Showing papers by "Josep Redon published in 1994"

Ambulatory blood pressure and microalbuminuria in essential hypertension: role of circadian variability.

Abstract: ObjectiveTo assess the relationship of subclinical urinary albumin excretion with ambulatory and circadian variability of blood pressureDesign and methodsPatients with essential hypertension (82 males and 59 females, mean + SD age 389 ±73 years) who had never been previously treated for hypertens

Ambulatory blood pressure monitoring in normotensive children.

Abstract: OBJECTIVE To assess reference values of ambulatory blood pressure in normotensive children. SUBJECTS AND DESIGN Twenty-four-hour non-invasive ambulatory blood pressure monitoring (ABPM) was carried out in 241 healthy normotensive children aged from 6 to 16 years (126 boys, mean +/- SD age 11.2 +/- 2.7 years; 115 girls, mean +/- SD age 10.9 +/- 2.9 years). The subjects were subdivided into three age-sex groups: 6-9, 10-12 and 13-16 years. SETTING Primary care. MAIN OUTCOME MEASURES ABPM was performed using an oscillometric device (SpaceLabs model 90207) and appropriate cuff size during a regular school day. Blood pressure was measured every 20 min from 0600 to 2400 h, and thereafter every 30 min. At each monitoring session the following parameters were calculated for both systolic (SBP) and diastolic blood pressure (DBP): means and centiles for 24-h, daytime (0800-2200 h) and night-time (2400-0600 h); circadian variability, estimated as the blood pressure fall between the day and the night periods and the day: night ratio; and load, as the percentage of measurements above the age- and sex-specific 95th centile (P95). RESULTS The upper limits of 'normality' for the mean of 24-h SBP and DBP estimated as the P95 in each age subgroup were 121/71 and 119/71 mmHg, 123/78 and 120/74 mmHg, and 124/78 and 125/75 mmHg, for boys and girls, respectively. A progressive increase in SBP with age was observed in both sexes, in contrast, DBP was similar throughout the age range. A nocturnal blood pressure fall of approximately 11 mmHg was observed for both SBP and DBP in all subgroups. The day:night ratio was 1.12 and 1.22 for SBP and DBP, respectively. The upper limit of blood pressure load, estimated as the P95 in all children, was 39% for SBP and 26% for DBP. A significant positive correlation was observed between casual blood pressure and 24-h ambulatory blood pressure (SBP: r = 0.61, P < 0.0001; DBP: r = 0.31, P < 0.0001). In general, mean ambulatory blood pressure, during the 24-h or the daytime period, was higher than casual blood pressure for both SBP and DBP. CONCLUSION ABPM is feasible in children, and the values obtained are useful as a departure point in establishing reference values.

Regulation of intracellular pH in the spontaneously hypertensive rat: Role of bicarbonate-dependent transporters

Abstract: Previous studies that have evaluated the Na(+)-H+ antiporter in cells from hypertensive subjects were generally performed under conditions in which HCO3-CO2, the physiological buffer system, was absent from the assay media. The objective of this study was to evaluate the activity of the Na(+)-H+ antiporter and that of the Na(+)-dependent and Na(+)-independent Cl(-)-HCO3- exchangers in cells assayed in the presence of HCO3-CO2 in the media. Lymphocytes from 6- to 8-week-old spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats were obtained from the thymus gland and assayed immediately after isolation. The activity of the Na(+)-H+ antiporter after stimulation by cell acidification (pHi approximately 6.4) was similar in SHR and WKY rats (18.67 +/- 1.03 and 16.12 +/- 0.92 mmol H+/L per minute, respectively). Recovery from cell alkalinization was effected by an Na(+)-independent Cl(-)-HCO3- exchanger, with maximal activity at an alkaline pHi (approximately 7.7). The stimulated activity of this Na(+)-independent Cl(-)-HCO3- exchanger was also not different between SHR and WKY cells (2.65 +/- 0.25 and 2.55 +/- 0.32 mmol H+/L per minute, respectively). Acute chloride removal produced a rise in pHi that was Na(+)-dependent and sensitive to 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) but resistant to ethylisopropylamiloride (EIPA), reflecting the activity of an Na(+)-dependent Cl(-)-HCO3- exchanger. Unlike the Na(+)-H+ exchanger and the Na(+)-independent Cl(-)-HCO3- exchanger, which had their highest activities at extremes of pHi (low pHi, Na(+)-H+ exchanger, and high pHi, Na(+)-independent Cl(-)-HCO3- exchanger), the Na(+)-dependent Cl(-)-HCO3- exchanger had its maximal activity near steady-state pHi (approximately 7.1). No significant differences were found in the stimulated activity of this exchanger between cells from SHR and WKY rats (2.23 +/- 0.26 and 2.50 +/- 0.43 mmol H+/L per minute, respectively). The kinetic properties of the Na(+)-dependent and Na(+)-independent Cl(-)-HCO3- exchanger, examined as a function of external Cl-, were also virtually identical in cells from SHR and WKY rats. We conclude that in lymphocytes from SHR and WKY rats, the activity of the two Cl(-)-HCO3- exchangers, like that of the Na(+)-H+ exchanger, is dependent on the prevailing pHi. The Na(+)-dependent Cl(-)-HCO3- exchanger has its highest activity near steady-state pHi, suggesting an important role in the cell defense against intracellular acidosis under physiological conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid-base status and intracellular pH regulation in lymphocytes from rats with genetic hypertension.

Abstract: This article reviews work from this laboratory dealing with acid-base status and intracellular pH (pHi) regulation in rat genetic models of hypertension. With freshly isolated thymic lymphocytes, pHi and its regulation were examined in the spontaneously hypertensive rat (SHR). In this rat model, pHi was found to be reduced as compared with that of lymphocytes from normotensive Wistar-Kyoto (WKY) rats. The activity of the Na+/H+ antiporter assessed after stimulation by acute cell acidification was similar in lymphocytes from SHR and WKY rats both in the nominal absence of HCO3- and in media containing HCO3- (22 mM). The kinetic properties of the Na+/H+ antiporter, examined as a function of pHi with the Hill kinetic model, revealed no significant differences between lymphocytes from SHR and WKY rats. The kinetic properties of the Na(+)-dependent and Na(+)-independent Cl(-)-HCO3- exchangers, examined as a function of external Cl-, were also virtually identical in lymphocytes from SHR and WKY rats. Unlike the Na(+)-H+ exchanger and the Na(+)-independent Cl(-)-HCO3- exchanger, which had their highest activities at extremes of pHi (low pHi, Na(+)-H+ exchanger; high pHi, Na(+)-independent Cl(-)-HCO3- exchanger), the Na(+)-dependent Cl(-)-HCO3- exchanger had its maximal activity near steady-state pHi. In Dahl/Rapp salt-sensitive rats with hypertension, the pHi of thymic lymphocytes was also reduced as compared with that of normotensive salt-resistant animals. In this model, renal net acid excretion in salt-sensitive rats was augmented as compared with that of salt-resistant rats. The increase in renal acid excretion was due to an increase in both ammonium and titratable acid excretion and was observed while animals were placed on high, normal and low salt diets. The findings of intracellular acidosis and enhanced renal acid excretion suggest that cellular acid overproduction is augmented in salt-sensitive hypertension.

An evaluation of the control of antihypertensive treatment by using ambulatory arterial pressure monitoring

Abstract: BACKGROUND Outpatient monitoring of blood pressure (OPMBP) allows more precise values to be obtained and to observe the oscillations over 24 hours. Although this is widely used in the estimation of the antihypertensive efficacy of drugs, few studies have been performed on the evaluation of the control in treated patients. METHODS One hundred eight patients (M/F 55/53, mean age 50 +/- 11 years, body mass index 29.7 +/- 4.4) with essential high blood pressure (HBP) were included in the study fulfilling the criteria of: a) DBP > 95 mmHg on 3 visits over a 2 month period, b) antihypertensive treatment maintained over 2 months and c) normal renal function (Cr 150/100 mmHg during the course of treatment with well combined and adequately dosed drugs, one of which was a diuretic. Twenty-four hour OPMBP was carried out in all the patients on a normal work day with a SpaceLabs 90202 monitor. Acceptable control was considered when the mean of the DBP throughout the day (08:00-22:00) was < 85 mmHg. RESULTS Out of all the patients studied, 67 (62%) showed acceptable control and 27 (25%) showed normotensive values. Among the 25 refractory hypertensive patients 20 (40%) showed an acceptable control and 7 (28%) normotensive values. The only clinical difference between both groups was the presence of a greater degree of organic repercussion in the inadequately controlled group (chi 2 p < 0.05). Eight patients showed medium values of SBP over 24 h < 120 mmHg and 2 medium values of DBP over 24 h < 70 mmHg. CONCLUSIONS Outpatient monitoring of blood pressure may be useful in the evaluation of the control of high blood pressure in patients submitted to pharmacologic treatment who do not present an adequate reduction in the values of blood pressure.