摘要:

SUMMARY Inactive renin and active renin from human kidney and human plasma were prepared in highly purified forms by three steps of chromatography on Octyl-Sepharose, Immunoafflnity chromatography, and pepstatin-amino hexyl Sepharose CL-4B. The inactive renin and active renin from human kidney had molecular weights of 51,000 and 44,000 as measured by a calibrated gel filtration column run with internal molecular weight standards. Molecular weights of plasma Inactive renin and active renin were 56,000 and 51,000 respectively. Both inactive and active renins were found to be heterogeneous, consisting of several components with different isoelectric points. Renal inactive renin has higher pi values of 6.40,6.10, 5.90,5.61, and 5.40. Renal active renin has pi values of 5.73,5.40,5.25, and 5.13. The pi values of plasma inactive renin were 6.37, 6.08, 5.77, 536, and 5.25; of plasma active renin, 5.68, 5.40, 5J3, and 5.25. Trypsin activation and plasmin activation of plasma inactive renin produced an active enzyme with similar molecular weight but lower pi values. Acid activation of inactive renin did not change the molecular weight and pi values.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Changes in the actirity of hypothalamic and brain-stem adrenergic neurons have been reported in young spontaneously hypertensive rats (SHR) prior to the development of hypertension. We have measured central α- and β-adrenoceptor concentrations in 4-week-old SHR and Wistar-Kyoto (WKY) controls by direct radioligand binding studies using [3H]prazosin (α1), [3H Clonidine (α2) and [123]iodohydroxybenzipindolol (β). The concentration of α2-adrenoceptors was significantly elevated in the bypothalamus of the SHR, 156.9 ± 10.4 compared with WKY, 119.4 ± 10.0 fmole/rag protein (n = 7, mean ± SEM,p< 0.0125). Alpha2-adrenoceptor concentrations in both the brain stem and cerebral cortex were similar in the two groups of animals. The increase in hypotbalamic adrenoceptors was specific for ai-adrenoceptors, since similar concentrations of α2and β-adrenoceptors were found in this region.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY The risk parameters for the development of essential hypertension (EH) were evaluated In a group of adolescents with borderline hypertension. A population comprised of 50 adolescents with systolic or diastolic blood pressure between the 90th and 95th percentile was compared to a normotenslve (< 90%) family history-negative control population. Evaluative parameters included genetic risk, resting blood pressure, resting heart rate, and cardiovascular response to mental stress. In a follow-up period of up to 41 months, 28 borderline hypertensive adolescents (56%) developed fixed EH. At the time of initial evaluation, these 28 hypertensive adolescents had a strong family history of EH, higher resting heart rate (p< 0.01) and blood pressure (p< 0.01), and a greater cardiovascular response to mental stress (p< 0.001) compared to the normotenslve family history-negative control population. Time series analysis of the stress phase also demonstrated a rhythmic cardiovascular response In the normotensive group [p< 0.05) that was not present in the hypertensive group. These results indicate that adolescents with borderline hypertension displaying these characteristics have a greater risk for EH than previously reported.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Effects of intracerebroventricular (i.c.r.) injection of [D-Ala'1-methionine-enkephalinamide (DAME) on blood pressure (BP), heart rate, and baroreceptor reflex sensitirity were studied in conscious cats. DAME was administered at doses between 5 and 100 nmoles. Blood pressure and heart rate increased dose dependency. The sensitivity of the baroreceptor reflex was attenuated for IS to 60 minutes after DAME administration; this was independent of the BP changes. The effects of enkepbalin on BP and baroreceptor reflex were abolished by i.c.v. naloxone. DAME caused pathological changes in the electroencephalogram (EEG) characterized by sharp waves in the hippocampus recordings and a loss of theta activity in the electrocorticogram. Behavioral changes were characterized by decreased physical mobility and anxiousness. These behavioral and EEG changes lasted for a longer period of time than the cardiovascular changes; they were also counteracted by naloxone.It is concluded that DAME produces a centrally mediated vasopressor response and a baroreceptor reflex attenuation and that, with respect to the time course, the effects on the baroreceptor reflex are separated from those on BP behavior and EEG, but not on heart rate. The fact that all effects of enkephalin on the parameters tested in the present experiment were completely antagonized by naloxone suggests that they are mediated by naloxone-sensitive enkephalin brain receptors.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Transplantation of arteries into the anterior eye chamber rats for 8 weeks was used to test the hypothesis that the oeurohumoral enrironment is important in establishing the altered membrane potential (observable during electrogenic ion transport inhibition) of vascular muscle in hypertension. When caudal arteries from 12- to 16-week-old spontaneously hypertensive rats (SHR) or genetically matched Kyoto-Wistar normotensive rats (KNR) were transplanted into the opposite strain, there was no change in the transportinhibited membrane potential (Em) of the arterial muscle cells from that found in freshly excised donor arteries. However, when caudal arteries from 2-week-old animals were transplanted into the anterior eye chamber, the arteries always developed appropriate Emfor the host animal. In other words, a genetically KNR artery developed the Emof an SHR artery in an SHR host; conversely, a genetically SHR developed the Emof a KNR artery in the KNR host. These results provide evidence that: 1) differences between the Emof caudal arteries from SHR and KNR are not inherent in those muscle cells; 2) the change in Emis triggered in young animals preceding development of hypertension, but not after hypertension is established; and 3) the Emalteration of the caudal artery is independent structural changes that occur in artery as a result of increased blood pressure (because KNR transplants were not connected in series with the host anterior eye chamber vasculature and subject to the elevated blood pressures). We conclude that the arterial muscle cells up to a certain age respond an external factor that regulates their E$ and presumably their sensitivity to vasopressor agents.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Treatment of 2-montb-old spontaneously hypertensive rats (SHR) and age-matched Wlstar- Kyoto (WKY) normotensive controls with the dopamine agonist, bromocriptine, for 7 days significantly affected hormonal responses to immobilization stress in both groups. However, basal blood pressures and pressor responses to immobilization stress were significantly reduced only in SHR. Basal levels of catecholamines were similar in the two groups of rats, but catecbolamlne responses to immobilization stress following saline (vehicle) treatment were markedly greater in SHR; following bromocriptine treatment for 7 days, catecholamine responses were similar in the two groups. Basal serum prolactin levels and prolactin responses to immobilization were greater in SHR after saline treatment; after bromocriptine, they were similar in the two groups. Basal plasma renin activity (PRA) and PRA responses to immobilization were significantly less in SHR following saline treatment; after bromocriptine treatment, these responses were paradoxically greater in SHR without being significantly changed in WKY. Basal levels of plasma aldosterone and corticosterone following saline were significantly greater, but responses to immobilization less, in SHR. Bromocriptine treatment decreased aldosterone and corticosterone responses to stress in WKY but paradoxically increased these responses in SHR. These results suggest that increased pressor responses to stress are dependent on heightened sympathetic nerve activity, perhaps secondary to decreased central dopaminergic activity. Increased basal prolactin levels and stress-mediated prolactin responses may be related to decreased central dopaminergic activity. Paradoxical PRA, plasma aldosterone, and corticosterone responses to stress following bromocriptine suggest altered dopaminergic modulation of these hormones in the SHR.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Comparative studies of plasma norepinephrine in patients with essential hypertension and in nonnotensive controls have consistently reported higher mean resting levels of norepinephrine in the hypertensive groups, but the hypertenslve-nonnotenslve differences have often been small and, in about three-fifths of the studies, not statistically significant. The author reviewed the medical literature to test the hypothesis that, during stress, hypertenslve-nonnotenslve differences in norepinephrine become more apparent. Among 24 studies involving orthostatic stress, the increment in norepinephrine with standing was similar for hypertensives and normotensives (239 vs 230 pg/ml). In contrast, among eight studies involving exercise, the increment in norepinephrine was significantly greater in hypertensives (834 vs 450 pg/ml). For both standing and isotonic exercise, absolute changes in norepinephrine with stress correlated with basal norepinephrine across the hypertensive but not the nonnotensive groups. These results are consistent with the existence within the hypertensive population of a subgroup of patients with elevated norepinephrine levels at rest and excessive sympathetic responsiveness to stress. However, the available literature is deddedly lacking in studies about other types of stress besides standing and exercise.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY The relationship between alcohol consumption and systolic and diastolic blood pressure (BP) was examined in 2482 men and 2301 women 20 years of age or older in nine North American populations. Men at the highest level of alcohol consumption ($ 30 ml alcohol per day) had the highest BP, while women either at the highest lerel of alcohol consumption or consuming no alcohol had the highest BP. Men aged 5: 35 years of age consuming S 30 ml alcohol per day were 1.5 to 2 times more likely to be hypertensive than nondrinkers. Multivariate analysis showed systolic and diastolic BP in both men and women to be positively and significantly (p< 0.05) related to alcohol consumption, and this relationship was independent of the potential confounding effects of age, obesity, cigarette smoking, regular exercise, education, and gonadal hormone use in women. The regression coefficients indicated that an average of 30 ml of alcohol per day would produce a 2to 6 mm Hg increase in systolic BP. Analyses suggested the univariate U-shaped alcohol-BP association in women was confounded by differences in obesity and cigarette smoking in nondrinking women, and by very low alcohol consumption in hypertensive women using medication. Additional analyses indicated that alcohol consumed in the 24 hours prior to the study was much more strongly associated with elevated BP than alcohol consumed in the week prior to the study excluding the previous 24 hours. We conclude that alcohol appears to have a modest but consistent and independent effect on systolic and diastolic BP.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Tbe effects of potassium loading on blood pressure (BP) and the renln-angiotensin-aldosterone system were investigated in two-kidney, one clip Goldblatt hypertensive rats. Two series of experiments were performed: one was begun just after renal artery constriction, and tbe other, after hypertension had developed. Potassium loading significantly attenuated tbe development of hypertension, and was also able to abate existing renovascular hypertension. In both studies, potassium loading increased fluid intake and urine volume, which were accompanied by increased excretion of sodium and potassium. In spite of the massive diuretic effect, potassium loading significantly attenuated tbe increased plasma renin activity (PRA) induced by renal artery constriction, while it further enhanced the increased plasma aldosterone concentration (PAC) in twokidney, one clip Goldblatt hypertensive rats. There was no significant difference in the values of serum sodium and potassium between tbe two groups with or without potassium loading. These results suggest that potassium may attenuate the development of hypertension and reduce the elevated BP by diuresis and natriuresis and by suppression of the PRA in two-kidney, one clip Goldblatt hypertensive rats.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY A polypeptide fraction isolated from the urine of nonnotenslve subjects lowers blood pressure (BP) in a rabbit bioassay (mean BP decrease 33.8% ± 0.6%, SEM). Patients with primary hypertension exhibit reduced or no activity (mean BP decrease 8.8% ± 1.2%). In contrast, patients with secondary forms of hypertension show activity like nonnotensives (mean BP decrease 33.4% ± 1.0%). Tbe results the bioassay in tbe two patient groups correlate well with the family inddence of hypertension (68% and 37% for primary and secondary hypertension respectively). Cases with borderline hypertension fall into two groups; a larger one with vasoactivity in the bioassay and lower family inddence of hypertension; and a smaller group reacting like patients with primary hypertension. Only the latter group may represent an initial stage of primary hypertension. In nonnotenslve children and young men, an inactive fraction was found in 31% and 28% respectively. These inactive groups had twice the family inddence of hypertension compared to the groups with vasoactivity. These results suggest the existence of a possible genetic marker of primary hypertension and may offer the possibility to detect disease before its manifestation.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID