CaSR activation may actually stimulate PRA. This elevation in PRA may be a compensatory mechanism resulting from calcium-mediated polyuria. Thus, changing the extracellular calcium in vitro or in vivo results in inversely related acute changes in cAMP, and therefore renin release, but chronic changes in calcium may result in more complex interactions dependent upon the duration of changes and the integration of the body's response to these changes.

Resistant hyponatremia and hypokalemia treated successfully with nephrectomy.

Persistent hyponatremia and hypokalemia in the setting of hypertension may be a manifestation of an underlying hyperreninemic state. We present here a case of a patient who presented with a constellation of hypertension with severe polydipsia, subnephrotic proteinuria, with resistant hyponatremia and hypokalemia. Workup revealed an elevated plasma renin activity and elevated plasma aldosterone. Magnetic resonance imaging of the renal vasculature revealed complete occlusion of the right renal artery and a nuclear medicine renal scan showed a split renal function of 87% for the left kidney and 13% for the right kidney. The use of angiotensin receptor blockers (ARB) and angiotensin-converting enzyme (ACE) inhibitors was contraindicated due to a history of angioedema. Nephrectomy of the ischemic kidney was thus planned, and it resulted in a dramatic and complete resolution of his laboratory abnormalities and hypertension.

Type IV neonatal Bartter syndrome complicated with congenital chloride diarrhea

SummaryBackground:Pseudo-Bartter syndrome encompasses a heterogenous group of disorders similar to Bartter syndrome. Sometimes a few status may be nested, as in our case presented here.Case Report:An 8-month-old boy was referred to our hospital with of intractable diarrhea, polyuria, persistent hypokalemia, abdominal distension and failure to thrive. He was born in the 34 6/7 gestational week (GW) to consanguineous parents. In the 30th GW polyhydramnios was verified by ultrasonography. The laboratory results showed hypokalemic-hypochloremic metabolic alkalosis, hyponatremia, and increased urinary loss of chloride, potassium and calcium. An audiogram test revealed complete sensorineural deafness. Ultrasonography revealed medullary nephrocalcinosis in both kidneys. Elevated plasma renin activity and aldosterone were found and a provisional diagnosis of type-IV neonatal Bartter syndrome was made. Treatment with indomethacin, spironolactone and additional intake of NaCl/KCl was initiated. Despite these therapies, the child’s diarrhea persisted but serum potassium concentration normalized, and hypercalciuria and urine output reduced. After determining the high fecal chloride concentration, there was an immediate decompensation of the disease on indomethacin withdrawal, thus a diagnosis of type IV neonatal Bartter syndrome complicated with congenital chloride diarrhea was considered. Indomethacin, spironolactone and supplementary therapies with NaCl/KCl were continued, which resulted in the normalization of serum electrolytes as well as his physical development, but high contents of chloride in urine and faeces and nephrocalcinosis remains unchanged during 1-year follow-up.Conclusions:Because of the clinical and laboratory simulations between the various diseases that lead to hypokalemic-hypochloremic metabolic alkalosis, patients must be evaluated carefully.

Metoprolol Ameliorates Cyclosporine A–induced Hypertension and Nephrotoxicity in Rats

Despite their clinical relevance as important cardiovascular modulators, there are few studies regarding the potential protective effect of β-blockers against immunosuppressive-induced cardiovascular side effects. This study investigated the possible ameliorating effect of β1-blocker, metoprolol (MTP), against both hypertensive and nephrotoxic effects of cyclosporine A (CSA). Compared with vehicle (olive oil)-treated rats, chronic treatment with CSA (20 mg·kg·d subcutaneous, for 14 days) increased systolic blood pressure, elevated renal function indices and plasma renin activity, impaired renovascular responsiveness of isolated perfused rat kidneys to endothelium-dependent vasodilations induced by carbachol. These effects were abolished upon concurrent administration of MTP (5 mg·kg·d for 14 days, intraperitoneal). The possibility that alterations in the antioxidant and/or circulating cytokine levels contributed to the CSA-MTP interaction was also investigated. MTP abrogated the oxidative (superoxide dismutase, catalase), lipid peroxidation (malondialdyde), and elevated the cytokine (TNF-α and TGF-β) effects of CSA. Histologically, CSA caused tubular brush border loss and isometric vacuolization clustered in the proximal tubule; this effect disappeared in rats cotreated with MTP. The use of a nonhypotensive dose of MTP (1.25 mg/kg) countered in part endothelium dysfunction altered oxidative stress parameters and cytokine levels in CSA-treated rats. Collectively, MTP abrogates both the hypertensive and the nephrotoxic effects of CSA via ameliorating endothelium dysfunction, oxidative stress, and upregulated cytokine levels caused by CSA. The demonstration of nephroprotection by the low dose of MTP suggests that its renal effect may be partially unrelated to its hemodynamic activity.

Renal Responses to Magnesium Lithospermate B

Renal responses to magnesium lithospermate B isolated from Salviae miltiorrhizae radix were examined in normal rats. Urinary sodium, potassium, prostaglandin E2 and kallikrein excretion was significantly increased after magnesium lithospermate B administration, whereas excretion of urinary 6-keto-prostaglandin F1 alpha and thromboxane B2 was unchanged. Rats administered with the drug also revealed a slight elevation of plasma renin activity and the levels of angiotensins I and II. Plasma aldosterone was decreased slightly. No significant changes were observed in angiotensin-converting enzyme or blood pressure.

Clinical Features of Malignant Hypertension with Thrombotic Microangiopathy

Thrombocytopenia, microangiopathic hemolytic anemia, and elevated serum lactate dehydrogenase (LDH) clinically characterize thrombotic microangiopathy (TMA), which is frequently recognized among patients with malignant hypertension (MH). Sixteen consecutive patients with MH were retrospectively investigated over a 7-year period and clinical features of the subjects with TMA were evaluated. We confirmed TMA relevant to MH by the normalization of the platelet count and LDH after adequate blood pressure (BP) control was achieved. Thrombotic microangiopathy was found in 7 (44%) of 16 patients. All 7 patients had an elevated plasma renin activity (PRA). Although no significant differences were observed in PRA, the patients with TMA had a significantly higher plasma aldosterone (ALDO) (median: 403 pg/ml; IR: 305 to 568) in comparison to those without TMA (median: 220 pg/ml; IR: 147 to 287; p = 0.013). Overall, ALDO correlated with LDH (r = 0.634, p = 0.0095). However, no significant association was observed between PRA and LDH (r = 0.336, p = 0.2263). The median platelet count nadir of the patients with TMA was 8.4 × 104 per μl (IR: 7.15 to 9.95). Thrombocytopenia and elevated LDH were normalized, along with a gradual improvement of BP within an average of 5 days and 21.7 days, respectively. These results suggest that ALDO, but not PRA, may act as a potent indicator of the magnitude of vascular and organ damage related to TMA among patients with malignant hypertension (MH).

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 1mg/kg/day (n=10), ARB (valsartan) at 10mg/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.

Elevated Plasma Renin Activity Predicts Adverse Outcome in Chronic Heart Failure, Independently of Pharmacologic Therapy: Data From the Valsartan Heart Failure Trial (Val-HeFT)

Background The prognostic value of plasma renin activity (PRA) in chronic heart failure (HF) has been assessed before the widespread use of angiotensin-converting enzyme inhibitors (ACEi) and beta-blockers, which exert opposite effects on renin secretion. We evaluated the association between PRA and outcome in patients with chronic HF treated with ACEi and beta-blockers. Methods and Results PRA was measured in 4,291 patients from the Valsartan Heart Failure Trial (Val-HeFT). The prognostic performance of PRA in patients who were or were not taking ACEi or beta-blockers was evaluated by multivariable Cox models. PRA was elevated in patients on ACEi (median 5.85 [interquartile range (IQR) 1.82–17.83] ng/mL/h) compared with those not on ACEi (1.57 [0.74–4.15] ng/mL/h), and lower in those on beta-blockers (3.89 [1.17–12.61] ng/mL/h) than in those not on beta-blockers (6.21 [1.97–19.24] ng/mL/h). Lower systolic blood pressure, higher plasma aldosterone, and ACEi were associated with high PRA. Higher PRA was a strong and independent predictor of mortality in the whole population and in patients who were or were not treated with ACEi or beta-blockers. Conclusions PRA is a powerful prognostic marker of death over a wide range of concentrations in patients with chronic HF. Prescription of ACEi and/or beta-blockers does not influence the relation between PRA and outcome.

Relation of Elevated Plasma Renin Activity at Baseline to Cardiac Events in Patients With Angiographically Proven Coronary Artery Disease

Plasma renin activity (PRA) is a measure of renin-angiotensin system activity and is associated with cardiovascular outcomes in patients with heart failure (HF). We conducted a prospective analysis to assess whether elevated baseline PRA is associated with cardiovascular outcomes in 1,165 patients with coronary artery disease (> or =70% stenosis on the coronary angiogram) enrolled in the Intermountain Heart Collaborative Study. The exclusion criteria included previous myocardial infarction (MI) or HF, ejection fraction < or =45%, and a discharge diagnosis of MI/beta-blocker treatment. Baseline PRA measurements were evaluated as risk categories (< or =0.50, 0.51 to 2.30, and >2.30 ng/ml/h) and as tertiles (< or =0.40, 0.41 to 1.90, and > or =1.90 ng/ml/h). Predefined cardiovascular outcomes were assessed for a minimum follow-up of 3 years (mean 6.4 +/- 3.2, maximum 14.6) using Cox regression analysis to adjust for the baseline characteristics. The mean patient age was 64.4 years; most patients were men (73.1%) and hypertensive (63.2%). Elevated baseline PRA (high vs low category; >2.30 vs < or =0.50 ng/ml/h) was associated with a significantly increased risk of 3-year cardiac morbidity/mortality (hazard ratio 1.96; p = 0.004), MI (hazard ratio 2.41; p = 0.02), HF hospitalization (hazard ratio 4.39; p = 0.03), and all-cause death (hazard ratio 1.80; p = 0.01). Elevated baseline PRA was also associated with longer-term HF hospitalization (hazard ratio 2.12; p = 0.004) and all-cause death (hazard ratio 1.56; p = 0.002). Similar results were observed for the PRA tertiles. The association of PRA with outcomes was observed after correction for hypertension, hyperlipidemia, diabetes, a family history of cardiovascular events, smoking, renal failure, and the use of statins. In conclusion, elevated baseline PRA is associated with cardiac morbidity and mortality in patients with coronary artery disease but normal left ventricular function and no previous MI or HF.

Comparative efficacy and safety of aliskiren and irbesartan in patients with hypertension and metabolic syndrome

Metabolic syndrome, a cluster of risk factors that increase the risk of cardiovascular morbidity and mortality, is common in patients with hypertension. Chronic renin-angiotensin-aldosterone system (RAAS) activation, shown by elevated plasma renin activity (PRA), is implicated in many of the features of metabolic syndrome. The direct renin inhibitor aliskiren may be of benefit in this patient group as aliskiren targets the RAAS at the rate-limiting step. In this double-blind study, 141 patients with hypertension (mean baseline BP 155/93 mm Hg) and metabolic syndrome (modified National Cholesterol Education Program ATP III criteria) were randomized to aliskiren 300 mg or irbesartan 300 mg once daily. Patients treated with aliskiren 300 mg had their mean sitting blood pressure (BP) lowered by 13.8/7.1 mm Hg after 12 weeks, significantly greater (P≤0.001) than the 5.8/2.8 mm Hg reduction observed in patients treated with irbesartan 300 mg. A significantly greater proportion of patients treated with aliskiren achieved BP control to <135/85 mm Hg (29.2 vs 16.7% with irbesartan; P=0.019). Aliskiren treatment led to a 60% decrease in PRA from baseline, whereas irbesartan increased PRA by 99% (both P<0.001). Aliskiren and irbesartan had similar effects on glucose and lipid profiles and on a panel of biomarkers of inflammation and cardiovascular risk. Both aliskiren and irbesartan were well tolerated. Collectively, these results suggest that aliskiren 300 mg may offer treatment benefits compared with irbesartan 300 mg for BP reduction in patients with hypertension and metabolic syndrome.

Hydrogen Sulfide Inhibits Plasma Renin Activity

The development of renovascular hypertension depends on the release of renin from the juxtaglomerular (JG) cells, a process regulated by intracellular cAMP. Hydrogen sulfide (H2S) downregulates cAMP production in some cell types by inhibiting adenylyl cyclase, suggesting the possibility that it may modulate renin release. Here, we investigated the effect of H2S on plasma renin activity and BP in rat models of renovascular hypertension. In the two-kidney-one-clip (2K1C) model of renovascular hypertension, the H2S donor NaHS prevented and treated hypertension. Compared with vehicle, NaHS significantly attenuated the elevation in plasma renin activity and angiotensin II levels but did not affect plasma angiotensin-converting enzyme activity. Furthermore, NaHS inhibited the upregulation of renin mRNA and protein levels in the clipped kidneys of 2K1C rats. In primary cultures of renin-rich kidney cells, NaHS markedly suppressed forskolin-stimulated renin activity in the medium and the intracellular increase in cAMP. In contrast, NaHS did not affect BP or plasma renin activity in normal or one-kidney-one-clip (1K1C) rats, both of which had normal plasma renin activity. In conclusion, these results demonstrate that H2S may inhibit renin activity by decreasing the synthesis and release of renin, suggesting its potential therapeutic value for renovascular hypertension.

Aliskiren/valsartan combination for the treatment of cardiovascular and renal diseases

Chronic activation of the renin–angiotensin–aldosterone system (RAAS) plays a key role in the development of hypertension, and cardiac and renal diseases. RAAS inhibitors, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), improve cardiovascular and renal outcomes. However, studies have shown that residual morbidity and mortality remains high, despite current optimal treatment. More comprehensive control of the RAAS might provide additional reductions in morbidity and mortality. Direct renin inhibitors offer the potential for enhanced RAAS control as they target the system at the point of activation, thereby reducing plasma renin activity (PRA); by contrast, ARBs and ACE inhibitors increase PRA. Elevated PRA is independently associated with cardiovascular morbidity and mortality. A single-pill combination of the direct renin inhibitor, aliskiren, and the ARB, valsartan, at once-daily doses of 150/160 mg and 300/320 mg, has recently been approved by the US FDA for the treatment of hypertension in patients not adequately controlled on aliskiren or ARB monotherapy, and as initial therapy in patients likely to need multiple drugs to achieve their blood pressure goals. This article examines the efficacy, safety and tolerability of aliskiren/valsartan combination therapy, and considers the evidence for the potential organ-protection benefits of this treatment.

Relationship of Plasma Renin With a Prothrombotic State in Hypertension: Relevance for Organ Damage

Components of the renin-angiotensin-aldosterone system (RAAS) and a prothrombotic state are predictors of cardiovascular events in hypertensive patients. A relationship between the RAAS and the coagulation/fibrinolytic systems has been demonstrated, but its clinical relevance in hypertension is unclear. We investigated the relationships of the RAAS and the hemostatic system with hypertensive organ damage. Plasma components of the RAAS and parameters that directly assess the activation of coagulation and fibrinolysis were measured in 247 essential hypertensive patients in whom the extent of organ damage had been characterized at the cardiac, renal, and vascular level. Positive association with increasing plasma renin activity (PRA) was demonstrated for plasma fibrinogen, D-dimer, and plasminogen activator inhibitor-1 (PAI-1) levels. PRA was directly correlated with plasma aldosterone, fibrinogen, d-dimer, and PAI-1. The relationship of PRA with fibrinogen and PAI-1 remained significant after correction for age, gender, duration of hypertension, and smoking status. Plasma aldosterone levels were directly correlated with fibrinogen, D-dimer, and PAI-1, whereas plasma angiotensin-converting enzyme was not related with any of the coagulation parameters. Elevated PRA, aldosterone, fibrinogen, D-dimer, prothrombin fragment 1+2, and PAI-1 levels were associated with clinical and/or instrumental evidence of hypertension-related cardiac and renal damage. Both fibrinogen and PAI-1 were independent predictors of the presence of organ damage and their inclusion in a multivariate model eliminated PRA and aldosterone as independent predictors. A strong and independent association exists between renin, aldosterone, and markers of a prothrombotic state in essential hypertension. This relationship might contribute to the development of hypertensive organ damage.

Vasoconstrictor-induced hypertension following multiple blood transfusions in children with congenital hemolytic anemia.

Introduction. The mechanism by which blood transfusion increases blood pressure in a substantial proportion of patients with congenital hemolytic anemia is unknown. Vascular endothelium dysfunction and increased endogenous vasoactive substances have been postulated in the pathogenesis of hypertension following multiple blood transfusions. The present study was undertaken to test the hypothesis whether increased circulating vasoconstrictors following blood transfusions, if documented, is a potent modulator of hypertension in patients with congenital anemia. Materials and Methods. Four children with congenital hemolytic anemia developed severe hypertension and convulsions 2 to 4 days after they received multiple blood transfusions. None had a history of prior hypertension, kidney disease or seizures before the blood transfusion. Baseline blood and urine samples were obtained for routine renal function studies. Blood samples were also drawn during and 2 weeks after the clinical events for determination of epinephrine, norepinephrine, dopamine, and plasma renin activity. Results. Kidney function was normal in all the 4 patients. All had elevated plasma renin activity and increased blood epinephrine, norepinephrine, and dopamine concentrations during hypertensive crises. Hypertension responded to antihypertensive drugs with the patients remaining normotensive 3 to 6 days after commencing therapy. All recovered without further seizures. The elevated plasma renin activity, epinephrine, norepinephrine, and dopamine levels returned to reference levels 2 weeks after completion of the last blood transfusion. Conclusions. These data suggest that increased activity of vasoconstrictors in the recipient plasma may be responsible for the development of hypertension after multiple blood transfusions.

Severity of Virilization of External Genitalia in Japanese Patients with Salt-wasting 21-hydroxylase Deficiency

Females with salt-wasting (SW) 21-hydroxylase deficiency (21OHD) may present with mild external genitalia virilization, despite complete or almost complete enzyme inactivation. We therefore analyzed genotype/phenotype correlation in 13 Japanese female patients with SW 21OHD. Criteria for classification into the SW phenotype included history of a salt-losing crisis with documented hyponatremia, hyperkalemia, and markedly elevated plasma renin activity. Urologists and pediatricians determined the Prader genital stage and classified the location of the vaginal entrance into the common urogenital sinus as low, moderate, or high. CYP21A2 gene, coding for 21-hydroxylase, was analyzed with Southern blotting and direct sequencing. Genotypes were categorized into four mutation groups, based on the degree of enzymatic activity (N, complete enzyme inactivation; groups A, < 2%, B, 3-7%, and C > 30%). Basal androgen levels were available from only six out of thirteen patients, so we could not relate androgen levels with the severity of external genitalia virilization. We compared the degree of external genitalia virilization with genotype. The severity of external genitalia virilization varied from Prader stage 1 to 4. One patient who presented with Prader 1 had a genotype consistent with Group B. In addition, discordance between Prader classification and the location of the vaginal entrance was noted; one patient classified as Prader 4 showed low vaginal entrance, while another patient classified as Prader 3 showed high vaginal entrance. The degree of the impairment of 21-hydroxylase activity does not correlate with the severity of virilization of the external genitalia in female patients with the SW type of 21OHD.

Effects of V2-receptor antagonist tolvaptan and the loop diuretic furosemide in rats with heart failure

Diuretics are frequently required to treat fluid retention in patients with chronic heart failure (CHF). Unfortunately, they can lead to a decline in renal function, electrolyte depletion, and neurohormonal activation. Arginine vasopressin (AVP) promotes renal water reabsorption via the V2 receptor (V2R) and its levels are increased in CHF. This study was conducted to characterize the diuretic effect of tolvaptan, a non-peptide AVP V2R antagonist, and furosemide, a loop diuretic in a rat model of CHF after experimental autoimmune myocarditis. CHF was elicited in Lewis rats by immunization with porcine cardiac myosin, and 28 days after immunization rats were treated for 28 days with oral tolvaptan, and furosemide. CHF was characterized by left ventricular remodeling and impaired systolic and diastolic function. Tolvaptan produces a diuresis comparable to furosemide. Unlike tolvaptan, furosemide significantly increased urinary sodium and potassium excretion. Tolvaptan markedly elevated electrolyte-free water clearance (E-CH2O) or aquaresis to a positive value and increased urinary AVP excretion. In contrast to tolvaptan, furosemide elevated only electrolyte clearance (E-Cosm) but not E-CH2O. The differences in diuretic profile reflected the changes in plasma sodium and hormone levels. Tolvaptan dose dependently elevated plasma sodium concentration, but furosemide tended to decrease it. Furosemide significantly elevated plasma renin activity and aldosterone concentration. On the other hand, tolvaptan did not affect these parameters. Our results suggest that, tolvaptan have a potential medical benefit for the treatment of edematous conditions in CHF by removing excess water from the body without activating the RAAS or causing serum electrolyte imbalances.

Effects of Benazepril Hydrochloride in Cats with Experimentally Induced or Spontaneously Occurring Chronic Renal Failure

We examined effects of an angiotensin converting-enzyme inhibitor, benazepril hydrochloride (BH), on renal hypertension and chronic renal failure (CRF) in cats. For experimental CRF, healthy cats (n=5) underwent 7/8 renal ablation. After renal insufficiency and hypertension were confirmed by blood urea nitrogen (BUN), serum creatinine, creatinine clearance and telemetric recording of systemic blood pressure, BH was administered orally once daily at 0.9 to 2.0 mg/kg/day for 2 to 3 weeks. Within 2 months after renal ablation, renal failure and hypertension developed as evidenced by significant increases in BUN, serum creatinine and systemic blood pressure (p<0.01 or 0.05) and significantly decreased creatinine clearance accompanied by elevated plasma renin activity, angiotensin I and II, and aldosterone (p<0.01 or 0.05). BH administration corrected systemic hypertension (p<0.05) and significantly reduced angiotensin II and aldosterone (p<0.05). Upon discontinuation of BH, these values returned to the pre-administration levels. Studies on spontaneous CRF enrolled 11 cats with spontaneously occurring CRF. BH was administered orally to 6 cats once daily for 24 weeks at a final dose of 1.0 mg/kg/day, while 5 cats served as control. BH administration reduced serum creatinine and urinary protein concentration in every cat. Results demonstrate that in cats, loss of renal mass leads to activation of the renin-angiotensin-aldosterone system and associated renal hypertension, and indicate that BH is effective in correcting renal hypertension and may provide renal benefits to cats with CRF.

Refractory hyponatremia

Refractory hyponatremia

Type 2 Pseudohypoaldosteronism: New Insights Into Renal Potassium, Sodium, and Chloride Handling

Type 2 Pseudohypoaldosteronism: New Insights Into Renal Potassium, Sodium, and Chloride Handling