摘要:

SUMMARY Two groups of 10 rabbits were subjected to renal cellophane wrapping and sham operation. Their initial mean arterial pressures (MAP) were similar, 92 ± 1.5 and 90 ± 2.9 mm Hg. Six weeks later three experimental periods began, each of 2 weeks' duration, on low, normal, and high salt (1,9, and 50 mmole Na/100 g food) diets. Each group had two subgroups: rabbits with both kidneys, and rabbits with only one kidney and previous nephrectomy. The hemodynamic findings were similar in each group. After sham operation, the range of dietary salt produced no significant circulatory changes. After wrapping, MAP was reduced on low compared with normal and high salt diets (122 TS 132 and 136 mm Hg;p= 0.01). This was entirely due to lowering of cardiac output (CO) on low salt; on normal and high salt CO was higher than in sham-operated rabbits. Total peripheral resistance (TPR) in the wrapped animals was unaffected by diet, i.e., 21.4,20.5, and21.2 units on low, normal, and high salt— about 35% above values of sham-operated rabbits. Volume-related CO changes therefore produce long-term changes in MAP without alteration in TPR, which is not in conformity with the autoregulation theory of hypertension. Evidence of impaired capacity of wrapped compared with sham-operated rabbits to handle salt included diet-related bematocrit changes, lower creatinine clearance, and some differences in renin responses to salt. Giving saralasin reduced TPR while the rabbits were on low salt; the fall was twice as great in wrapped compared with sham-operated rabbits.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Heart rate (HR), systolic (SBP), and diastolic (DBP) blood pressure levels were compared ID 60 young males during various resting and stressful conditions. Subjects included 29 who had and 31 who had not shown occasional casual SBP readings $ 135 mm Hg under low stress conditions. These groups were further divided into those who snowed above-average and below-average HR increases at onset of a stressful shock-avoidance task (high vs low HR reactors). High HR reactors, who were equally distributed in both casual SBP groups, also showed higher SBP than low reactors during avoidance, and higher HR and SBP during a pre-stress rest period and two other stresses, the cold pressor test and viewing an erotic dim (p's< 0.01). During less stressful conditions (relaxation in the laboratory, family doctor readings, and self-determinations at home), no HR, SBP, or DBP differences were seen between high and low HR reactors. Subjects with casual SBPs $ 135 showed higher mean SBP than those with casual SBPs< 135 under all resting and stressful conditions (p's< 0.05) and generally higher DBP as well. Highest mean SBP levels during prestress rest and later stresses were shown by subjects with both casual SBPs i> 135 and high HR reactivity to the avoidance task, and lowest by subjects with neither trait. Incidence of parental hypertension was greater among high than low HR reactors, and greatest among high reactors with casual SBPs 2: 135, suggesting that HR reactivity to stress may help predict future hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Disruption of the blood-brain barrier (BBB) daring acutehypertension may contribute to hypertensive encephailopathy. In this study we tested the hypothesis that, in chronic hypertension, vascular changes might influence the susceptibility of the BBB to disruption. Spontaneously hypertensive rats (SHR) and normotensive rats (WKY), 3-4 months of age, were anesthetized and acute hypertension was produced by infusing phenylephrine intravenously (i.v.). Permeability of the BBB was studied with radioactive iodine serum albumin (RISA) injected i.v. The ratio of brain-to-blood RISA was used as an index of permeability of the BBB expressed as protein transfer. In both SHR and WKY at resting arterial pressure, the protein transfer was< 0.10%. In WKY exposed to acute hypertension (mean arterial pressure increased by 87 ± 7 mm Hg), the protein transfer was 2.77 ± 0.60%. In SHR with acute hypertension superimposed on chronic hypertension (arterial pressure increased by 80 ± 7 mm Hg), the protein transfer was 1.16 ± 0.45% (p< 0.05, SHR vs WKY). These data suggest that cerebral vessels are less susceptible to disruption of the BBB by acute hypertension in SHR than in WKY. We speculate that the finding of reduced susceptibility to BBB disruption in chronic hypertension may explain, in part, the apparent susceptibility of previously normotensive patients to acute hypertensive encephalopathy.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Urinary enzymes that hydrolyze the artificial substrate a-N-p-tosyl-L-argiiilne methyl ester (TAME) were studied in Dahl salt-sensitive (S) and salt-resistant (R) rats. Total urinary TAME esterase activity (kallikrein and noo-kallikrein) snowed a marked increase with dialysis against water, but only in hypertensive S rats with proteinuria. This phenomenon suggests the presence of dlalyzable TAME esterase inhibitors) in urine following renal damage, but these data do not define what urinary esterases might be affected. Partially purified urinary kallikrein exhibited a ratio of kininogenase to esterase activity which was equal for S and R rats. Thus, the marked discrepency between klnlnogenaie and esterase activities reported by Carretero et al. with S and R whole urine is not a function of the S and R kallikrein molecules but is probably related to interfering substances in the whole urine. Urinary kallikrein excretion was measured on individual rat samples by TAME esterase activity following dialysis and separation from non-kallikrein TAME esterase$) using DEAE-Sephadex mlnicolumns. S rats had lower urinary kallikrein excretion than R when the S rats were hypertensive and snowed marked proteinuria. Young S and R rats raised on low salt showed similar blood pressures and similar kallikrein excretion. High salt (8% NaCl) diet decreased kalllkrein excretion in both S and R, bat the decrease was greater in the S rats which became hypertensive and had increased urine protein excretion. These data suggest that the lower urinary kallikrein excretion in S rats relative to R rats is probably a consequence of hypertension and renal damage rather than a primary cause of hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID