ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Measurements of the plasma concentration of noradrenaline, or more specifically the rate at which noradrenaline enters plasma, provide a useful guide to sympathetic nervous system function in humans. The overall rate of release of noradrenaline to plasma gives an overview of sympathetic nervous system activity (integrated nerve firing rate), detecting generalized changes, whether occurring as a reflex response, produced by drugs, or accompanying disease processes. The pattern of sympathetic nervous activation, however, is not delineated, only the net change in neurotransmitter release. Measurement of regional rates of noradrenaline release allows the clinical assessment of organ-specific sympathetic nervous tone, and consequently more penetrating analysis of sympathetic nervous system pathophysiology in disease states. The major problem in interpreting regional noradrenaline spillover measurements lies in the difficulty in differentiating those changes in noradrenaline spillover due to altered nerve firing, from those due to extraneous factors which might also affect spillover, such as the possible influence of blood flow on noradrenaline washout.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The binding of125I-angiotensin II to human blood cells was investigated. Blood was drawn from healthy volunteers and platelets prepared with minimal contamination of red cells and white blood cells (<0.1 %). Using thin layer chromatography, degradation of125l-angiotensin II by platelets could be demonstrated in the presence of various enzyme inhibitors. However, when incubated, with 1 mM diisopropylfluorophosphate (DFP) or 1 mg/ml bacitracin, no breakdown of125I-angiotensin II could be detected. The amount of specifically bound125I-angiotensin II increased linearly with the number of cells per tube. Binding reached a plateau within 90-120 min at 37°C, and was stable thereafter. Specific binding was reversible. No binding could be detected at 4°C. Specific binding of125I-angiotensin II was saturable. Scatchard analysis of binding by platelets of healthy volunteers revealed one class of binding sites with an apparent Kdof 127 + 16 pM and a maximal binding capacity of 7.9 ± 1.5 binding sites per cell. Competitive displacement of125I-angiotensin II binding by angiotensin ll-analogues showed a rank order of effectiveness. Unrelated peptides, e.g. bradykinin, vasopressin and enkephalin, did not displace specifically bound angiotensin II. Human mononuclear leucocytes were prepared by a Ficoll-isopaque gradient. However, these cells could not be used for studies of specific binding, since enzymatic degradation of125l-angiotensin II could not be prevented despite addition of various enzyme inhibitors. Time-dependent uptake of125I-angiotensin II showed no stable plateau. Thus our study shows specific binding of125l-angiotensin II to human platelets. These cells might serve as an in vivo model of angiotensin II receptor regulation in clinical studies.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Blood pressure readings obtained by the physician in his office and ambulatory blood pressures recorded with the semi-automatic Remler device, were compared during a controlled antihypertensive drug trial. Either timolol or methyldopa was administered in in double-blind fashion to 30 patients with uncomplicated essential hypertension. All exhibited a diastolic office blood pressure>95 mmHg at the end of a four-week placebo period. All patients then received a combination of hydrochlorothiazide (25 mg/day) and amiloride (2.5 mg/day). After four weeks of diuretic therapy, timolol (10 mg/day, n=14) or methyldopa (250 mg/day, n=16) were added randomly for six weeks. The dose of all antihypertensive agents was doubled after two weeks of therapy with diuretics combined with timolol (n=7) or methyldopa (n=16) because of the persistence of diastolic blood pressure levels>90 mmHg at the office. When assessed in the office, the antihypertensive effect of timolol and methyldopa was similar. During ambulatory blood pressure monitoring, however, pressure levels were lower in the patients given timolol (P<0.05 for the diastolic). With both regimens, the blood pressure response measured outside the clinic during usual daily activities could not be predicted from that observed with office blood pressure readings. Furthermore the magnitude of the drug induced blood pressure decrease was more reproducible in time when determined outside the clinic. These data suggest that ambulatory blood pressure monitoring is more precise in evaluating the efficacy of antihypertensive therapy than office blood pressure measurement.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The presence of volume receptors and a potent natriuretic factor (ANF) in mammalian cardiac atria strongly suggests a central role of the atria in extracellular fluid volume regulation. ANF is stored within granules in atrial appendages, and their removal could alter the response to volume overload. We tested this hypothesis in conscious Wistar rats two weeks after sham operative or atrial appendectomy. The results indicate that removal of the atrial appendages significantly reduced their urinary excretion of water, sodium and potassium during the first hour following acute volume overload. It is concluded that atrial appendectomy alters the ability of rats to handle acute volume overload possibly through a reduction in the ANF available for release.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Oral administration of the angiotensin l-converting enzyme inhibitor captopril produced a substantial reduction of blood pressure in DOCA-salt hypertensive rats. After oral administration of captopril (30 mg/kg), mean blood pressure decreased from 172 ± 11 to 148 ± 9 mmHg (P<0.01) in one hour and its antihypertensive effects lasted for the next seven hours. Plasma vasopressin levels showed a marked elevation in DOCA-salt hypertensive rats compared with control values (22 ± 5 versus 5 ± 3 pg/ml). This increase in vasopressin was significantly reduced by captopril from 25 ± 5 to 8 + 6 pg/ml. In addition, whole body vascular reactivity to norepinephrine was examined. Responsiveness was at first attenuated but returned to control value in spite of reduction of both plasma vasopressin and blood pressure. Thus, captopril reduces blood pressure in DOCA-salt hypertensive rats and the fall in blood pressure is accompanied by reduction of plasma vasopressin and attenuation of vascular reactivity.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Angiotensin I was generated invitroin mouse plasma by addition of mouse submaxillary renin. After deproteinization on Dowex 50W-X2 ion exchange resin, the samples were separated by reverse phase liquid chromatography and the fractions analysed by radio-immunoassay for angiotensin I. Angiotensin I from mouse was injected into the jugular vein of a nephrectomized rat in order to generate angiotensin II and III of mouse origin. Carotid arterial blood was collected immediately, centrifuged and the plasma deproteinized and separated on high pressure liquid chromatography (HPLC). The fractions were analysed for angiotensin I, II and III by radioimmunoassays. Retention times for mouse angiotensins in the liquid chromatography system were compared to synthetic [Val5] and [lle5] angiotensin I, II and III. All three mouse angiotensins coincided with the corresponding synthetic [lle5] angiotensins during elution, suggesting the same type of angiotensin in mouse and man. An additional study on rat angiotensins confirmed previous findings by other investigators, indicating that the angiotensins of this animal were also of the [lle5] type.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

We activated three known components of the adenylate cyclase system in renal membranes from spontaneously hypertensive (SHR) and Wistar-Kyoto(WKY) rats. The basal adenylate cyclase activity and responses to plasma membrane receptor activation by parathyroid hormone, isoproterenol and vasopressin were not different between the two strains. The response to prostaglandin E2(PGE2), however, was less in the SHR than in the WKY at five, (P<0.05), 12 (P<0.01) and 16 (P<0.01) weeks of age. Activation of either the guanosine-5'-triphosphate (GTP) binding regulatory protein (N) with sodium fluoride (NaF) and guanyl-5'-yl-imidodiphosphate [Gpp(NH)p|, or the catalytic unit with manganese chloride (MnCI2) or forskolin were not different between the two groups. When the medullary and cortical plasma membrane adenylate cyclase responses were studied separately, the observed decreased response to PGE2(of SHR) was found to be entirely in the cortex. Also, the NaF response was reduced in the cortical region of the 12-week-old rats, a finding suggesting a possibility of a post receptor defect. These results show that there is a defective renal adenylate cyclase response specific to prostaglandin E2in SHR. This defect could be related to the development of hypertension, by changing the natriuretic and/or renal vasodilating effects of these prostaglandins.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID