ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We have studied the norepinephrine (NE) uptake processes directly in synaptosomes isolated from the hypothalamus of both Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats. Both DS and DR rats were divided into two dietary groups, one high salt diet group and one low salt diet group. NE uptake was highly sodium dependent (averaging 80%) and ouabain sensitive (averaging 55%). The initial 3H-NE uptake by the hypothalamic synaptosomal fraction of DR and DS rats on a low salt diet during the first 10-min incubation period averaged 1.19 ± 0.083 and 1.50 ± 0.138 pmol/mg protein respectively while those of DR and DS on a high salt diet were 1.69 ± 0.124 and 1.64 ± 0.092 pmol/mg protein respectively. Baseline values of NE uptake on low salt diet were relatively high in DS compared to that in DR controls. High salt diet had a stimulatory effect on the net uptake of 3H-NE by hypothalamic synaptosomes of both strains of rats, DS showed an overall enhancement of 9% as compared to DR (42% increase, P=0.003). This differential enhancement by the high salt diet was apparently contributed to by the sodium-mediated and ouabain sensitive amine uptake process and possibly resulted from a defective inducibility of (Na+-K+)-ATPase in DS rats

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A total of 448 individuals ranging in age from 11 to 72 years were studied in a series of seven population-based surveys. Although the relationship was positive in all surveys, a significant correlation was noted between sodium-lithium countertransport and blood pressure in only three of the seven. Hypertensives as a group had significantly higher levels of countertransport than did those with a normal blood pressure. In stepwise regression analysis, however, entering weight into the equation eliminated a significant predictive effect of countertransport. Red cell sodium concentration and membrane leak did not bear any significant relationship to blood pressure. The association between countertransport and blood pressure appears to be weaker in the general population than previously reported for case-control studies

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A model of hypertension induced by mineralocoriticoid-excess in the sheep is described. Deoxycorticosterone acetate (DOCA), 100 mg/kg was implanted subcutaneously in adult sheep (n=13). Before DOCA administration, and for 30 days thereafter, mean arterial blood pressure (MAP), plasma electrolyte levels, plasma renin activities, water and electrolyte intakes and urinary outputs were monitored. Within 72 h after DOCA implantation MAP had risen from a control value of 83.0 ± 2.0 to 93.0 ± 3.0 mmHg, MAP stabilized at 114.0 ± 3.0 mmHg three weeks later. Water intake had increased significantly by the 4th post-implant day and reached a maximum of 10.0 ± 1.2 I/day by the third week. The following biochemical changes were significant within 24 h after DOCA implantation; (1) plasma potassium fell from 4.4 ± 0.1 to 3.42 ± 0.13 mEq/l; (2) plasma sodium rose from 144.4 ± 0.6 to 147.0 ± 0.4 mEq/l; (3) plasma renin activity fell from 1.29 ± 0.42 to 0.13 ± 0.08 ng ANG l/ml/h. The rapidity of onset and reversal of arterial pressure elevation in this model render it a useful tool in providing insight into the mechanism responsible for this form of hypertension

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

During established two-kidney one clip hypertension in dogs blood pressure is elevated despite only slightly raised plasma renin activity. Dose dependent effects of exogenous angiotensin II on systemic and renal haemodynamics were examined before and after induction of this type of hypertension in conscious dogs. There was no difference in the response of blood pressure to angiotensin II in each group, suggesting that altered pressor sensitivity to angiotensin II is not the cause of the persisting hypertension. However sodium excretion, effective renal plasma flow and glomerular filtration rate were all decreased by angiotensin II in the normotensive group, but were unchanged or increased in the hypertensive group. Renal prostaglandin E excretion was also increased in the hypertensive animals, and further increased during infusion with angiotensin II. The altered renal response to angiotensin II in the hypertensive group may reflect changes in occupancy of angiotensin II receptors and/or enhanced renal release of vasodilator prostaglandins

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The objective of this study was to determine the sympathetic and renin-angiotensin contributions to the control of blood pressure and renal blood flow (RBF) in conscious normotensive and Goldblatt hypertensive dogs. Urapidil (2 mg/kg), an alpha-adrenoceptor antagonist, and then captopril (0.2 mg/kg) were administered acutely intravenously (i.v.) to instrumented normotensive and two-kidney, one clip Goldblatt hypertensive dogs. Urapidil decreased mean arterial blood pressure (MAP) in the hypertensive (n=11) and normotensive dogs (n=9). Contralateral RBF was unchanged in the hypertensive, but was increased in the normotensive dogs. Captopril caused a further fall in MAP of the hypertensives and increased RBF. MAP of the normotensives was further decreased and RBF increased by captopril. Urapidil increased plasma renin activity in the normotensives, but not in the hypertensives, whereas heart rate was increased and renal vascular resistance was decreased in both groups. In nine hypertensive dogs, captopril alone (0.2 mg/kg i.v.) had a smaller effect on MAP and RBF than after alpha blockade. These results indicate that the combined influence of the sympathetic and renin-angiotensin systems accounts for a major portion of the MAP increase in two-kidney, one clip Goldblatt hypertension, and elimination of their influence causes profound hypotension and renal vasodilatation

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The hindlimb and renal vasodilator responses produced by electrical stimulation of the glossopharyngeal nerve were examined in adult (six to eight months) male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) normotensive rats to ascertain whether central neurogenically activated vasodilator capacity of these regional vascular beds is altered in SHR. Changes in systemic blood pressure and regional blood flow were simultaneously measured, and vascular resistance was calculated. Glossopharyngeal nerve stimulation (3.0 volts, 0.3 ms) at the frequency of 10 Hz resulted in a significantly greater vasodilation (% decrease in resistance) in SHR than in WKY control for both the hindlimb (SHR -13.0 ± 1.5% versus WKY -3.4 ± 1.6%, P<0.01) and renal (SHR -7.6 ±0.6% versus WKY -1.3 ± 0.4%, P<0.01) vascular beds. The linear portion of the frequency^response curves of hindlimb or renal vasodilation of SHR was shifted parallel to the left of the WKY curve. Stimulus frequencies required to produce a 20% reduction in hindlimb resistance and a 10% reduction in renal resistance were lower in SHR (hindlimb 17.0 ± 1.8 Hz; renal 19.9 ± 1.4 Hz) than in WKY control (hindlimb 24.6 ± 1.1 Hz; renal 39.3 ± 4.8 Hz; P<0.01). The maximal vasodilator response to glossopharyngeal nerve stimulation in the hindlimb vascular bed was similar in SHR and WKY control, but in the renal vascular bed SHR showed a greater maximal response compared to WKY normotensives (SHR -16.3 ± 0.9% versus WKY-12.7 ± 1.6%, P<0.01). During glossopharyngeal nerve stimulation, greater decreases in mean arterial pressure were noted in SHR, whereas the blood flow responses were similar between the two groups. These results show a greater sensitivity of SHR to glossopharyngeal nerve stimulation to produce neurogenic vasodilation in the hindlimb and renal vascular beds with either preserved or augmented maximal capacity. The data do not support the concept that decreased neurogenically induced vasodilation central to the baroreceptors is involved in the maintenance of elevated vascular resistance and arterial pressure in SHR

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Systolic blood pressure was measured on a total of 1855 occasions in 1307 children aged four and five years, and compared with values obtained since birth in the same children. There was a rapid rise in blood pressure in the first month of life. The mean blood pressure then only rose from 93 mmHg at six months to 98 mmHg at five years. The 95th percentile was 113 to 114 mmHg over this period. In children aged four and five years, over the ranges studied, blood pressure was not importantly affected by place of measurement, time of day, time since previous meal, or ambient temperature. However, blood pressure was approximately 1.6 mmHg higher in winter than in summer (P<0.01). Nevertheless, it is unlikely that these factors are of significance when making clinical measurementsBlood pressure was correlated with weight at all ages. Between the ages of four and five years, the index, weight/height1.70was the best function of adiposity tested that was independent of age between four and five years. It is suggested that this or the Quetelet Index (weight/height2) are suitable indices for adjusting blood pressure for body build in children aged four and five years

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Measures of maximal rates of lithium-sodium countertransport and frusemide-sensitive sodium and potassium cotransport have been proposed as biochemical markers for human essential hypertension. The stability of these functions over time within the same individuals has led to the suggestion that maximal transport capacities are genetically determined. The present study confirms the reproducibility of functional assays of countertransport and cotransport in human erythrocytes after overnight storage and over a six-month period in normal volunteers and provides estimates of the magnitude of technical error for each assayA long-term dietary intervention study in a group of obese adolescents demonstrated marked increases in erythrocyte sodium levels and maximal frusemide-sensitive sodium and potassium fluxes but no changes in cell potassium or water and no effect on lithium-sodium countertransport. A correlation between the decrease in percentage of body fat and the increase in cell sodium content suggests a link between the metabolic effects of dieting and control of erythrocyte cation handlingAlthough the mechanism linking dietary calorie restriction and changes in erythrocyte cation metabolism is unknown, evaluation of body weight, and especially recent weight loss, is important in studies of erythrocyte transport. Conclusions regarding genetic contributions to the activities of lithium-sodium countertransport and sodium-potassium cotransport systems will be strengthened by clarification of environmental regulators

ISSN:0263-6352    

出版商:OVID    

年代:1984

数据来源: OVID