Changes in active and inactive renin and in angiotensin II across the kidney in essential hypertension and renal artery stenosis

Investigations were performed in 26 patients with essential hypertension and 24 with unilateral renal artery stenosis. In each patient blood was drawn simultaneously and in triplicate, from both renal veins and aorta, for measurement of plasma concentrations of active and inactive renin and of angiotensin II. In 19 patients estimates of individual renal plasma flow were obtained in order to calculate secretion rates for active and inactive renin, and to assess the contribution of renin secretion rate and of renal plasma flow to the renal vein renin ratio. In patients with essential hypertension there was evidence that the kidney secreted active renin (18% mean increase in renal vein concentration above that of arterial plasma; P less than 0.001), but no evidence of secretion of inactive renin (4% mean increase; NS). There was a tendency for the kidney to extract angiotensin II (8% mean decrease in renal vein concentration below that of arterial plasma; P = 0.07). The affected kidney in patients with renal artery stenosis showed marked secretion of active renin (364% mean increase; P less than 0.001) and also secreted inactive renin (80% mean increase; P less than 0.05) with net generation of angiotensin II across the renal circulation (100% mean increase; P less than 0.05). The contralateral kidney exhibited suppressed secretion of active renin (3% mean increase; NS) with no evidence of secretion of inactive renin (2% mean increase; NS), and marked extraction of angiotensin II (50% mean decrease; P less than 0.001). The correlation between combined secretion rate of active renin by both kidneys and the arterial concentration of active renin in patients with essential and renovascular hypertension taken together was strongly positive (r = 0.82; P less than 0.01). The same correlation for inactive renin was weak (r = 0.32; NS). The correlation between the combined secretion rates of active renin by both kidneys and the circulating plasma concentration of angiotensin II (r = +0.60; P less than 0.05) was both significant and positive. By contrast, the total 'secretion' rate of angiotensin II by both kidneys was inversely related to arterial plasma angiotensin II (r = -0.92; P less than 0.001). This latter relationship suggests an important role for the kidney in clearing angiotensin II from the circulation, this being more marked the higher the arterial angiotensin II concentration.(ABSTRACT TRUNCATED AT 400 WORDS)     

单侧肾动脉狭窄患者肾静脉肾素活性的变化及意义

目的探讨动脉粥样硬化性肾动脉狭窄患者肾静脉肾素活性变化及其和介入治疗后血压变化的关系。方法测定50例单侧肾动脉明显狭窄(管腔狭窄≥70%)患者肾动脉支架置入前双侧肾静脉和外周静脉肾素活性及血管紧张素Ⅱ浓度,分析其与肾动脉狭窄及支架术后血压变化的关系。结果同时伴有冠状动脉狭窄的患者成功接受冠状动脉及肾动脉血运重建术。狭窄侧肾静脉肾素平均活性明显高于对侧[狭窄侧(1.44±1.73)ng·ml-1·h-1和对照侧(1.27±1.57)ng·ml-1·h-1,P=0.04],14例(28%)狭窄侧与对侧肾素活性比值≥1.5(肾血管性高血压组)。平均随访(12±9)个月,9例术后血压转为正常,其中肾血管性高血压组7例[50%,与对照组2例(6%)比较,P<0.001]。多因素回归分析表明肾素活性比值≥1·5与肾动脉支架术后高血压治愈相关(风险比值OR=3.15,95%CI为1.49~5.97,P=0.02)。结论约三分之一动脉粥样硬化性肾动脉狭窄患者狭窄侧肾静脉肾素分泌显著增加(≥对侧1.5倍),这些患者中半数高血压在肾动脉支架术后可以治愈。     

Reversible nephrotic syndrome due to high renin state in renovascular hypertension

Unilateral renal artery stenosis can lead to a non-functional kidney which secretes large amounts of renin. Four cases are presented in which the high renin state resulted in hypertension, proteinuria from the intact contralateral kidney, and secondary aldosteronism. The proteinuria was in the nephrotic range, which is unusual in renovascular hypertension, but gradually disappeared after correction of the high renin state by removal of the renin-secreting kidney or administration of an ACE inhibitor. Accordingly, when there is marked proteinuria in the presence of new-onset or rapidly progressive hypertension, hypokalaemic alkalosis, and a high peripheral PRA, renal artery stenosis should be considered since the proteinuria may be reversible after nephrectomy, repair of the ischaemic kidney or medical therapy.     

Renal protective effects of blocking the intrarenal renin-angiotensin system: angiotensin II type I receptor antagonist compared with angiotensin-converting enzyme inhibitor.

The present study compared renoprotective effects of angiotensin II type I receptor antagonist (AT1RA) with angiotensin converting enzyme inhibitor (ACEI), and their influence on the renin-angiotensin-system (RAS). Experimental nephrotic syndrome was induced in SD rats by repeated peritoneal injections of puromycin. Twenty-eight rats were randomly divided into four groups: normal control, nephrotic control, ACEI-treated, and AT1RA-treated groups. Serum, urine, and renal tissue were collected for study at the end of 12 weeks. Compared with those of the nephrotic control group, urinary protein was less and renal function was better in both treated groups. The glomerular and interstitial damage indexes of both ACEI- and AT1RA-treated rats were lower than those of nephrotic control rats, with no significant difference observed between the two treated groups. Local renal ACE activity and angiotensin II concentration were elevated in nephrotic rats (p< 0.01). However, there is no significant difference in circulating RAS, renal tissue renin, and aldosterone between the normal control and nephrotic control rats. As expected, enalapril inhibited the local renal ACE activity and significantly decreased angiotensin II (p< 0.01). Intrarenal ACE activity and angiotensin concentration returned to normal levels after treatment with irbesartan (p< 0.01). In conclusion, AT1RA and ACEI have comparable renal protective effects, and these protective effects were associated with the inhibition of intrarenal ANG II.     

Renin-angiotensin-aldosterone system and pulmonary hemodynamics in patients with pulmonary artery hypertension

To investigate the relationship between renin-angiotensin-aldosterone system and pulmonary hemodynamic parameters in patients with chronic pulmonary artery hypertension, we measured plasma levels of renin activity, angiotensin II and aldosterone in 11 patients during right heart catheterization. All patients had chronic obstructive pulmonary disease. At rest, plasma concentration of angiotensin II positively correlated with mean pulmonary artery pressure (r = 0.76, P less than 0.01) and pulmonary vascular resistance (r = 0.64, P less than 0.05). During exercise, plasma level of angiotensin II increased from 70 +/- 21 to 81 +/- 24 pg/ml (P less than 0.01) and plasma renin activity from 0.66 +/- 0.54 to 1.28 +/- 1.2 ng/ml/h (P less than 0.05), whereas mean pulmonary artery pressure increased from 3.73 +/- 0.85 to 6.27 +/- 1.81 kPa (28 +/- 6.4 to 47 +/- 13.6 mmHg). Increase of angiotensin II correlated with changes in mean pulmonary artery pressure (r = 0.69, P less than 0.05) but not with systemic artery pressure. The results of present study suggest that angiotensin II might play a role in the development of pulmonary artery hypertension in patients with chronic obstructive pulmonary disease.     

Intrarenal de novo production of angiotensin I in subjects with renal artery stenosis

To estimate the renal extraction and de novo production of angiotensin I and to assess the contribution of blood-borne renin to renal angiotensin I production, the aortic and renal venous plasma levels of renin and intact [125I]angiotensin I and endogenous angiotensin I during continuous systemic intravenous infusion of monoiodinated [125I]angiotensin I were measured in subjects with unilateral renal artery stenosis (n = 8) who were treated with captopril (50 mg b.i.d.). Results demonstrated that 80% of angiotensin I delivered by the renal artery was extracted both by the affected and the unaffected kidney and that on both sides a major part of angiotensin I in the renal vein was derived from intrarenal de novo production. Production of plasma angiotensin I was in excess over extraction (p less than 0.01) on the affected side, whereas extraction was in excess over production (p less than 0.01) on the contralateral side. The plasma level of de novo intrarenally produced angiotensin I in the renal vein was seven times higher on the affected side than the contralateral side. This difference was by far too big to be explained by a difference in the transit time of blood between the two kidneys, by an augmented production of angiotensin I in the circulating blood passing through the affected kidney due to the higher level of venous plasma renin activity in that kidney, or by the combination of both.(ABSTRACT TRUNCATED AT 250 WORDS)     

Responses of the stenosed and contralateral kidneys to [Sar1, Thr8] AII in human renovascular hypertension

To better define the intrarenal hemodynamic effects of angiotensin in human renovascular hypertension, 10 patients underwent renal hemodynamic and functional measurements before and during infusion of a competitive angiotensin analog, [Sar1, Thr8] AII. Eight had technically satisfactory split function studies. Despite a fall in mean arterial pressure (132 +/- 6 to 121 +/- 6 mm Hg, p less than 0.05) and humoral changes consistent with angiotensin-mediated hypertension, the intrarenal effects of this analog were commonly those of an angiotensin agonist, producing vasoconstriction and sodium retention. This was quantitatively greatest in the contralateral kidney, whose preinfusion sodium excretion (86 +/- 30 microEq/min vs 25 +/- 9 microEq/min, p less than 0.02) and glomerular filtration rate (76 +/- 7 ml/min vs 41 +/- 7 ml/min, p less than 0.01) were higher than the stenotic kidney. In some cases, an increase in renal blood flow and rise in sodium excretion were evident during angiotensin blockade, suggesting a tonic intrarenal action of angiotensin. Although renin vein renin values differed markedly between the stenotic and contralateral kidney (ratio = 2.05 +/- 0.30), relative changes in effective renal plasma flow were correlated (r = 0.84: p less than 0.01) during infusion of this analog. These results underscore the differences in sensitivities between vascular beds to the effects of angiotensin II and the major role of the contralateral kidney in renal function and sodium homeostasis in human renovascular hypertension.     

A case of nephrotic syndrome associated with renovascular hypertension successfully treated with candesartan.

A sixty eight-year-old man was referred to our hospital for evaluation of hypertension and hypokalemia. His chief complaints were fatigability and weakness of the lower extremities. Atrophy of the right kidney was noted on computed tomography. The laboratory findings demonstrated massive proteinuria, markedly elevated plasma renin activity, hypokalemia, and renal insufficiency. Angiography showed total occlusion of the right renal artery. The patient was diagnosed as having nephrotic syndrome associated with renovascular hypertension. Treatment with candesartan, an angiotensin-II-receptor blocker (ARB), controlled both hypertension and proteinuria satisfactorily without worsening of his renal function. This is the first report on the effect of ARB on nephrotic syndrome associated with renovascular hypertension. Based on the results, ARB can be considered a promising agent for the treatment of patients with renovascular hypertension with massive proteinuria and renal insufficiency.     

Sometimes when you hear hoof beats, it could be a zebra: consider the diagnosis of Fabry disease

Background

Conditions associated with high intraglomerular filtration pressure can cause secondary focal segmental glomerulosclerosis (FSGS). Unilateral renal artery stenosis (RAS) or its occlusion results in FSGS-like changes and the nephrotic syndrome in the contralateral kidney due to hyperfiltration. However, it has been rarely reported that stenosis of a renal arterial branch can result in FSGS-like changes in a different portion in the same kidney allograft.

Case presentation

A 60-year-old male kidney recipient developed allograft dysfunction after angiotensin II receptor blockade for hypertension 4?months after transplantation. It was proven that one of two arterial branches of the graft was markedly stenotic. Graft dysfunction improved after percutaneous transluminal arterioplasty (PTA), however; the stenosis recurred and massive proteinuria developed 5?months later. Graft biopsy showed ischemic changes in the region fed by the stenotic artery branch and in contrast FSGS-like changes in the region fed by the other branch. His clinicopathological manifestation including massive proteinuria almost normalized after the repeat PTA.

Conclusion

Here we report a case of secondary FSGS of a kidney allograft due to severe RAS of a branch of the same kidney, in which clinical and pathological improvement were confirmed after radiological intervention. When moderate to severe proteinuria appear, secondarily developed FSGS as well as primary (recurrent or de novo) FSGS should be taken into account in kidney transplant recipients.     

Inverse relation of exchangeable sodium and blood pressure in hypertensive patients with renal artery stenosis

Measurements of exchangeable sodium, arterial pressure and plasma concentrations of active renin, angiotensin II, aldosterone, sodium and potassium were made in 35 hypertensive patients with renal artery stenosis, 30 having unilateral renal arterial lesions. Plasma urea was below 7 mmol/l in 24 of the patients with unilateral lesions. In these and in the whole group of 35 patients there were significant inverse correlations between exchangeable sodium and diastolic blood pressure and between plasma sodium concentration and diastolic pressure. Six patients had hyponatraemia with a plasma sodium concentration less than 135 mmol/l. All were sodium-deplete with secondary hyperaldosteronism, three also having malignant-phase hypertension. Twelve of the patients with unilateral renal artery stenosis underwent bilateral ureteric catheterization. Sodium excretion was greater from the contralateral kidney than from the affected kidney and the rate of sodium excretion from the former, but not from the latter, was significantly related to arterial pressure. The relation of diastolic blood pressure and exchangeable sodium is the opposite of the positive correlation found in essential hypertension and Conn's syndrome. In renal artery stenosis the inverse correlation could result from a natriuretic effect of increased arterial pressure occurring mainly in the contralateral kidney.     

Effect of the angiotensin II blocker 1-Sar-8-Ala-angiotensin II on renal artery clip hypertension in the rat.

Twenty-four conscious male Wistar rats with hypertension induced by left renal artery clipping (two-kidney hypertension) were infused intravenously with 1-Sar-8-Ala-angiotensin II a competitive angiotensin II antagonist. The spectrum of responses was wide, ranging from a mild elevation in blood pressure to a marked fall in blood pressure, despite effective and specific angiotensin blockade in all cases. The change in blood pressure during 1-Sar-8-Ala-AII infusion activity showed a significant correlation with the level of plasma renin prevailing immediately before the infusion (r = - 0.78, P less than 0.01) but not with the prevailing blood urea level (r = 0.27, 0.1 greater than P greater than 0.05), the drgree of hypertension (r = 0.42, 0.1 greater than P greater than 0.05), or the time since clipping (r = 0.02, P greater than 0.05). There was no significant correlation between the degree of hypertension and the plasma renin activity (r = 0.42, 0.1 greater than P greater than 0.05). In rats with blood pressure drops greater than 20 mm Hg in response to 1-Sar-8-Ala-AII, the final blood pressure level was still above the normotensive range. Excision of the clipped kidney reduced blood pressure to normal or to near normal within 24 hours in all of the rats tested. It is concluded that the degree of dependence of renal hypertension on the renin-angiotensin system is directly related to the increase in circulating angiotensin itself and not to an increase in sensitivity to angiotensin. Other factors appear to be involved in renal clip hypertension in addition to circulating renin and angiotensin, especially when the measured activity of plasma renin is normal.     

Cadmium and renal hypertension

In our study we investigated 36 patients with renal disease, 22 of whom were hypertensive. In all proteinuria was present (4.30 +/- 5.05 g protein/day) and renal lesions were proved by renal biopsy. Blood cadmium in non-smokers was significantly (P less than 0.05) lower than in smokers. We found a positive correlation between cadmium concentrations in blood and urine (P less than 0.01, r = 0.44) and between cadmium concentration in blood and serum uric acid levels (P less than 0.01, r = 0.44). Proteinuria was weakly correlated with cadmium concentration in urine (P less than 0.05, r = 0.35). Patients with hypertension showed a significantly higher (P less than 0.05) urine cadmium excretion per day (1.60 +/- 1.12 micrograms/day compared with normotensives with disease of the kidney (1.14 +/- 1.47 micrograms/day). Our results indicate that cadmium may be involved in the development of hypertension in patients with renal disease.     

Renal handling of angiotensins I and II in patients with renovascular hypertension

Plasma renin (PRC) and angiotensin I (pANG I) and II (pANG II) concentrations were determined at renal vein catheterization in 38 hypertensive patients suspected of renal or renovascular aetiology. Veno-arterial differences in pANG I across the affected kidney in patients with lateralization of the renin secretion indicated release of angiotensin I (ANG I) in considerable amounts. Veno-arterial differences in pANG II of around zero indicated that generation and elimination of angiotensin II (ANG II) were equal in that kidney. Across the contralateral kidney the veno-arterial differences in PRC and pANG II were both close to zero, while negative differences in pANG II indicated the removal of ANG II. In patients without lateralization of the renin secretion the veno-arterial differences in pANG I were close to zero or positive, those of pANG II being close to zero or negative. In 14 of the 38 patients, data were obtained either during maintenance treatment with captopril or after a single dose of this converting enzyme inhibitor. Systemic PRC and pANG I values were extremely high and pANG II values low. The pANG I gradient across the affected kidney was further increased compared with pre-captopril levels, whereas the contralateral kidney still eliminated ANG I.     

Effect of telmisartan on blood pressure control and kidney function in hypertensive, proteinuric patients with chronic kidney disease

OBJECTIVES: To assess the antihypertensive and antiproteinuric efficacy and safety of the angiotensin II type 1 receptor blocker telmisartan in patients with hypertension and chronic kidney disease. METHODS: A multicenter, prospective trial was performed in adults with hypertension [systolic blood pressure (SBP)/diastolic blood pressure (DBP) >130/85 mmHg), chronic renal insufficiency (serum creatinine <4.0 mg/dl), and proteinuria (>1 g/24 h). In addition to existing antihypertensive therapy, the nature and doses of which remained unchanged throughout the study, patients received once-daily telmisartan 40 mg for the first 3 months followed by forced titration to telmisartan 80 mg for the subsequent 3 months to achieve a target SBP/DBP of <130/85 mmHg. The rationale for using telmisartan was its long half-life efficacy, greater antihypertensive effect compared with valsartan or losartan, and newly discovered potential antidiabetic effect. RESULTS: The study was conducted in 92 patients (45 men, 47 women), of whom 60 had diabetes mellitus (54 patients with type 2 disease). Five patients discontinued prematurely: two because of hyperkalemia, two because of protocol violation, and one because of lack of efficacy. After 6 months' telmisartan treatment, office trough seated SBP was reduced by 19.6 mmHg (P<0.001) from 154.9+/-14.6 mmHg and DBP by 11.8 mmHg (P<0.001) from 91.7+/-8.1 mmHg. Seated trough SBP/DBP of <130/85 mmHg was achieved at 6 months in 34.8% of patients. Ambulatory blood pressure monitoring also demonstrated significant reductions in mean daytime SBP of 10.9 mmHg (P=0.01), night-time SBP of 12.1 mmHg (P=0.05), daytime DBP of 3.1 mmHg (P=0.05), and night-time DBP of 6.5 mmHg (P=0.05). Proteinuria decreased significantly from 3.6+/-3.4 to 2.8+/-2.8 g/24 h (P=0.01). A decrease in proteinuria depended significantly on a decrease in SBP at the end of the study (P=0.044). Each decrease in SBP of about 10 mmHg led to a decrease in proteinuria of about 0.79 g/24 h (95% CI 0.02-1.56 g/24 h). Serum creatinine increased from 1.96+/-0.79 to 2.08+/-0.89 mg/dl (P=0.01), whereas creatinine clearance did not change significantly. CONCLUSIONS: Telmisartan effectively and safely reduced blood pressure and brought about regression of proteinuria in diabetic and nondiabetic, hypertensive, proteinuric patients with chronic kidney disease, even in those with mild-to-moderate chronic renal failure.     

Concentration and molecular forms of active and inactive renin in human fetal kidney, amniotic fluid and adrenal gland: evidence for renin-angiotensin system hyperactivity in 2nd trimester of pregnancy

In a study of 38 fetuses total kidney renin was significantly correlated with gestational age (r = 0.63). Although whole fetal kidney renin specific activity was found to decrease with gestational age (r = -0.65), the mean value of the specific activity was about 20 times greater than in normal adult cortex and double that in tissue from patients with renal artery stenosis, suggesting renin-angiotensin system hyperactivity. In approximately 40% of fetal kidneys examined, evidence for an inactive (trypsin-activatable) renin precursor was found. The molecular weight of this form was indistinguishable from active renin (45 000 daltons) by Sephadex chromatography. Amniotic fluid from nine cases (100%) contained angiotensin (ANG) 1, angiotensin converting enzyme (ACE), renin substrate, active and inactive renin (both 45 000 daltons). Five of the 38 (13%) fetal adrenal glands contained renin, but no evidence for trypsin-activatable forms. Aldosterone was present in low concentration in the earliest adrenals examined, and a positive correlation existed between total tissue aldosterone and gestational age (r = 0.73). These findings suggest that the fetal renin-angiotensin system has an important role to play in the maintenance of extracellular fluid volume and blood pressure in the developing fetus.     

Renal blood flow and its response to angiotensin II. An interaction between oral contraceptive agents, sodium intake, and the renin-angiotensin system in healthy young women.

A variety of estrogen- and progestin-containing oral contraceptive agents reduced renal blood flow (RBF) significantly in 23 healthy, nonhypertensive young women, to a mean of 75 +/- 3.3% of the value expected for their age and dietary sodium intake (P less than 0.001). There was also significant activation of the renin-angiotensin system: renin substrate was increased approximately 3-fold in association with a striking increase in the circulating renin activity and angiotensin II levels in relation to sodium intake and excretion. Two observations suggest that the RBF reduction was directly mediated by angiotensin II. A correlation was demonstrable between circulating angiotensin II and RBF (P less than 0.01), and renal vascular responsiveness to angiotensin II infused into the renal artery was reduced significantly (P less than 0.001). Moreover, the oral contraceptive agents modified the basic relationship between sodium balance and vascular responsiveness to angiotensin II, suggesting that the agents acted through some mechanism other than alteration in the state of sodium balance. These observations provide further evidence for an important role of angiotensin II as a determinant of RBF. Renal vasoconstriction may contribute to the genesis of a number of complications, such as sodium retention and hypertension, associated with oral contraceptive use.     

Assessment of renal artery stenosis severity by pressure gradient measurements.

OBJECTIVES: The purpose of this study was to define "significant" renal artery stenosis (i.e., a stenosis able to induce arterial hypertension). BACKGROUND: The degree of renal artery stenosis that justifies an attempt at revascularization is unknown. METHODS: In 15 patients, transstenotic pressure measurements were obtained before and after unilateral stenting. After stenting, graded stenoses were created in the stented segment by progressive inflation of a balloon catheter. Stenosis severity was expressed as the ratio of distal pressure (P(d)) corrected for aortic pressure (P(a)). Balloon inflation pressure was adjusted to create 6 degrees of stenosis (P(d)/P(a) from 1.0 to 0.5, each step during 10 min). Plasma renin concentration was measured at the end of each step in the aorta and in both renal veins. RESULTS: For a P(d)/P(a) ratio >0.90, no significant change in plasma renin concentration was observed. However, when P(d)/P(a) became <0.90, a significant increase in renin was observed in the renal vein of the stenotic kidney, finally reaching a maximal increase of 346 +/- 145% for P(d)/P(a) of 0.50 (p = 0.006). These values returned to baseline when the stenosis was relieved. In addition, plasma renin concentration increased significantly in the vein from the non-stenotic kidney (p = 0.02). CONCLUSIONS: In renal artery stenoses, a P(d)/P(a) ratio of 0.90 can be considered a threshold value below which the stenosis is likely responsible for an up-regulation of renin production and, thus, for renovascular hypertension. These findings might contribute to better patient selection for renal angioplasty.     

The effect of chronic prazosin therapy on the response of the renin-angiotensin system in patients with essential hypertension

Changes in plasma active and inactive renin and angiotensin II in response to tilt and intravenous frusemide were assessed in ten patients with essential hypertension, before treatment and again during chronic therapy with the alpha 1-adrenoceptor antagonist prazosin. During prazosin treatment blood pressure in the patients fell from mean levels 172/108 mmHg to 149/88 mmHg (P less than 0.05). Both before and during prazosin, tilt and frusemide each led to significant elevation of plasma active renin (P less than 0.001) and angiotensin II (P less than 0.05). Inactive renin tended to fall with tilt, and fell significantly following frusemide (P less than 0.05). Active renin (P less than 0.05) and angiotensin II (P less than 0.01) were lower 15 hours after dosing during chronic prazosin therapy than before treatment, but changes after tilt and frusemide were not attenuated during treatment. Chronic prazosin administration does not appear substantially to affect changes in active renin or angiotensin II in response to two standard stimuli, and may be useful in controlling hypertensive patients pending investigation of their renin-angiotensin system.     

Adenosine causes the release of active renin and angiotensin II in the coronary circulation of patients with essential hypertension.

OBJECTIVES: The aim of the study was to evaluate whether adenosine infusion can induce production of active renin and angiotensin II in human coronary circulation. BACKGROUND: Adenosine can activate angiotensin production in the forearm vessels of essential hypertensive patients. METHODS: In six normotensive subjects and 12 essential hypertensive patients adenosine was infused into the left anterior descending coronary artery (1, 10, 100 and 1,000 microg/min x 5 min each) while active renin (radioimmunometric assay) and angiotensin II (radioimmunoassay after high performance liquid chromatography purification) were measured in venous (great cardiac vein) and coronary arterial blood samples. In five out of 12 hypertensive patients adenosine infusion and plasma samples were repeated during intracoronary angiotensin-converting enzyme inhibitor benazeprilat (25 microg/min) administration. Finally, in adjunctive hypertensive patients, the same procedure was applied during intracoronary sodium nitroprusside (n = 4) or acetylcholine (n = 4). RESULTS: In hypertensive patients, but not in control subjects, despite a similar increment in coronary blood flow, a significant (p < 0.05) transient increase of venous active renin (from 10.7 +/- 1.4 [95% confidence interval 9.4 to 11.8] to a maximum of 13.8 +/- 2.1 [12.2 to 15.5] with a consequent drop to 10.9 +/- 1.8 [9.7 to 12.1] pg/ml), and angiotensin II (from 14.6 +/- 2.0 [12.7 to 16.5] to a maximum of 20.4 +/- 2.7 [18.7 to 22.2] with a consequent drop to 16.3 +/- 1.8 [13.9 to 18.7] pg/ml) was observed under adenosine infusion, whereas arterial values did not change. Calculated venous-arterial active renin and angiotensin II release showed a strong correlation (r = 0.78 and r = 0.71, respectively; p < 0.001) with circulating active renin. This adenosine-induced venous angiotensin II increase was significantly blunted by benazeprilat. Finally, both sodium nitroprusside and acetylcholine did not affect arterial and venous values of active renin and angiotensin II. CONCLUSIONS: These data indicate that exogenous adenosine stimulates the release of active renin and angiotensin II in the coronary arteries of essential hypertensive patients, and suggest that this phenomenon is probably due to renin release from tissue stores of renally derived renin.     

Clinical implications of increased plasma angiotensin II despite ACE inhibitor therapy in patients with congestive heart failure.

AIMS: The aim of the study was to assess the incidence and clinical implications of increased plasma angiotensin II despite chronic ACE inhibitor therapy in patients with heart failure. METHODS AND RESULTS: The studied population consisted of 70 patients (mean age 59+/-9 years). Plasma renin activity and plasma concentration of aldosterone, norepinephrine, atrial natriuretic peptide, angiotensin II, tumour necrosis factor, interleukin-6 and interleukin-1B were assessed at 6 months of ACE inhibitor therapy. Mean left ventricular ejection fraction was 24+/-5% and the end-systolic and end-diastolic diameters were 59+/-9 and 71+/-8 mm, respectively. Despite chronic enalapril or captopril therapy, 35 patients (50%) had increased plasma angiotensin II (median 33 pg. ml(-1), range 17-84), while it was in the normal range in the remaining 35 patients (median 10 pg. ml(-1), range 5-15). Plasma renin activity (P=0.005), interleukin-6 (P=0.004), New York Heart Association functional class III-IV (P=0. 006), furosemide dose (P=0.01), lack of beta-blocker therapy (P=0. 04) and norepinephrine (P=0.04) were univariately associated with increased angiotensin II. Multivariate regression analysis identified the plasma renin activity (0.0004), norepinephrine (0.02) and interleukin-6 (0.03) as independent predictors of plasma angiotensin II. During follow-up (35+/-29 months), nine (12.8%) patients died and 13 had new heart failure episodes. Increased plasma angiotensin II, despite ACE inhibitor therapy, was a significant predictor of death or heart failure according to the Kaplan-Meier survival method by log rank test (P=0.002). CONCLUSION: Fifty per cent of patients with heart failure, ha increased plasma angiotension II despite chronic ACE inhibitor therapy. These patients had higher neurohormonal activation and poor prognosis.