한국 정상인 및 본태성고혈압 환자에 있어서의 Na+대사에 관한 연구

Abstract

[한글]

The Dynamic Aspect of Sodium Metabolism in Both Healthy Koreans and Patients with

Essential Hypertension

Kap Bum Huh, M.D.

Department of Medical Science The Graduate School, Yonsei University

(Directed by Prof. Eung Suk Chai)

Systemic studies on the sodium metabolism and various renal functions of healthy

Koreans were conducted by Hong et al. (1967), Lee et al. (1952) and Kim et al.

(1965) One of the outstanding characteristics is that they live on a low protein

and high salt diet.

Although contributing factors to hypertension have not been clearly elucidated,

dietary salt intake has been considered one of the most possible factors (Ambard

and Beaujard, 1904; Dahl and Love, 1957). In addition. an alteration in water and

salt metabolism in essential hypertension is generally well known (Baldwin et al.,

1559; Cottier et al., 1958; Green et 3l., 1954).

Since Goldblatt et al. (1934) observed an important role of the ischemic kidney

in renal hypertension, extensive efforts have been focused in isolating the pressor

substance and now it is well known as angiotensin(Page and Helmer, 1939; Skeggs et

al., 1956). Currently, the retrain-angiotensin system has been the subject of a

study for its physiological role in renal functions and sodium metabolism because

it can cause a change in the renal hemodynamics as a result of constricting

vascular smooth muscle (Gross and Bock. 1962; Helmer, 1964) and effects the sodium

transport in the renal tubule directly (Laragh et al., 1953) and indirectly through

a regulatory mechanism of aldosterone secretion (Davis et al., 1961; Genest, 1961).

In view of sodium regulatory factors in man mentioned above and high sodium

intake in the Koreans, it is worthwhile to study the dynamic aspect of sodium

metabolism by measuring the turnover rate and the amount of exchangeable sodium

along with the secretory activity of hormones such as aldosterone and

lenin-angiotensin. Furthermore it is expected to get some insight into the

pathogenesis of essential hypertension by comparing the results obtained from

patients with essential hypertension to those of healthy Koreans.

Materials and methods

Normal volunteers (medical students) and patients with uncomplicated essential

hypertension, 10 subjects from each group, were selected for this studs. An

ordinary Korean diet (high salt diet) was supplied and medications, if any, were

discontinued at least one week prior to this study. Salt intake was then reduced to

less than 5 gm. per day for a period of 5 days.

Plasma lenin activity (PRA) and the amount of urinary aldosterone excreted in 24

hours were measured on the 3rd day of high sodium intake and on the 5th day of the

low sodium regimen.

By repeating all of the above schedules, the total exchangeable body sodium store

and it's turnover rate were determined in the corresponding periods of plasma lenin

activity and urinary aldosterene measurements.

PRA was measured by radioimmunoassay method of Haber et .al. (1969), and urinary

aldosterone excretion was determined by double isotope derivative assay method of

Kliman and Peterson(1960).

Total exchangeable body sodium store and the turnover rate were measured with

(22)**Na by the method of Adesman et al. (1960).

Results and conclusions

1) The mean blood pressures of both control and hypertensive groups were

significantly decreased after 5 days of low salt diet compared to those checked

haying a normal diet.

2) PRA for the control group was significantly elevated after sodium restriction

compared to that found having a high salt diet. On the contrary, PRA for the

hypertensive patients was not significantly increased with sodium restriction.

Regardless of high or low sodium intake, PRA measured in the control group was

significantly higher than that found in the hypertensive group.

3) OR the high salt diet, Urinary aldosterone excreted in 24 hours was not

Significantly different between the healthy and the hypertensive groups. However,

the amount of daisy urinary aldosterone excretion in both groups was significantly

increased after the administration of a low salt diet. This increase of urinary

aldosterone excretion was particularly remarkable in the hypertensive group.

4) Plasma sodium concentrations measured in both groups were not significantly

changed regardless of high or low sodium intake.

5) The amount of daily urinary sodium excretion in the hypertensive patients was

significantly higher than that measured in the control group on a liberal Korean

diet. On the other hand, there was no significant difference in the daily urinary

sodium excretion between the two groups on sodium restriction.

6) PRA measured in the control group was inversely correlated with the daily

urinary sodium excretion, but the patient group showed persistently low PRA

regardless of high or low urinary sodium excretion. On the other hand, daily

urinary aldosterone excretions in both control and patient groups were inversely

correlated with urinary sodium excreted in 24 hours.

7) The total exchangeable body sodium stoles were net significantly different

between the control and the hypertensive patient groups regardless of high or low

sodium intake. On the contrary, the disappearance rate of plasma (22)**Na in

hypertensive patients during low sodium diet revealed somewhat an accelerated

tendency in comparison with that found in normal subjects.

In view of the above experimental findings, the regulatory mechanism of

aldosterone secretion in the patients with essential hypertension may be different

from that of the control group. That is, the retrain-angiotensin system in the

hypertensive patients may play a minor role in the regulation of aldosterone

secretion compared to normal subjects.

Furthermore it is speculated that the sensitivity of renal tubules to aldosterone

in patients with essential hypertension is reduced compared to that of normal

Korean healthy subjects.

[영문]

Systemic studies on the sodium metabolism and various renal functions of healthy Koreans were conducted by Hong et al. (1967), Lee et al. (1952) and Kim et al. (1965) One of the outstanding characteristics is that they live on a low protein

and high salt diet.

Although contributing factors to hypertension have not been clearly elucidated, dietary salt intake has been considered one of the most possible factors (Ambard and Beaujard, 1904; Dahl and Love, 1957). In addition. an alteration in water and salt metabolism in essential hypertension is generally well known (Baldwin et al., 1559; Cottier et al., 1958; Green et 3l., 1954).

Since Goldblatt et al. (1934) observed an important role of the ischemic kidney in renal hypertension, extensive efforts have been focused in isolating the pressor substance and now it is well known as angiotensin(Page and Helmer, 1939; Skeggs et al., 1956). Currently, the retrain-angiotensin system has been the subject of a study for its physiological role in renal functions and sodium metabolism because it can cause a change in the renal hemodynamics as a result of constricting vascular smooth muscle (Gross and Bock. 1962; Helmer, 1964) and effects the sodium transport in the renal tubule directly (Laragh et al., 1953) and indirectly through a regulatory mechanism of aldosterone secretion (Davis et al., 1961; Genest, 1961).

In view of sodium regulatory factors in man mentioned above and high sodium intake in the Koreans, it is worthwhile to study the dynamic aspect of sodium metabolism by measuring the turnover rate and the amount of exchangeable sodium along with the secretory activity of hormones such as aldosterone and lenin-angiotensin. Furthermore it is expected to get some insight into the pathogenesis of essential hypertension by comparing the results obtained from patients with essential hypertension to those of healthy Koreans.

Materials and methods

Normal volunteers (medical students) and patients with uncomplicated essential hypertension, 10 subjects from each group, were selected for this studs. An ordinary Korean diet (high salt diet) was supplied and medications, if any, were discontinued at least one week prior to this study. Salt intake was then reduced to less than 5 gm. per day for a period of 5 days.

Plasma lenin activity (PRA) and the amount of urinary aldosterone excreted in 24 hours were measured on the 3rd day of high sodium intake and on the 5th day of the low sodium regimen.

By repeating all of the above schedules, the total exchangeable body sodium store and it's turnover rate were determined in the corresponding periods of plasma lenin activity and urinary aldosterene measurements.

PRA was measured by radioimmunoassay method of Haber et .al. (1969), and urinary aldosterone excretion was determined by double isotope derivative assay method of Kliman and Peterson(1960).

Total exchangeable body sodium store and the turnover rate were measured with (22)**Na by the method of Adesman et al. (1960).

Results and conclusions

1) The mean blood pressures of both control and hypertensive groups were significantly decreased after 5 days of low salt diet compared to those checked haying a normal diet.

2) PRA for the control group was significantly elevated after sodium restriction compared to that found having a high salt diet. On the contrary, PRA for the hypertensive patients was not significantly increased with sodium restriction.

Regardless of high or low sodium intake, PRA measured in the control group was significantly higher than that found in the hypertensive group.

3) OR the high salt diet, Urinary aldosterone excreted in 24 hours was not Significantly different between the healthy and the hypertensive groups. However, the amount of daisy urinary aldosterone excretion in both groups was significantly increased after the administration of a low salt diet. This increase of urinary aldosterone excretion was particularly remarkable in the hypertensive group.

4) Plasma sodium concentrations measured in both groups were not significantly changed regardless of high or low sodium intake.

5) The amount of daily urinary sodium excretion in the hypertensive patients was significantly higher than that measured in the control group on a liberal Korean diet. On the other hand, there was no significant difference in the daily urinary sodium excretion between the two groups on sodium restriction.

6) PRA measured in the control group was inversely correlated with the daily urinary sodium excretion, but the patient group showed persistently low PRA

regardless of high or low urinary sodium excretion. On the other hand, daily urinary aldosterone excretions in both control and patient groups were inversely correlated with urinary sodium excreted in 24 hours.

7) The total exchangeable body sodium stoles were net significantly different between the control and the hypertensive patient groups regardless of high or low sodium intake. On the contrary, the disappearance rate of plasma (22)**Na in hypertensive patients during low sodium diet revealed somewhat an accelerated tendency in comparison with that found in normal subjects.

In view of the above experimental findings, the regulatory mechanism of aldosterone secretion in the patients with essential hypertension may be different from that of the control group. That is, the retrain-angiotensin system in the hypertensive patients may play a minor role in the regulation of aldosterone

secretion compared to normal subjects.

Furthermore it is speculated that the sensitivity of renal tubules to aldosterone in patients with essential hypertension is reduced compared to that of normal Korean healthy subjects.