ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Brattleboro rats without diabetes insipidus were subjected to sodium chloride enrichment (20-fold increase in dietary salt) at various stages of their development. Salt supplementation in the adult rat produced higher systolic blood pressure (SBP), particularly in males (142 ± 3 versus 110 ± 3 mmHg in control. The blood pressures of females on salt-supplemented diets during pregnancy decreased from 136 ± 1 to 121 ± 2 mmHg, although throughout this period the blood pressures for these rats were greater than for the control pregnant rats. Pregnant females on salt-supplemented diets also showed higher sodium concentrations in the amniotic fluid compared with controls (155 ± 3.4 versus 134.1 ± 6.0 mmol/l). Salt supplemented lactating mothers produced milk with similar sodium concentrations to those of the controls, but the urinary sodium concentrations of pups suckling on the former were greater than in the controls. It is concluded that the suckling pups were also salt-enriched. Rats were submitted to salt-enriched regimes in utero, during suckling, post-weaning and post-pubertally, or permutations thereof. Salt supplementation post-weaning led to consistent elevation in arterial blood pressure with males being more susceptible than females. The degree of elevation was increased if the salt-supplement was present during suckling (132 ± 1 versus 112 ± 1 mmHg) and was greatest when the salt-supplemented regime was administered both in utero and during the post-weaning period (154 ± 2 versus 112 ± 1 mmHg). Rats exposed to salt enrichment in utero, or in utero and during suckling, but fed a control diet post-weaning and into adulthood did not develop hypertension as adults. Indeed, in some these rats showed a lower blood pressure than control animals which had the regular diet throughout their life from conception to adulthood. Of the hormones which were measured, the most relevant was perhaps 18-OH-DOC which showed a specific sex difference in animals on the control diets (males: 17.9 + 3.6 ng/ml; females: 86.4 ± 14.0 mg/ml). Furthermore, 18-OH-DOC concentrations were increased in females on salt-enriched diets but not in males on the same diet (females: 156.4 + 16.5 ng/ml; males: 18.6 ±2.1 ng/ml).

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

In 62 untreated patients with essential hypertension, arterial baroreflex sensitivity (BRS) for heart rate, i.e. the change in pulse interval in response to a phenylephrine-induced increase in blood pressure, was compared with (1) haemodynamic changes during mental arithmetic, a reaction time test, isometric and bicycle exercise; (2) plasma noradrenaline (PNA) concentrations at rest, and during bicycle exercise and; (3) the variability of ambulatory intra-arterial blood pressure. Subjects with diminished BRS showed the following responses: (1) higher mean arterial blood pressure (MAP) during all four stimuli; (2) a greater pressor response to cycling; (3) tended to have higher PNA concentrations during bicycle exercise and; (4) greater variation in ambulatory blood pressure. Furthermore, an increased pressor response to the reaction time test and increased ambulatory blood pressure variability was seen in younger subjects with reduced BRS. When subjects were subgrouped according to their WHO stage of hypertension, there were significant inverse relationships between BRS and the pressor responses to mental arithmetic, the reaction time test and cycling, and with ambulatory blood pressure variability only in those subjects without ECG or radiographic evidence of left ventricular enlargement (WHO stage I hypertension; n=42). None of these correlations were present in subjects with one or both of these clinical findings (WHO stage II; n=20). Pressor responses to the four laboratory stimuli and ambulatory blood pressure variability were similar in both groups, despite significantly higher arterial pressure and significantly lower BRS in WHO stage II subjects. These results suggest that differing mechanisms may be responsible for the regulation of blood pressure variation in these two groups. The arterial baroreflex can buffer acute changes in blood pressure in subjects with WHO stage I hypertension, but this ability is attenuated with progressive reduction of BRS. With the development of clinically evident cardiac adaptation to hypertension (WHO stage II), the contribution of the arterial baroreflex to the regulation of blood pressure is no longer detectable and the influence of cardiac and somatic afferents to reflex circulatory adjustments to activity may predominate

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

In order to examine the role of central catecholaminergic neurons in hypertension, the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of catecholamines, was studied in the hypothalamus, midbrain, pons-upper medulla, mid-medulla and lower medulla of one-kidney, one clip (1-K.1C) and two-kidney, one clip (2-K.1C) hypertensive rabbits and their respective operated controls (1-K,1Cc and 2-K,1Cc). Comparing the 1-K.1C group to the 1-K,1Cc group, the activity of TH was increased by 79% in the hypothalamus (P<0.02), 37% in the mid-medulla region (P<0.02) and was unchanged in the midbrain, pons-upper medulla and the lower medulla. Comparing the 2-K.1C group to the 2-K,1Cc group, the activity of TH was increased by 89% in the mid-medulla (P<0.01), decreased by 36% in the ponsupper medulla (P<0.01) and unchanged in the hypothalamus, midbrain and lower medulla. These results indicate that similarities and differences exist in the contribution of central catecholaminergic neurons to the pathophysiology of 1-K.1C and 2-K.1C hypertension in rabbits.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Beta-adrenoceptor-mediated relaxation of isolated arteries from spontaneously hypertensive rats (SHR) was studied. The relaxation responses of the femoral arteries of pre-hypertensive SHR (PHSHR) to isoprenaline (ISO) and dibutyryl cyclic AMP were less than those of the age-matched tissues of rats of the Wistar-Kyoto strain (WKY). The responses of the mesenteric arteries of PHSHR to ISO and noradrenaline (NA) but not fenoterol (FEN) and forskolin were diminished when compared to those from the WKY tissues. The diminished relaxation response to ISO was observed in the SHR arteries with and without endothelial cells as compared to similar arteries from WKY. Relative potency ratios of ISO:FEN:NA and the Schild plot data for atenolol and butoxamine suggested that there were only β2adrenoceptors and predominantly β2-adrenoceptors mediating relaxation in the femoral and mesenteric arteries, respectively. There was no difference in β-adrenoceptor subtypes between the SHR and WKY arteries. The evidence in this study suggests that pradrenoceptor-mediated relaxation was diminished in the femoral and mesenteric arteries of PHSHR.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A unique tissue kallikrein-binding protein was identified and partially characterized in the brain and serum of Sprague-Dawley rats and in the serum-free conditioned media of mouse anterior pituitary cells (AtT 20) and rodent neuroblastoma ? glioma hybrids (NG108-15). Kallikrein and kallikrein-binding protein(s) form SDS--and heat-stable complexes with a molecular weight (Mr) of ~92 000. The complex formation of125I - labelled kallikrein and the binding protein in the serum and brain is inhibited by excess unlabelled rat urinary kallikrein, rat arginine esterase A (a kallikrein-like kininogenase), and human urinary kallikrein. When the active site of kallikrein was blocked by phenylmethylsulfonyl fluoride or D-Phe-D-Phe-L-Arg-CH2CI, no complex formation was detected. Kallikrein-binding protein only forms complexes with active kallikrein or trypsin-activated prokallikrein but not with prokallikrein.125l-labelled kallikrein forms a 92-kilodalton protein with binding protein in various brain regions of perfused normotensive rats of the Wistar-Kyoto strain (WKY), including the cerebral cortex, cerebellum and brain stem; but complex formation was not found in corresponding brain regions of the spontaneously hypertensive rat (SHR). Similarly, the kallikrein-binding protein was identified in various tissues including thymus, lung, liver, prostate, Cowper's gland, adrenal gland, kidney, and pancreas of WKY rats but not in tissues of SHR. The results suggest a major difference in the kallikrein-binding protein in hypertensive versus normotensive rats. The role of this specific kallikrein-binding protein in cellular hemodynamic processes and blood pressure regulation remains to be investigated.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

In order to verify, whether baroreflex sensitivity is changed centrally in DOCA-salt hypertension, the left aortic depressor nerve (ADN) was electrically stimulated in DOCA-salt hypertensive rats. After 3 weeks, tail-cuff systolic pressure was significantly higher in DOCA-salt treated rats than in untreated rats (169 ± 4 versus 130 ± 4 mmHg, respectively; P< 0.001). After cutting both ADN and the carotid sinus nerves, the central cut end of the left ADN was electrically stimulated and frequency dependent depressor, bradycardic and sympatho-inhibitory responses were elicited in both control and DOCA-salt hypertensive rats. However, these responses were significantly smaller in DOCA-salt hypertensive rats than in normotensive controls. Bradycardic and sympatho-inhibitory responses to i.v. injection of norepinephrine were also blunted in DOCA-salt hypertensive rats. These findings suggest that baroreflexes were centrally attenuated in DOCA-salt hypertensive rats and possibly contribute to overall baroreflex attenuation.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The plasma concentration of atrial natriuretic peptide (ANP) and the density and affinity of binding sites for ANP in platelets was investigated in patients with essential hypertension. Severe hypertensives were studied whilst still on medication. All subjects were ambulatory and were investigated after 3 days on a 135 mmol/day sodium intake. Plasma ANP levels were significantly increased from 13 ± 1 fmol/ml in healthy normotensive controls to 39 ± 5 fmol/ml (P<0.01) in moderate or severe hypertensives uncontrolled by treatment. Platelet binding sites varied in a non-linear inverse relationship to plasma concentration of ANP (r=-0.76), from 14 ± 1 fmol per 109platelets in healthy subjects to 8 ± 1 fmol per 109platelets in severe hypertensives, uncontrolled by treatment, (P<0.05). The latter group with elevated plasma ANP and reduced density of ANP platelet sites, had a high incidence of left ventricular hypertrophy and increased left ventricular mass index by echocardiography. When a diuretic was added or stopped, plasma ANP and ANP sites in platelets varied inversely, with lower ANP concentration in plasma and higher density of ANP receptors in platelets when receiving the diuretic. Plasma concentrations of ANP are increased and the density of ANP receptors is decreased in moderate to severe uncontrolled essential hypertensives with left ventricular hypertrophy, but neither parameter differs from those of healthy age-matched volunteers in mild essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

In order to investigate the role of cardiac hypertrophy in atrial natriuretic peptide (ANP) secretion in patients with essential hypertension, plasma levels of ANP were measured after overnight rest in 36 patients with untreated hypertension and in 31 normotensive controls. In the hypertensive subjects, plasma levels were correlated with left ventricular (LV) and left atrial abnormalities detected by chest X-ray, electrocardiogram (ECG) and M-mode? echocardiography. Plasma ANP levels in patients with hypertension averaged 146 ± 27 pg/ml compared to 46 ± 7 pg/ml in the normotensive subjects (P<0.001). In patients with hypertension a significant correlation was found between ANP and supine systolic blood pressure (r=0.54, P<0.001) and between ANP and diastolic blood pressure (r=0.38, P<0.05). Furthermore, plasma ANP levels were correlated with total heart volume (r=0.68, P<0.01), LV mass (r=0.525, P<0.001), LV posterior wall thickness (r=0.39, P<0.05), Sokolow-Lyon index (r=0.721, P<0.001) and end-diastolic diameter of the left atrium (r=0.334, P<0.05). The results suggest a contribution of LV and left atrial abnormalities to ANP secretion in essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID