ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The relationships between five erythrocyte cation transport systems (Na+-K+pump, Na+-K+cotransport, Na+-Li+countertransport and Na+and K+passive permeabilities) and plasma lipids (total plasma cholesterol, high-density lipoprotein cholesterol and triglycerides) were investigated in 129 male adult subjects with no known history of hypertension. Na+and K+erythrocyte contents were also considered for their possible relationships with plasma lipids. Na+-K+cotransport and passive Na+permeability were both significantly correlated with plasma triglycerides. Conversely, no significant correlation was found between erythrocyte cation transport systems or erythrocyte cation contents and total cholesterol. These findings suggest that plasma lipids can modulate erythrocyte ion transport activity in the general population.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effects of prostaglandin E2(PGE)2and the thromboxane A2(TxA2) receptor agonist U-46619 on noradrenaline release and pressor responses to renal nerve stimulation (RNS) at 1 Hz were investigated in isolated kidneys of spontaneously hypertensive rats (SHR; 5–7 weeks) and age-matched Wistar–Kyoto rats (WKY). After incubation with3H-noradrenaline, the renal nerves were stimulated. The stimulation-induced (S-l) outflow of radioactivity was taken as an index of noradrenaline release. Absolute S-l outflow of radioactivity was lower in SHR than in WKY but pressor responses to RNS were greater in SHR than in WKY. Tetrodotoxin (1 µmol/l) abolished S-l outflow of radioactivity and pressor responses to RNS in both strains. PGE2(0.06 µmol/l) inhibited S-l outflow of radioactivity in SHR but not in WKY kidneys. PGE2(0.6 µmol/l) inhibited S-l outflow of radioactivity in both strains. In SHR, PGE2(0.6 µmol/l) decreased pressor responses to RNS, but increased them in WKY. In WKY, but not in SHR kidneys, pressor responses to RNS were markedly reduced by the &U0251;1-adrenoceptor antagonist prazosin (0.1 µmol/l). The prazosin-resistant pressor responses to RNS were blocked by &U0251;,ß-methylene adenosine triphosphate (ATP; 1 µmol/l). In kidneys of SHR, pretreated with 6-OH-dopamine (50 mg/kg intravenously, 24 and 48h before isolation of the kidneys) to destroy sympathetic nerve endings, pressor responses to RNS and S-l outflow of radioactivity were almost abolished. U-46619 (0.1 µmol/l) increased perfusion pressure in SHR and WKY kidneys and this effect was blocked by the TxA2receptor antagonist daltroban (BM 13505; 3µmol/I). U-46619 did not significantly modulate S-l outflow of radioactivity. The results suggest that activation of prejunctional PGE2receptors in kidneys of SHR and WKY inhibits noradrenaline release. The prejunctional inhibitory PGE2receptor mechanism on renal sympathetic nerves seems to operate more effectively in SHR than in WKY. There is no evidence for prejunctional TxA2receptors in the kidneys of SHR or WKY. Pressor responses to RNS at 1 Hz in SHR kidneys seem to be due entirely to release of a purinergic co-transmitter from renal sympathetic nerves, and PGE2possibly reduces pressor responses to RNS by inhibiting release of this purinergic co-transmitter.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The heating and restraint inherent to tail-cuff measurement of systolic blood pressure (SBP) in rats may alter SBP and introduce a 'biological' error in its estimation by this technique. This problem was examined in unanesthetized normotensive and hypertensive rats fitted with an arterial catheter. All SBP values recorded in unrestrained rats during a 2 h period were averaged by computer and compared with intra-arterial SBP measurements observed white the rat was being subjected to the tail-cuff procedure. With the latter procedure, SBP was 16 ± 2mmHg lower in normotensive rats (P<0.01) and 7 ± 3 mmHg higher in hypertensive rats (P<0.05) than when the rats were unrestrained. The effects of heat and restraint, both separately and in combination, on SBP were evaluated during four additional 30-min monitoring periods. In both groups of rats, restraint failed to alter SBP and heat lowered it slightly. The two stimuli, combined, lowered SBP in normotensive rats, but raised it by 12 ± 2 mmHg in hypertensive rats (P<0.01). Thus, tail-cuff SBP measurements represent under- and overestimates in normotensive and hypertensive rats, respectively, since the two groups respond to the procedure in opposite manners.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Office, i.e. measured by the physician at rest, and 24h ambulatory systolic (SBP) and diastolic (DBP) blood pressures, heart rate, supine and upright plasma renin activities, supine and upright aldosterone concentrations and plasma and urine sodium and potassium were measured in 61 young male subjects aged 19–25 years, including 40 normotensive subjects (office DBP ≤90mmHg and office SBP ≤140mmHg) and 21 borderline hypertensive subjects (non-normal blood pressures with office DBP ≤95mmHg and office SBP ≤160mmHg). No significant differences were found in the plasma or urine K+ or Na+, upright or supine plasma renin activity or aldosterone concentration between normotensives and borderline hypertensive subjects. No correlation was detected between plasma and urine K+ or Na+, upright and supine aldosterone concentration or supine plasma renin activity and blood pressure. In contrast, significant inverse correlations were observed between upright plasma renin activity and blood pressure. The correlations were approaching statistical significance when upright plasma renin activity was related to office SBP and office DBP (r=-0.22,P=0.097 andr=- 0.25,P=0.049, respectively), and were more significant when plasma renin activity was related to 24h mean DBP (r=-0.32,P=0.013) and to SBP and DBP standard deviations (r=-0.37,P=0.004 andr=-0.26,P=0.04, respectively). The correlations were highly significant when upright plasma renin activity was related to the SBP and DBP day–night fluctuation, the latter being calculated by the cosinor model (r=-0.37,P=0.003 andr=-0.43,P=0.001, respectively). The results suggest that plasma renin activity may already be involved in borderline essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

We have attempted to characterize the as yet unspecified circulating factor(s) in spontaneously hypertensive rat (SHR) serum that elevate(s) the cytoplasmic calcium ion concentration in vascular smooth muscle cells (VSMC). We measured the cytoplasmic calcium ion concentration in cultured VSMC before and after incubation with serum from SHR or Wistar–Kyoto rats (WKY). Incubation with serum from overtly hypertensive 8-week-old SHR, but not with serum from 8-week-old WKY, significantly elevated the cytoplasmic calcium ion concentration in VSMC from 8-week-old WKY and 4-week-old SHR in a dose- and an incubation period-dependent manner, although no significant elevation occurred in VSMC from 4-week-old WKY. Neither the heat-immobilized nor the trypsinized 8-week-old SHR serum elevated the cytoplasmic calcium ion concentration. Ultrafiltration procedures indicated that the molecular weight of the factor should be 10 000-30 000 daltons. Incubation with serum from 4-week-old SHR or WKY did not elevate the cytoplasmic calcium ion concentration. These results strongly suggest that: (1) a cytoplasmic calcium ion concentration elevating factor exists in serum from 8-week-old SHR but not from 4-week-old SHR, or 4- or 8-week-old WKY; (2) this factor should be of a protein nature, with a molecular weight of 10 000–30 000 daltons; (3) responsiveness to the factor appears in VSMC at a younger age in SHR than in WKY; (4) the factor elevates the cytoplasmic calcium ion concentration to the level determined a priori not by the strain but by the age of the rats from which the VSMC originate; and (5) the a priori determined level increases with the age of the rats.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

When a human kidney is transplanted, sympathetic nerves to that kidney are cut. We infused3H-noradrenaline and then measured noradrenaline, dopamine and3H-noradrenaline levels in the plasma and urine of renal transplant recipients and uninephrectomized control subjects. Less than 10% of3H-noradrenaline cleared from the plasma appeared in the urine. Noradrenaline and dopamine appeared in the urine of transplant recipients at one-third the rate of control subjects, even though3H-noradrenaline levels were slightly higher in the urine of transplant recipients. Transplant patients had a noradrenaline clearance of 128 ± 50ml/min, compatible with simple glomerular filtration, while controls had a higher calculated clearance of 229 ± 41 ml/min. Plasma dopamine levels were very low compared with urinary dopamine. These results suggest that two-thirds of renal noradrenaline and dopamine depend on the presence of renal nerves. Almost all urinary dopamine comes from the kidney. For noradrenaline, urinary excretion is a very minor pathway for clearance from the plasma.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Tortuosity, dilations, aneurysms and satellite hemorrhages consistently develop in the circular arteries of the iris of rabbits with acute one-kidney, one clip (1K1C) malignant hypertension. These lesions are easily visualized, quantitated and monitored during life. Graded iridoarteriopathy correlates directly with visceral arterial necrosis (r15=0.843; P<0.001), final indirect blood pressure (r15=0.591; P<0.02) and cardiac hypertrophy (r15=0.565; P<0.02). Arterial necrosis in the irises and other viscera in acute 1K1C hypertension in rabbits is qualitatively similar to that occurring in rabbits with acute one-kidney, one wrapped (1K1W) hypertension with regard to both the histological features and organ distribution. However, over three times as many arterial lesions occur in rabbits with acute 1K1W hypertension as occur in those with acute 1K1C hypertension (P<0.001). Since blood pressure elevation does not correlate with graded iridoarteriopathy or with visceral arterial necrosis in 1K1W rabbits, factors other than blood pressure elevation appear to be especially important in the pathogenesis of arterial necrosis in the 1K1W model. On the other hand, the present study indicates that high grade iridoarteriopathy appears to be indicative of a high risk of cerebral hemorrhage in 1K1C rabbits, as earlier studies have shown for 1K1W rabbits.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To evaluate cardiac structure and function as well as blood pressure in the obstructive sleep apnoea syndrome (OSAS), we investigated 61 male patients and 61 male controls with M-mode and two-dimensional echocardiography. All patients had a history of habitual snoring and a diagnosed light to severe OSAS by previous investigations of nocturnal oxygen saturation status. No subject in the control group had a history of OSAS or hypertension. Body weight was higher in the OSAS patients than in the controls (P<0.001). Fifty per cent (31 out of 61) of the OSAS patients had systemic hypertension; 17 of these 31 were on pharmacological antihypertensive treatment. Neither the systolic nor the diastolic blood pressures were found to correlate to the severity of the OSAS (desaturation index). The heart rate was higher at rest in the OSAS patients with or without systemic hypertension compared to the controls with or without a blood pressure level above 165/95 mmHg (P<0.05 andP<0.01, respectively). Left ventricular (LV) internal dimensions as assessed by echocardiography did not differ between the two groups, while the interventricular septum and the LV posterior wall were thicker in the OSAS group. Thus, the LV mass and the LV mass index were significantly higher among the OSAS patients (P<0.001 andP<0.001). The LV mass index was approximately 15% higher among the 30 normotensive OSAS patients with no history of cardiac disease compared with the normotensive controls (P<0.05). Patients and controls without antihypertensive treatment, matched by weight (n=20), had different LV mass (259 ± 12 versus 221 ± 8g, P=0.01), despite there being no difference in the daytime blood pressure. The ejection fraction and the left atrial dimension did not differ between patients and controls. Measures of LV structure or function were not correlated to the severity of the OSAS as depicted by desaturation index or minimal nocturnal oxygen saturation during nocturnal investigations. Thus, both systemic hypertension and LV hypertrophy seem to be common phenomena in OSAS. We did not find the severity of OSAS to be predictive of systemic hypertension or LV structural changes. Also, OSAS patients without hypertension had LV hypertrophy, the development of which may be partly due to other pathophysiological mechanisms.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID