Search PubMed⌕ Search

Biomedical subjects

R F Bing

Publications and source records attributed to R F Bing.

At least 91 records · Page 5Linked to original sources
PubMed1981

Plasma and interstitial volumes in essential hypertension: relationship to blood pressure.

1. Plasma and interstitial fluid volumes have been measured simultaneously in men with uncomplicated and untreated essential hypertension. 2. Plasma volume (Evans blue) was reduced in essential hypertension and correlated inversely with blood pressure. 3. Interstitial fluid volume, derived from bromine space and plasma volume, was also reduced in essential hypertension and correlated inversely with blood pressure. The mean reduction in both plasma and interstitial fluid volumes was 6-7%. 4. There is no evidence for volume expansion in essential hypertension and the relationship between plasma and interstitial fluid volumes is preserved. The contraction of plasma and interstitial fluid volumes is most likely to reflect a natriuresis and diuresis secondary to the raised renal perfusion pressure, and sodium retention is unlikely to be a primary event in essential hypertension.

Adult↗
PubMed1981

Haemodynamic changes after surgical reversal of chronic two-kidney, one-clip hypertension in the rat.

1. Within 24 h of surgical reversal of chronic Goldblatt two-kidney, one-clip hypertension in the rat, of greater than 4 months duration, blood pressure had fallen to normal levels. At this time there was no difference between the effects of removal of the clip or the ischaemic kidney but, at 60 days after reversal, the blood pressure of rats which had been nephrectomized was significantly higher than that of normal controls. 2. The fall in blood pressure was associated with a fall in total peripheral resistance to normal by 24 h despite the previous established fact that structural vascular changes take much longer to reverse. There was a corresponding rise in cardiac output, mainly due to an increase in stroke volume. Nephrectomized rats had a significantly higher stroke volume compared with those unclipped 24 h after operation. 3. As blood pressure can become normal in the presence of structural cardiovascular change by a fall in total peripheral resistance it would seem unlikely that resistance vessel hypertrophy is responsible for the maintenance of blood pressure in this model. Another peripherally acting mechanism therefore has to be postulated.

Animals↗
PubMed1981

Chemical renal medullectomy; effect upon reversal of two-kidney, one-clip hypertension in the rat.

1. Chemical renal medullectomy was produced in rats by injection of 2-bromoethylamine hydrobromide. Plasma creatinine and blood pressure were unchanged although urine volume was increased fourfold. 2. Left renal artery constriction resulted in similar degrees of hypertension in both intact and medullectomized rats. This was associated with a significantly smaller rise in plasma renin concentration in the latter. 3. Blood pressure in conscious intact hypertensive rats became normal within 24 h of unclipping whereas blood pressure of medullectomized rats remained significantly elevated. 4. The presence of an intact renal medulla is essential to the complete reversal of two-kidney, one-clip hypertension in the rat. This may reflect the loss of a medullary vasodepressor system.

Animals↗
PubMed1981

Indapamide and bendrofluazide: a comparison in the management of essential hypertension.

1 To compare the efficacy of indapamide with that of bendrofluazide a randomised trial was carried out in twenty patients with essential hypertension. 2 Indapamide (2.5 mg a day) and bendrofluazide (5 mg a day) produced a significant but equivalent fall in blood pressure. 3 Both drugs caused a reduction in body weight and serum potassium with a rise in plasma renin activity but there were no other major side effects. 4 In twelve patients treated with a combination of indapamide and bendrofluazide there was no additional fall in mean blood pressure or serum potassium compared to treatment with bendrofluazide or indapamide alone.

Adult↗
PubMed1981

Effect of 12-hour infusions of saralasin or captopril on blood pressure in hypertensive conscious rats. Relationship to plasma renin, duration of hypertension, and effect of unclipping.

Saralasin (Sar1, Ala8 angiotensin II), a competitive antagonist of angiotensin II, or captopril, an angiotensin-converting enzyme inhibitor, were infused for 12 hr into conscious rats with Goldblatt two-kidney one-clip hypertension at an early stage (mean interval from clipping 36 days) and a chronic stage (151 days). In the early phase infusions of either saralasin or captopril produced a significant fall in blood pressure, which was maximal at 30 min, although the majority of animals remained hypertensive. In the chronic phase, saralasin produced a small and nonsignificant fall in blood pressure, whereas captopril produced a fall similar to that observed in the early group. No further fall in blood pressure was seen over the 12 hr period. PRC was markedly elevated in the early phase but did not differ significantly from normal in the chronic phase. The blood pressure fall produced by saralasin was significantly correlated with preinfusion PRC (r = 0.72 for the early group and 0.81 for the chronic group; p less than 0.01), whereas the fall in blood pressure produced by captopril was poorly correlated with PRC (r = 0.04 and 0.14, respectively). Captopril produced a minor fall and saralasin a minor elevation of blood 3 pressure in normal animals. Infusions of dextrose without inhibitor caused no change in blood pressure. Removal of the renal artery clip normalized blood pressure in the majority (88%) of animals in either the early or chronic phases. It is concluded that 12 hr infusions of these inhibitors are no more effective than 30 min infusions and do not fully correct hypertension in this model. Furthermore, the greater vasodepressor effect of captopril compared to saralasin in chronic hypertensive animals and the lack of correlation between PRC and change in blood pressure with captopril suggest that this agent has an action independent from blockade of the renin-angiotensin system. Removal of the renal artery clip is more effective than renin-angiotensin blockade in correcting Goldblatt two-kidney one-clip hypertension.

Angiotensin II↗
PubMed1981

Pulmonary edema.

Explore the source record for details and available documents.

Adult↗
PubMed1980

Hydralazine-induced systemic lupus erythematosus: influence of HLA-DR and sex on susceptibility.

26 patients with systemic lupus erythematosus (SLE) induced by treatment with the antihypertensive drug hydralazine were investigated to determine if predisposition to the toxic effect was associated with an HLA-DR antigen. 25 of the 26 patients were slow acetylators. The group was compared with three others (1) 113 healthy subjects, untested for acetylator phenotype, (2) 16 slow-acetylator hypertensive patients treated with hydralazine for more than a year without developing SLE, and (3) 20 patients with idiopathic SLE. The frequency of HLA-DR4 (73%) was significantly higher in the group with hydralazine-induced SLE than in the other groups (respectively 33%, 25%, and 25%). The ratio of women to men affected was 4:1. If the slow acetylators treated with hydralazine were analysed as one group, it was observed that all women with DR4 developed hydralazine-induced SLE; the only men to do so were those with DR2 who were receiving 200 mg hydralazine per day. These observations have led us to suggest guide lines for hydralazine therapy and point to a striking association between an HLA-DR antigen and an adverse reaction to a therapeutic agent. It was also noted that the distribution of DR antigens in the hydralazine-SLE patients was significantly different from that in the group with idiopathic SLE. This supports the view that the syndromes are separate entities.

Acetylation↗
PubMed1980

Vasodepressor property of the converting enzyme inhibitor captopril (SQ 14 225): the role of factors other than renin-angiotensin blockade in the rat.

1. The peptide converting enzyme inhibitor captopril was given (1.25 mg/kg intravenously) to normal and nephrectomized rats and rats with renovascular and deoxycorticosterone hypertension. 2. Captopril lowered blood pressure to a small extent in normal and nephrectomized rats. Bradykinin infusion in nephrectomized animals, however, potentiated the vasodepressor action of captopril. 3. Captopril produced a major blood pressure fall in the early stages of Goldblatt two-kidney one-clip hypertension: even when hypertension had been present for more than 4 months, a substantial vasodepressor action was seen. Rats with deoxycorticosterone-induced hypertension also showed a significant blood pressure fall. 4. Captopril was given to salt-loaded and salt-depleted rats in which the renin-angiotensin system had been blocked by infusion of the competitive angiotensin II antagonist saralasin. Captopril still lowered blood pressure in the salt-depleted group. 5. Captopril lowers blood pressure in situations where the renin-angiotensin system is not responsible for blood pressure maintenance. Further, the fall in blood pressure produced in Goldblatt two-kidney one-clip hypertension is greater than would be predicted on the basis of renin-angiotensin blockade. It is likely therefore that captopril lowers blood pressure by an action additional to angiotensin blockade. Bradykinin potentiation is one possible mechanism by which this may take place.

Angiotensin II↗
PubMed1980

Response of chronic renovascular hypertension to surgical correction or prolonged blockade of the renin-angiotensin system by two inhibitors in the rat.

1. Removal of the renal artery constriction but not of the clipped kidney restored the blood pressure to normal levels in Goldblatt two-kidney rats with hypertension of more than 4 months' duration. 2. Despite the differences in blood pressure response, both surgical procedures lowered plasma renin concentration to normal or below normal values. 3. Administration of the oral converting enzyme inhibitor SQ 14 225 produced a marked fall in blood pressure in Goldblatt kidney rats with chronic hypertension. However, a prolonged infusion of the angiotensin II antagonist saralasin was quite ineffective. The difference in response to the two inhibitors may have been due to bradykinin potentiation by the converting enzyme inhibitor. 4. Although plasma renin is often elevated in Goldblatt two-kidney rats with hypertension of more than 4 months' duration, the renin-angiotensin system plays no role in the maintenance of blood pressure at this stage.

Angiotensin II↗
PubMed1980

Reversible hypertension and hypothyroidism.

Six patients with hypothyroidism and hypertension whose blood pressure fell to normal when treated with thyroxine (172 +/- 7.2/112 +/- 2.1 to 140 +/- 3.2/84+/- 1.6 mmHg, P < 0.001) are described. Plasma renin activity (1.76 +/- 0.63 ng angiotensin I.ml-1.h-1) was low before treatment. Hypertension with low plasma renin is consistent with sodium retention. Hypertension in the hypothyroid patient only requires further evaluation if it persists after adequate treatment with thyroxine.

Adult↗
PubMed1980

Surgical correction of renovascular hypertension: dissociation between post-operative changes in plasma renin and blood pressure.

Conventionally used criteria for predicting the blood pressure response to surgery in renovascular hypertensive disease rely on the demonstration of renin dependency. To assess the validity of this, we have related post-operative changes in plasma renin to the efficacy of surgical treatment of renovascular hypertension. We report nine hypertensive patients with unilateral renal disease and raised peripheral plasma renin activity (PRA), who were studied before and after either nephrectomy or renal artery stenosis bypass. In four patients blood pressure fell to normal levels, and has remained normal without treatment for periods varing from one to four years. In only one of these patients did renal vein renin studies indicate hypersecretion of renin on the operated side with contralateral suppression. Of the remaining five patients, three showed partial reduction of diastolic blood pressure and in two blood pressure was unchanged, although it was more easily controlled with antihypertensive medication. In all patients studied, peripheral venous plasma renin activity fell significantly after surgery, becoming normal in seven patients: in one of these blood pressure was unchanged, and it remained significantly elevated in two. Thus, correction of renin hypersecretion is not necessarily associated with restoration of blood pressure to normal. Tests for surgical correctability of renal hypertension which attribute a central role to renin hypersecretion may therefore yield misleading results.

Adult↗
PubMed1980

Plasma renin in hypertensive patients: significance in relation to clinical and other biochemical features.

Presenting features of 221 hypertensive patients were examined in relation to plasma renin. One hundred and seventy-six patients had essential hypertension, of these 47 had high plasma renin activity (PRA), 80 had normal PRA and 49 low PRA. When the groups with high and low PRA were compared with age and sex matched patients with normal PRA there was no difference with respect to clinical, radiological, electrocardiographic and biochemical characteristics. Twenty-five patients had radiological evidence of unilateral renal or renovascular disease and twenty patients had accelerated hypertension with advanced fundal changes: both these groups had more severe hypertension, a higher plasma renin and evidence of greater cardiovascular morbidity than patients with essential hypertension. Morbidity was equally high in patients with accelerated hypertension whether PRA was high or normal. There is therefore no evidence to support the view that renin is an important factor in assessing risk in hypertension. If, on the other hand, specially referred patients with renovascular and accelerated hypertension are pooled with other hypertensive patients, a spurious association between renin and cardiovascular morbidity will be created.

Adult↗
PubMed1979

Salt intake and diuretic treatment of hypertension.

24 h urinary sodium excretion was used to monitor salt intake in 36 patients with essential hypertension to determine whether limitation of the antihypertensive action of thiazide diuretics could be explained by increased salt appetitie stimulated by salt depletion. Sodium excretion in these patients was similar before treatment to that observed in normotensive controls, and no change was observed during 2 years' treatment with bendrofluazide. However, plasma-renin rose progressively over the 2 years even in 5 of 8 patients whose renin was not stimulated initially by diuretics. Thus, there is no evidence that a voluntary increase in salt intake limits the efficacy of diuretic treatment; on the other hand, progressive stimulation of the renin-angiotensin system may be an important limiting factor to the antihypertensive action of diuretics. If so, the antihypertensive effect of dietary salt restriction may be similarly limited.

Adult↗
PubMed1979

Pressor responsiveness to angiotensin in renovascular and steroid hypertension.

1. The pressor response to angiotensin II was reduced in rats with early (less than 6 weeks) and chronic (greater than 4 months) Goldblatt two-kidney, one-clip hypertension and enhanced in DOCA-salt hypertension. 2. Converting enzyme inhibition with captopril brought the angiotensin pressor response curves into closer proximity although the DOCA hypertensive rats were minimally hyper-responsive and rats with early and chronic renovascular hypertension showed slightly reduced responsiveness. 3. After bilateral nephrectomy the pressor responses to angiotensin were similar. 4. The pressor response to angiotensin II in these animals was inversely related to plasma renin concentration and therefore largely dependent upon receptor occupancy by endogenous angiotensin II. There is no evidence for enhanced pressor responsiveness to angiotensin in either renovascular or DOCA hypertension.

Angiotensin II↗