Effects Of Chronic Salt Loading And Potassium Supplement On Morning Blood Pressure Surge In Primary Hypertensive Patients

BackgroundLarge amounts of study have demonstrated that hypertension is the result ofenvironmental and genetic factors working together, salt is one of the major factors.Different persons have different reaction to salt loading, which refers as salt-sensitivityand non salt-sensitivity. Salt-sensitivity is medial genetic phenotype and has asignificant relationship to cardiovascular event and crowd mortality. Cold pressure testis one of sympathetic nerve provocation tests; we can assess the sympathetic nervousactivity in primary hypertensive patients. Morning blood pressure surge means bloodpressure rising sharply in morning, often leading significantly increased cardiovasculardisease risk, more severe target organ damage, and independent of blood pressureaverage day and night.Apperance of morning blood pressure has a great relationshipwith abnormal regulatory mechanism. But the relationship among salt-sensitivity, saltloading and potassium supplement is still unclear, so investigating whether dietaryintervention can reduce the incidence of morning blood pressure surge havingimportant implications.Objective⑴To observe the situation ofsalt-sensitivity in rural hypertensive patients in ourcountry through chronic salt loading and potassium supplement test.⑵To investigate the relationship betweensalt-sensitivity and sympathetic nervousactivity.⑶To observe the relationship betweensalt-sensitivity and morning blood pressure surge, and the effect of chronic salt loading and potassium supplement to morningblood pressure surge.⑷To observe the relationship between blood pressure variation and morning bloodpressure surge.⑸To investigate the correlation between cardiovascular risk factors and morning bloodpressure surge.MethodWe used village as a unit, one whose age was16~60and systolic blood pressure was140~170mmHg and/or diastolic blood pressure90~100mmHg was enrolled. Age,height, weight and other general information were collected. They were divided intosalt-sensitivity group and non salt-sensitivity group according to chronic salt loadingand potassium supplement test. All the subjects received cold pressure test baselineperiod. Ambulatory blood pressure monitoring was used in every dietary interventionstage, they were divided into morning blood pressure group and non morning bloodpressure group.Results⑴The relevance ratio ofsalt-sensitivity is54.3﹪in primary hypertensive patientsaccording to Sullivan salt-sensitivity judgment standard; The systolic blood pressure,diastolic blood pressure and mean blood pressure were significant lower in low sodiumdietary stage than in baseline period, P＜0.01.After high sodium dietary, the level ofblood pressure significantly rises and drops in high sodium and potassium supplementstage. The variation in salt-sensitivity group was more significant than in nonsalt-sensitivity group, P＜0.01or P＜0.05;Most of general information has nostatistical differences between two groups except fasting blood sugar.⑵The positive rate of cold pressure testis47.6﹪in all subjects. There is goodrelativity between salt-sensitivity and cold pressure test, P＜0.01;Blood pressure risessignificantly in two groups after cold pressure test, higher than in resting stage, P＜0.05; The accessional range is significantly higher in salt-sensitivity group than in nonsalt-sensitivity group, P＜0.05. ⑶The incidence of morning blood pressure surge is53.7﹪in salt-sensitivity group,and37.4﹪in non salt-sensitivity group,P＜0.05;The average morning blood pressuresurge is41.0±16.6mmHg in salt-sensitivity group significantly higher than36.8±18.3mmHg in non salt-sensitivity group, P＜0.01.⑷The incidence of morning blood pressure surge in different dietary intervention stageis higher in salt-sensitivity group than in non salt-sensitivity group,P＜0.01.Theincidence and quantity of morning blood pressure surge was lower in low sodium stagethan in baseline period, P＜0.01;but higher in high sodium stage than in baseline period,P＜0.05or P＜0.01.⑸The incidence of morning blood pressure surge is56.9﹪in cold pressure testpositive subjects significantly higher than34.2﹪,P＜0.01;The quality of morningblood pressure surge is46.1±14.3mmHgmmHg in cold pressure test positive subjects higher than27.3±16.1mmHg in coldpressure test negative subjects, P＜0.01.⑹All subjects are divided into morning blood pressure group and non morning bloodpressure group according to the result of ambulatory blood pressure. The24h,daytime,nighttime systolic blood pressure,pulse pressure and mean blood pressureare significantly higher in morning blood pressure group than in non morning bloodpressure group, P＜0.05;The24h, daytime, nighttime diastolic pressure have nodifference between two groups, P＞0.05. The24h, daytime, nighttime blood pressurevariability is more significant in morning blood pressure group than in non morningblood pressure group, P＜0.01or P＜0.05;⑺The Pearson relation analysis between morning blood pressure surge and bloodpressure variation shows that morning blood pressure surge positively correlated with24h SBP-SD and nDBP-SD(r=0.340,0.217,both P＜0.01);Multiple linear regressionsshows that age,24h SBP-SD, fasting blood sugar and nDBP-SD are impendent riskfactors for morning blood pressure surge.⑻The Pearson relation analysis between morning blood pressure surge andcardiovascular disease risk factors shows that morning blood pressure surge positively correlated with age,24hSBP and fasting sugar,(r=0.567,0.347,0.388,all P＜0.01);Andthere are no statistical differences man and female, P=0.204; Multiple linearregressions shows that age,24hSBP, fasting blood sugar are impendent risk factors formorning blood pressure surge.Conclusion⑴Salt is an important factor for the occurrence and development of primaryhypertension,there is high relevance ratio of slat-sensitivity in primary hypertensivepatients; In these patients, salt loading can significantly raise blood pressure and saltrestricting, potassium supplement can significantly lower blood pressure, reduce targetorgan damage caused by high blood pressure.⑵Salt-sensitivity hypertensive patients have a higher cold pressure test positive rate;Salt-sensitivity has certain relationship with abnormal activity of sympathetic nerve.⑶Salt-sensitivity and cold pressure test positive subjects have higher incidence ofmorning blood pressure surge, increasd activity of sympathetic nerve is one ofmechanism of morning blood pressure surge.⑷Morning blood pressure surge has a great relationshipwith target organ damage,independent of the level of24h blood pressure; Blood pressure variation significantlycorrelates with morning blood pressure surge; age, fasting blood sugar and24h SBP aremajor risk factors of morning blood pressure surge.