Renal vein renin in essential hypertension.

A frequency distribution curve and interval percentages of variations in right versus left renal vein renin (RVR) were calculated from 227 sets of renin data from patients with mild and moderate essential hypertension (EH). A renal vein renin ratio (RVRR), large/small, of approximately 2.0 or more falls beyond the 95 per cent confidence interval, and may therefore by considered to be abnormal. Although assay variability and sampling errors may contribute to artifactually large RVRR's in EH, they usually indicate true disparity, probably secondary to asymmetrical nephrosclerosis. Recent hypotheses regarding diagnostic value of RVR in hypertension are evaluated in light of data yielded by this investigation. Simultaneous and/or replicate sampling should reduced within-patient variability and improve clinical interpretation of test results.     

低肾素型原发性高血压尿液水通道蛋白-2水平的研究

目的 探讨低肾素型原发性高血压痛(LRH)患者尿液水孔蛋白-2(AQP-2)水平及其与血压之间的关系,并评价其对LRH的诊断价值.方法 根据血浆肾素活性将150例原发性高血压病患者分为LRH、正常肾素型和高肾素型3组,28例正常血压者作为对照组.采用酶联免疫吸附试验检测尿液AQP-2含量,用放射免疫分析法同步测定血浆血管加压素(AVP)水平.结果 LRH患者AQP-2、AVP水平均明显高于正常肾素型与高肾素型及对照组,分别为(77.6±12.4)nmol/L vs(50.0±10.9)nmol/L、(44.6±14.0)nmol/L、(45.5±11.8)nmol/L,均P<0.01;(5.39±1.55)ng/L vs(3.82±1.51)ng/L、(3.24±1.01)ng/L、(3.60±1.28)ng/L,均P<0.01.AQP-2与AVP、平均动脉压正相关(Rs=0.334,P=0.016;Rs=0.391,P=0.004),与血浆肾素活性负相关(Rs=-0.285,P=0.040),并且AQP-2水平随高血压分级增高而升高(68.3±17.5)nmol/L、(76.7±10.8)nmol/L、(83.4±12.7)nmol/L,F=6.64,P=0.003;多元线性回归显示AQP.2与LRH患者平均动脉压显著相关.以对照组尿液AQP-2含量(x 1.96 s)为标准,AQP-2诊断LRH的敏感度、特异度、阳性预测值及阴性预测值分别为90.4%、94.9%、90.4%、94.9%.结论 LRH患者尿液AQP-2水平升高与血压相关,并且其对LRH有一定诊断价值.     

Plasma renin activity in essential hypertension

Summary A study of the frequency distribution of plasma renin activity (PRA) in 123 patients with essential hypertension (EH) produced no evidence of a distinct subpopulation with low renin levels, whether the samples were taken from supine or upright patients. Applying an arbitraty classification criterion, however, low PRA levels were found in 30.1% of patients. There were no significant differences in mean blood pressure, 24-h sodium excretion, and age when groups with low, normal or high PRA levels were compared. The incidence of PRA hyporesponsiveness was similar in the three groups of patients, but increased with age. In the female there was a preponderance of low PRA levels. It is concluded that EH with low PRA levels is not a separate diagnostic entity and, when PRA is low in a hypertensive subject, the possible effects of age, blood pressure, and sex ought to be taken into account before other causes of low PRA are postulated.     

Renal haemodynamics and plasma renin in patients with essential hypertension.

1. Blood pressure, glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in twenty-three patients with essential hypertension and in twenty-one control subjects. Plasma renin concentration was measured in all the hypertensive patients and in fifteen control subjects. 2. GFR and RPF were similar in the hypertensive group and in the control group, whereas the renal vascular resistance was significantly higher in the hypertensive patients. GFR and RPF decreased with increasing blood pressure in both groups. Increasing age induced a further reduction in GFR and RPF in the control subjects but not in the hypertensive patients. 3. Plasma renin concentration in the hypertensive group did not differ from that in the control subjects. The concentration was not correlated to age in either the hypertensive or normal group. 4. Plasma renin index was positively correlated to GFR and RPF and inversely correlated to filtration fraction and renal vascular resistance. 5. It is concluded that GFR and RPF depend on blood pressure in both hypertensive patients and normotensive control subjects. In contrast to the control group, the age effect was negligible in the hypertensive group. It is suggested that renin release depends on changes in renal vascular resistance in the arterioles at the glomerulus and the results support the baroreceptor theory of renin release.     

Change in plasma renin activity by cold storage of plasma in normal subjects and patients with essential hypertension and primary aldosteronism.

The time courses of change in renin activity after cold storage of human plasma at -5 degrees C and pH 7.4 were examined in 5 normal subjects, 6 patients with essential hypertension and one female patient with primary aldosteronism before and after extirpation of the adrenal tumor. In the 5 normal subjects and 6 essential hypertensives, the gradual increase in plasma renin activity was observed until 10 days of cold storage. The same result was obtained in the case of primary aldosteronism. However, there was no increase in renin activity despite of cold storage for 10 days in plasma which was sampled from this patient 45 days after operation. These data indicate that a period of 4 days for cryoactivation of human plasma renin as has been reported by Sealey et al. is not sufficient to accomplish activation of renin by cold storage.     

Plasma catecholamines and renin activity in response to exercise in patients with essential hypertension.

1. The effect of physical exercise on blood pressure, plasma catecholamines and plasma renin activity was studied in fourteen patients with essential hypertension and in eight healthy subjects. 2. Resting plasma noradrenaline and adrenaline and plasma renin activity of the hypertensive patients did not differ from those of the control subjects. 3. In response to graded exercise producing successive heart rates of 120, 140 and 160 beats/min, significantly greater increases of blood pressure were found in the patients than in the control subjects. 4. Plasma noradrenaline increased significantly in both groups at all levels of exercise, the responses being significantly greater in the hypertensive patients. 5. The mean arterial blood pressure was significantly correlated with plasma noradrenaline concentration in the control subjects but not in the hypertensive patients. 6. In the hypertensive group plasma adrenaline increased significantly after exercise at all work loads whereas, in the control group, significant increase occurred only at the highest work load. The differences in the response of the two groups were significant at each work load. 7. Plasma renin activity increased significantly after exercise at the heart rate of 120 beats/min, both in the hypertensive patients and in the control subjects. The magnitude of the response was similar in the two groups.     

The effect of pindolol on plasma renin activity in patients with essential hypertension

Twenty-two patients with essential hypertension were treated for 3 months with pindolol, and blood pressure and plasma renin activity were measured at rest and after stimulation (upright posture stimulation and insulin induced hypoglycaemia stimulation). Beta-receptor blockade produced a significant decrease in systolic and diastolic blood pressure. After treatment with pindolol the plasma renin activity was significantly lower. Under conditions of renin stimulation such as orthostasis and insulin produced hypoglycaemia, plasma renin activity was significantly lower in treated patients. There was no correlation between the fall of plasma renin activity and the decrease of blood pressure. Renin suppression is probably only one of the factors involved in the reduction in the blood pressure in these patients.     

Kidney and plasma renin in human renovascular hypertension.

Renin activities were determined in plasma and in single, microdissected juxtaglomerular apparatus in 19 patients with unilateral renal artery stenosis. The mean juxtaglomerular apparatus renin concentration in the stenosed kidneys was 5.5 +/- 1.2 (SEM) mug.l-1.h-1 which is about ten times that of the suppressed renin concentration in the contralateral kidneys (0.6 +/- 0.05 mug.l-1.h-1). On the affected side a positive correlation was found between intrarenal and renal venous renin concentration (r = 0.93; p less than 0.001). Both intrarenal and renal venous renin concentrations of the stenosed kindeys were positively correlated to renin secretion rates, as calculated from renin analysis in plasma from the vena cava and renal veins. No relationship could be demonstrated between intrarenal or renal venous renin concentration and the degree of blood pressure elevation or transstenotic pressure gradient. However, a positive correlation was evident between peripheral plasma renin activity and diastolic blood pressure (r = 0.88; p less than 0.001). Comparative enzyme kinetic analyses of renin from the juxtaglomerular apparatus and renal venous plasma were performed using sheep substrate. The lowest apparent Km-values of renin were found in renal venous plasma from the stenosed kidneys (198 +/- 13 mug/l) compared with the contralateral side (301 +/- 20 mug/l; p less than 0.001). Mean apparent Km-values of juxtaglomerular apparatus renin in the stenosed (270 +/- 36 mug/l) and contralateral (292 +/- 37 mug/l) kidneys did not differ. No significant differences were found between mean apparent Km-values for renin in peripheral plasma of renovascular hypertensive patients and control subjects using either homologous human or heterologous sheep renin substrate. The results suggest that, in addition to the renin concentration other factors are relevant to chronic high blood pressure in renovascular hypertension.     

Long-term ambulatory follow-up of hypertension patients with low renin activity in blood

AIM: To characterize a clinical course of arterial hypertension in patients with low activity of blood renin. MATERIAL AND METHODS: 44 hypertensive patients with low activity of blood renin participated in the trial. They were divided into three groups consisting of 18, 14 and 12 patients (group 1, 2 and 3 with adrenal adenoma, adrenal hyperplasia and hypertension, respectively). RESULTS: Baseline hypertension was higher in group 1. The clinical picture did not differ much between the groups. Long-term follow-up has revealed that mean arterial pressure tended to lowering in groups 1 and 2 while in group 3 it tended to rise. Incidence of arrhythmia increased thrice though myasthenia became less frequent. CONCLUSION: Group 1 patients had a more severe clinical course of hypertension with high lethality and many associated diseases. To achieve a clinical effect, they had to take higher doses of antihypertensive drugs.     

131I]Hippuran renography in normal subjects and in patients with essential hypertension.

Seventeen normal subjects and 21 patients with essential hypertension were examined by [131I]hippuran renography. Both groups were studied twice on the same day, first in a state of moderate dehydration and then after rehydration. From these data, four sets of reference intervals were established for several renographic parameters. Differences between the two groups were defined. The most impressive observation was a greater functional disparity between the two kidneys of one individual in the group of hypertensive patients, particularly when in a state of moderate volume depletion. This was reflected in a greater variance of certain kidney-to-kidney ratios derived from the renographic tracings. This article presents basic data to be utilized in clinical renography, as described in an accompanying article.     

Guanabenz in essential hypertension.

Fifty-five patients with mild to moderately severe essential hypertension were treated with guanabenz (2, 6-dichlorobenzylidene aminoguanidine acetate) in doses from 4 to 16 mg twice daily in a randomized, placebo-controlled study. The patients treated with placebo in the initial phase of the study were subsequently treated with guanabenz. The mean arterial pressure in the guanabenz group decreased from 130.6 to 107.6; that in the placebo group decreased from 129.6 to 126.6 standing and from 126.6 tp 109.9 and 128.8 to 120.5, respectively, supine. The principle adverse effects included sedation, dry mouth, weakness, and tiredness. Of the guanabenz-treated patients 84% had sustained decrease in supine diastolic blood pressure of 10 mm Hg or more, whereas in the placebo-treated patients only 32% had such a response. There was no significant orthostatic hypotension. Guanabenz thus appears to be an effective antihypertensive drug in patients with mild to moderately severe hypertension.     

Plasma renin activity in patients with renovascular hypertension.

Plasma renin activity (PRA) in peripheral and renal vein blood was determined in 25 patients with renovascular hypertension. Significant elevation of resting peripheral vein PRA was observed in only 9 (36%) of them. 11 (61%) out of 18 patients whose conditions were improved by surgery had shown normal levels of resting peripheral vein PRA preoperatively. Provocation test for renin secretion was done in 20 patients. 10 patients showed a hyper-response. 7 out of 15 patients who benefited from surgery had shown no response in PRA on the stimulation. Renal vein PRA was determined in 23 patients. In 16 significantly higher renal vein PRA was found on the affected side. However, measurement of renal vein PRA failed to predict the surgical results in one-third of the patients. Postoperative PRA and blood pressure were followed serially in 10 patients. PRA became normal within 3 days postoperatively in 9 patients. While the normalization of blood pressure following operation was more rapid in 3 revascularized patients than in 7 nephrectomized, the normalization of PRA was quicker in the latter patients than in the former. These data indicate that measurement of PRA in peripheral and renal vein is not an infallible mean to determine the functional significance of renal arterial lesions.