摘要:

SUMMARY1. Two groups of age‐ and sex‐matched subjects, eight healthy controls and 10 patients, suffering from recurrent vasodepressor syncope, participated in a study to examine autonomic function and sequential changes in power distribution of heart rate (HR) variability during graded head‐up tilt.2. The following autonomic function tests were performed valsalva ratio, HR responses to deep breathing and posture, BP responses to sustained handgrip and postural change. Each subject was tilted at 15°, 30°, 45°, 60° and 80° head‐up, each for 15 min, or until symptoms occurred. The eight control subjects completed the tilt study without any symptoms, while all 10 patients developed presyncope and/or syncope at various tilt angles.3. Resting blood pressure (BP) was lower in the patient group, while resting HR, autonomic function tests and resting HR variability components were similar in the two groups.4. The control group showed a progressive increase in low frequency power component (LF) from supine to end tilt (ΔLF 20.06 ± 14.50%) and a progressive fall in high frequency (HF) component (ΔHF—24.62 ± 10.64%). In contrast, in the patient group, LF fell during tilt in the presyncope period (ΔLF ‐10.57 ± 12.93%,P<0.01vscontrol group). HF and HF: LF ratio responses did not differ significantly in the two groups.5. At end tilt, the increase in plasma noradrenaline was significantly greater in the control group than in the patient group (ΔNA 0.83 ± 0.27 vs 0.28 ± 0.14 pmol/mL,P<0.01). Plasma adrenaline: noradrenaline ratio at end tilt did not change in the control group, but increased significantly in the patient group (supine 0.07 ± 0.03, end tilt 0.16 ± 0.09,P<0.05).6. It was concluded that sympathetic withdrawal plays a major role in the mechani

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02048.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. In five intact rabbits β‐adrenoreceptor blockade (i.v. propranolol), and combined cardiac blockade (i.v. propranolol plus i.v. methscopolamine sulphate) revealed that spectral power of heart rate (HR) variability at low frequencies (LF: 0.0625–0.1875 Hz) was modulated predominantly by the sympathetic nervous system and power at high frequencies (HF: 0.4373–0.5625 Hz) by vagal influences.2. In 16 rabbits resting power of HR at LF and changes in LF power in response to maximal treadmill exercise were examined prior to and after 4 and 6 weeks of doxorubicin treatment (1 mg/kg twice weekly).3. The development of doxorubicin‐induced congestive heart failure (CHF) was accompanied by a progressive increase in resting LF power [control, 8.5 ± 2.1; 4 weeks, 13.4 ± 1.8; 6 weeks, 21.9 ± 3.5 (beats/min)2,P0.05] whereas CHF rabbits showed falls in LF power after 4 weeks [4.6 ± 1.0 vs 13.4 ± 1.8 (beats/min)2,P<0.005] and 6 weeks [6.5 ± 2.4vs21.9 ± 3.5 (bents/min)2,P<0.005] of doxorubicin treatment.5. It was concluded that PSA of HR variability reflects the autonomic regulation of sinus node function in conscious rabbits. In doxorubicin‐treated animals, the rise in LF power reflects increased sympathetic activity as CHF develops. However, the apparent paradoxical fall in LF power with exercise in these animals underscores the need for caution in interpret

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02049.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. The levels of the neurotrophic factor, nerve growth factor (NGF) in the mesenteric vascular bed of the spontaneously hypertensive rat (SHR) were greater than those in the corresponding vascular bed of normotensive Wistar‐Kyoto rats (WKY).2. Administration of angiotensin II (200 ng/kg per min, by minipump) for 2 weeks to juvenile WKY rats increased the levels of NGF in the mesenteric vasculature to those seen in untreated SHR.3. Administration of the angiotensin II receptor antagonists losartan (30 mg/kg per day, p.o.) or PD144277 (10 mg/kg per day, p.o.) to juvenile SHR for 4 weeks reduced the levels of NGF such that they were indistinguishable from the values obtained for normotensive WKY rats.4. The results confirm the elevated level of NGF in the mesenteric vasculature of the SHR and suggest that angiotensin II may play a role in regulating the abnormal concentrations of the protein in this tissu

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02050.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. In the present study we have examined the effects of angiotensin I converting enzyme (ACE) inhibition and nitric oxide (NO) synthesis inhibition on bradykinin (BK) depressor responses in pregnancy in both Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR).2. Ramipril (10 mg/kg, i.v.) significantly reduced mean blood pressure (MBP) in all animals. Further administration of L‐nitro‐arginine (L‐NOARG, 20 mg/kg, i.v.) increased MBP to a less extent in pregnant WKY and to a similar level in pregnant SHR compared with their non‐pregnant controls (controls), respectively.3. Systemic depressor responses to BK were increased in pregnant WKY and were unchanged in pregnant SHR as compared with their controls. Ramipril (10 mg/kg, i.v.) potentiated BK responses in all groups, and abolished the differences between pregnant and non‐pregnant WKY. Further administration of L‐NOARG (20 mg/kg, i.v.) did not further influence BK responses in all groups.4. The results suggest that systemic depressor responses to BK are enhanced in pregnant WKY and unchanged in pregnant SHR. Decreased ACE activity may contribute to enhanced systemic depressor responses to BK in

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02051.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. Angiotensin‐responsive aldosterone‐producing adenomas (AII‐R‐APA) have increased expression of renin mRNA compared with angiotensin‐unresponsive aldosterone‐producing adenomas (AII‐U‐APA) or normal adrenals.2. Further, significant associations between theBglI,TaqI andHinfI RFLP and aldosterone responsiveness to the renin‐angiotensin system of the two subgroups of patients have been reported.3. Using the polymerase chain reaction based technique single stranded conformational polymorphism, we detected no alterations in exon 1 of the renin gene in peripheral blood leucocyte DNA from normal AII‐U‐APA and AII‐R‐APA subjects.4. Using long‐PCR, we amplified a fragment of the renin gene consisting of a region covering 500 bp upstream of exon 1, exon 1 and intron A. No gross changes in this area of the renin gene were found in the three groups of subjects studied. However this does not exclude sma

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02052.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. External compression of the human brachial artery results in waveform reflection.2. Resonant waves are found superimposed on the original blood pressure signal.3. The mechanism may be likened to the operation of an organ pipe with reflections at both ends of an arterial segment.4. This has implications for measurements in arteries where external pressure is applied.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02053.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. In a 19 month period from June 1993 to December 1994, 60 patients (mean age 54.8 ±.5 years s.e.m.; 32 males, 28 females) underwent unilateral laparoscopic adrenalectomy by one of us (JCR) for the treatment of hypertension due to primary aldosteronism (n = 48), phaeochromocytoma (n = 3) and cortisol‐producing adenoma (n = 1) or to remove adrenal masses incidentally discovered on abdominal computerized tomography scanning (‘incidentaloma’) performed for other reasons (seven adenomas without biochemical evidence of excessive steroid hormone or catecholamine secretion and one carcinoma autonomously producing cortisol).2. Compared with conventional open procedures, laparoscopic adrenalectomy was associated with reduced recovery time and a low complication rate (one pulmonary embolus and one port site incisional hernia).3. Operation time with experience approximates that of open procedures (60 min), but is significantly longer in obese than in non‐obese patients, and in males than in females.4. Patients with adrenal causes of hypertension were cured or significantly improved by laparoscopic unilateral adrenalectomy.5. Because of our concern regarding malignant potential of incidentalomas and high patient acceptance of laparoscopic techniques, we have reduced our size criteria for removal of incide

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02054.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. Renin mRNA is expressed in several extrarenal tissues, including brain. The aim of the present study was to quantify renin mRNA in the hypothalamus in response to a low NaCl diet and angiotensin converting enzyme inhibitor treatment, both of which are well‐known stimuli of renin mRNA in kidney.2. Groups of six Sprague‐Dawley rats were given either a normal diet, low NaCl chow (0.04% NaCl), enalapril (0.25 mg/mL in drinking water), or low NaCl + enalapril, for 7 days. Renin mRNA in the hypothalamus was quantified by a competitive reverse transcriptase‐polymerase chain reaction (RTPCR) technique.3. Renin mRNA concentration in the hypothalamus of rats receiving a normal diet was 52 ± 3 S.E. fg/μg total RNA. Low NaCl had no effect (57 ± 7), whereas values were significantly lower in rats treated with enalapril, either given alone (38 ± 2;P= 0.002) or combined with a low NaCl diet (33± 4;P= 0.003).4. In conclusion, we have quantified renin mRNA in the rat hypothalamus and shown that it can be suppressed significantly by enalapril. This response is opposite to that seen in the kidney after

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02055.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARY1. The low density lipoprotein receptor is an important regulator of serum cholesterol which may have implications for the development of both hypertension and obesity. In this study, genotypes for a low density lipoprotein receptor gene (LDLR) dinucleotide polymorphism were determined in both lean and obese normotensive populations.2. In previous cross‐sectional association studies anApaLI and aHincII polymorphism forLDLRwere shown to be associated with obesity in essential hypertensives. However, these polymorphisms did not show an association with obesity in normotensives.3. In contrast, this study reports that preliminary results for anLDLRmicrosatellite marker, located more towards the 3’ end of the gene, show a significant association with obesity in the normotensive population studied. These results indicate thatLDLRcould play an important role in the development of obesity, which might be independent of hypertens

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1995.tb02056.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY