A comparison between sphygmomanometer-based and ambulatory blood pressure monitoring in acute salt loading and depletion protocol

INTRODUCTION: Ambulatory blood pressure monitors have been used in salt loading and depletion protocols. However, the agreement between measurements made using ambulatory blood pressure monitors and those made with the sphygmomanometer has not been evaluated. OBJECTIVE: The objective of this study was to compare the concordance of the two methods of blood pressure measurements in protocols of acute salt loading and depletion. METHOD: Systolic blood pressure was measured using a sphygmomanometer at the completion of salt infusion (2 L NaCl 0.9 percent, 4 h) and salt depletion (furosemide, 120mg/day, p.o.) in 18 volunteers. Using the Pearson correlation coefficient (ρ), these readings were compared with the mean systolic blood pressure measured using the ambulatory blood pressure monitoring device during the following periods: 4 h of saline infusion and 12 h of salt depletion; 4 h of saline infusion and the last 6 h of salt depletion; 12 h of salt loading and the last 6 h of depletion; 12 h of salt loading and 12 h of depletion. Salt sensitivity was defined by a difference in the systolic blood pressure between salt loading and salt depletion greater than 10 mmHg when measured with the sphygmomanometer, and the Kappa analysis of concordance (K) was used with a significance level of P<0.05. RESULTS: Only the blood pressure readings obtained using the ambulatory blood pressure device during 4 h of intravenous NaCl and during 12 h of salt depletion showed a high correlation with the variation in the systolic blood pressure measured by the sphygmomanometer, with a full agreement with the salt sensitivity classification (p = 0.71; P = 0.001 and K=1). CONCLUSION: In acute salt loading and depletion protocols, an ambulatory blood pressure monitoring device should be used to record the blood pressure during the 4-h interval of salt infusion and 12-h interval of salt depletion.

Chronic salt-loading downregulates large-conductance Ca2+-activated potassium channel in mesenteric arterial smooth muscle cells from SD rats / 药物分析学报

Objective Large-conductance culcium-activated potassium (BKCa) channel modulates vascular smooth muscle tone. In the present study, we tested the hypothesis that salt, one of the factors which significantly influence bleed pressure (BP), can regulate BKCa activity and then elevate blood pressure. Methods Male Spragne-Dawley rats aged 6 weeks were randomized into high salt diet group (HS) and control group, fed with high salt diet (containing 5% NaCi) and standard rat chow (containing 0.4% NaCl) respectively for 16 weeks. Tail systolic blood pressure (SBP), body weight (BW) and 24-hour urinary output were tested every 4 weeks. Content of urinary Na+ was detected using flame spectrophotometrical method. At the end of 16 weeks, all the rats were killed, the mesenteric arteries were obtained, and single mesenteric smooth muscle cells were isolated at once. The resting membrane potential (Em), the total potassium currents and the currents after perfusion with TEA solution of the cells were all recorded by whole cell patch clamp. The transcriptions of BKCa channel α and β1 sobunits in mesenteric arterial vascular smooth muscle cells (VSMC) of each group were calculated by real-time RT-PCR. Results There was no difference in SBP and BW at each stage between control group and HS group; the urinary Na+ level in HS animals was elevated significantly after 4 weeks.The negative values of Em in HS group VSMCs were reduced compared with these in the control group. Transcriptions of β1 subanit of BKCa channels were decreased in HS group, but α subunit transcriptions did not differ between the two groups. Whole cell potassium currents did not differ hetween HS and control groups, but BKCa currents of HS group VSMCs were lower than these of control group ones. Conclusion Even without elevating SBP, salt-loading can still modulate the expression and activity of BKCa channel in the mesenteric arterial VSMC and elevate vascular tone.

Chronic salt-loading downregulates large-conductance Ca2+- activated potassium channel in mesenteric arterial smooth muscle cells from SD rats / 西安交通大学学报·英文版

Objective: Large-conductance calcium-activated potassium (BKCa) channel modulates vascular smooth muscle tone. In the present study, we tested the hypothesis that salt, one of the factors which significantly influence blood pressure (BP), can regulate BKCa activity and then elevate blood pressure. Methods: Male Sprague-Dawley rats aged 6 weeks were randomized into high salt diet group (HS) and control group, fed with high salt diet (containing 5% NaCl) and standard rat chow (containing 0.4% NaCl) respectively for 16 weeks. Tail systolic blood pressure (SBP), body weight (BW) and 24-hour urinary output were tested every 4 weeks. Content of urinary Na+ was detected using flame spectrophotometrical method. At the end of 16 weeks, all the rats were killed, the mesenteric arteries were obtained, and single mesenteric smooth muscle cells were isolated at once. The resting membrane potential (Em), the total potassium currents and the currents after perfusion with TEA solution of the cells were all recorded by whole cell patch clamp. The transcriptions of BKCa channel α and β1 subunits in mesenteric arterial vascular smooth muscle cells (VSMC) of each group were calculated by real-time RT-PCR. Results: There was no difference in SBP and BW at each stage between control group and HS group; the urinary Na+ level in HS animals was elevated significantly after 4 weeks. The negative values of Em in HS group VSMCs were reduced compared with those in the control group. Transcriptions of β1 subunit of BKCa channels were decreased in HS group, but α subunit transcriptions did not differ between the two groups. Whole cell potassium currents did not differ between HS and control groups, but BK Ca currents of HS group VSMCs were lower than those of control group ones. Conclusion: Even without elevating SBP, salt-loading can still modulate the expression and activity of BKCa channel in the mesenteric arterial VSMC and elevate vascular tone.

Study on Physiological Characteristics and the Association with Low Prevalence of Hypertension in "Desert People Population" in Taklimakan Desert / 医学研究杂志

Objective To investigate the physiological characteristics and the association with low prevalence of hypertension in "desert people" ,as an isolated population,in Taklimakan Desert.Methods All data were obtained from each person by questionnaire and standardized physical examinations. Total 469 subjects received examinations,including 359 subjects of "desert people" (M/F=205/154),aged from 15~99 years; 101 subjects of Uyghur from Yutian county (M/F=51/50),aged from 20~85 years,as controls. Some parameters :TC,TG,LDL-C,HDL-C,Apo-A,Apo-B,Lp-a,BUN,UA and CRE were determined. The statistical analysis was performed with SAS9.1.3 Version (Inititute Inc. Cary,NC. USA). Continuos values were expressed as mean?SD.Differences between groups were examined by student's t test,and statistical difference was considered when the P value was less than 0.05.Results 1)The height in "desert people" was significantly taller than that in controls.P value was 0.0317 for male and P60 years,P value was 0.0127 and 0.0443,respectively.(3)The prevalence of hypertension in "desert people" was 7%(24/359),that was significantly lower than that in controls(30.7%,31/101),P