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Biomedical subjects

S Ljungman

Publications and source records attributed to S Ljungman.

52 records · Page 3Linked to original sources
PubMed1982

Blood pressure in relation to the renin-angiotensin-aldosterone system.

The relationship between blood pressure (BP) and the renin-angiotensin-aldosterone system was studied in a stratified random sample (n=120) of 49-year-old men selected from a BP screening and covering a wide range of BPs. Only subjects not on antihypertensive treatment were included. None had malignant or secondary hypertension. Plasma renin activity, plasma concentrations of angiotensin II, aldosterone, sodium, potassium and noradrenaline and the 24-hour urinary excretions of sodium, cortisol and noradrenaline were determined. Of these variables, only p-aldosterone was significantly correlated wtih BP, both in the whole study group (R=0.22, p less than 0.02, n=119) and in the subjects with the highest BP range (R=0.36, p less than 0.02, n=30). Of the clinical groups compared, the hypertensive subjects had significantly higher mean p-aldosterone than the borderline and normotensive subjects. Multiple regression analysis showed that the 24-hour urinary excretion of noradrenaline was the factor most strongly correlated to p-aldosterone, suggesting that the sympathetic nervous system might stimulate aldosterone secretion. Our findings indicate that aldosterone may be of importance for the development and maintenance of essential hypertension.

Aldosterone↗
PubMed1981

Blood pressure and the renin--angiotensin--aldosterone system.

1. The relationships between blood pressure and the components of the renin--angiotensin--aldosterone system were studied in 49-year-old men (n = 120) who were selected at random from the total population so as to be representative of all blood pressure levels. 2. Only plasma aldosterone concentration was significantly correlated with blood pressure, both in the whole study group (r = 0.22; P less than 0.02) and in the hypertensive blood pressure range (r = 0.36; P less than 0.02). The hypertensive subjects had a significantly higher plasma aldosterone concentration than the borderline and normotensive subjects. 3. Multiple regression analysis including factors related to the renin--angiotensin--aldosterone system, showed that the 24 h urinary excretion of noradrenaline was the factor most strongly correlated to plasma aldosterone. 4. The findings indicate that aldosterone may be the most important component of the renin--angiotensin--aldosterone system in the development and maintenance of essential hypertension.

Aldosterone↗
PubMed1980

Blood pressure and renal function.

The relationship between blood pressure (BP) and renal function was studied in samples of 49-year-old men. Of 3 205 49-year-old men, 2 376 (74%) took part in a BP screening. By systematic sampling, based on diastolic BP levels varying from very low to very high, 120 subjects were selected for this study. Only subjects who were not on antihypertensive treatment were included. Renal blood flow (RBF), renovascular resistance (RVR), glomerular filtration rate (GFR), filtration fraction (FF) and renal concentrating capacity were studied in 111 subjects, none of whom had advanced hypertension. With increasing BP there was a decrease in RBF (r = -0.34) and an increase in RVR (r = 0.81) and FF (r = 0.35). The changes in renal haemodynamics occurred gradually from low to high BP, and did not start at any particular BP level. With increasing BP, GFR was unchanged. An "autoregulation of GFR" was thus found at all BP levels studied. Renal concentrating capacity was unchanged. These findings indicate that renal haemodynamics in essential hypertension are adjusted mainly to ensure a constant GFR.

Blood Pressure↗
PubMed1979

Heart and kidney involvement and prognosis in hypertension. A study concerning referred hypertensive patients and hypertensive patients found by blood pressure screening.

Severity of hypertension, frequency of secondary hypertension and prognosis have been compared in two groups of hypertensive men. The first group (n=686) was taken from a blood pressure screening of a total population sample. The other group (n=154) consisted of hypertensive men, referred to a hypertension clinic by physicians. The mean age of the groups was the same, (X=52 years, range 46--59 years). All went through the same investigations and were followed up and treated in a similar way at the hypertension clinic. The referred men had more severe hypertension, as shown by significantly more heart and kidney involvements. They also had a higher incidence of myocardial infarction, implying a poorer prognosis with regard to cardiovascular disease. The analysis shows the importance of a detailed description of studied groups, not only in terms of blood pressure, age and sex, but also with respect to the frequency and degree of present and previous signs of heart and kidney involvement. With such a description it is possible to compare results from different studies regarding pathophysiological mechanisms and the effect of treatment in hypertension.

Cerebrovascular Disorders↗
PubMed1977

Sodium excretion and sympathetic activity in relation to severity of hypertension.

The relationship between the severity of hypertensive disease and sodium excretion and sympathetic activity has been studied in normotensive (n = 19) and hypertensive (n = 19) men of the same derived from screening a total population. Sympathetic activity was determined from noradrenaline excretion and the severity of hypertension was assessed by measuring resting diastolic BP, left ventricular hypertrophy on orthogonal ECG and the glomerular filtration rate. In the hypertensive group the resting BP correlated well both with signs of left ventricular hypertrophy, i.e. with the degree of severity of the hypertensive disease. Up to the level of 90 mm Hg resting diastolic BP, sodium excretion rose in agreement with theory of pressure diuresis. Above 90 mm Hg, however, both sodium and noradrenaline excretion fell with increasing BP. This indicated that in more advanced hypertension the sodium balance overrides the sympathetic activity in the long-term relation of BP. In another series of 49-year-old-men noradrenaline excretion fell with increasing renal vascular resistance indicating that the increase in the latter variable could not be explained by increased sympathetic tone. On the basis of the results a hypothesis on the sequence of events leading to development of hypertension, is presented.

Blood Pressure↗
PubMedDate not supplied

The kidney as a target of hypertension.

In spite of improvement in blood pressure control during the last decades, the incidence of hypertension-related end-stage renal disease (ESRD) is reported to have increased and has become a common cause of renal failure, especially in the United States, but also in several other countries. The clinical diagnosis of hypertensive nephrosclerosis is usually presumptive, and an important differential diagnosis in older hypertensive persons is atheromatous renal vascular disease. Many studies of renal function in treated essential hypertension have shown a small and clinically insignificant decline in glomerular filtration rate (GFR). Recent long-term studies indicate that the change in GFR may be nonlinear, with a greater fall in GFR after initiation of antihypertensive treatment, followed by a phase of minimal or normal loss of GFR. There are no available prospective studies indicating that well-treated essential hypertension leads to renal failure, but there are new data indicating that patients with nonmalignant essential hypertension without any underlying renal disease and with early and good blood pressure control do not develop renal failure.

Glomerular Filtration Rate↗
PubMedDate not supplied

Type of obesity and blood pressure.

To explore the relationship between blood pressure on the one hand and body composition variables and fat cell size and number on the other, these factors were determined in a population sample (n = 120) of 49-year-old men with blood pressure (BP) ranging from very low to very high. BP increased linearly with body weight throughout the entire BP range, while body fat and fat cell size increased with increasing BP in the nonhypertensive but not in the hypertensive BP range. Body cell mass and fat cell number were unrelated to BP. Fat cell size (but not fat cell number) was positively correlated with most variables of glucose metabolism. It can be concluded that in normal men: the previously well-established relationship between body weight and BP is explained by an association between body fat and BP; BP is positively correlated with increased fat cell size, indicating hypertrophic obesity, while BP is unrelated to fat cell number; and increased fat cell size is associated with impaired glucose tolerance and hyperinsulinemia. The results point to the possibility that hypertrophic obesity and essential hypertension may be related to each other via common pathogenetic mechanisms.

Adipose Tissue↗
PubMedDate not supplied

Effects of subpressor doses of angiotensin II on renal hemodynamics in relation to blood pressure.

The renal hemodynamic response to subpressor doses of angiotensin II (AII; 0.1 and 0.5 ng/min/kg) was investigated in untreated 49-year-old men (n = 50) representing a wide blood pressure range. Renal blood flow, renal vascular resistance (RVR), glomerular filtration rate (GFR), filtration fraction (FF), plasma renin activity (PRA), plasma AII, plasma aldosterone, and the urinary excretion of sodium and norepinephrine were studied. The higher the initial blood pressure the greater was the increase in RVR in response to AII infusion (p less than 0.002), indicating an increased renal vascular reactivity with increase in initial blood pressure. The AII infusion gave a significant rise in RVR in both the borderline and hypertensive group, but gave no increase in RVR in the normotensive group, implying an enhanced sensitivity of the renal vasculature in the borderline and hypertensive group. The increase in RVR was greater in the hypertensive than in the borderline group, i.e., the hypertensives had a steeper dose-response curve than the borderline group, which points to the presence of structural vascular changes in the renal vessels in the hypertensives. The increase in RVR in response to AII was positively correlated to sodium intake and plasma aldosterone concentration, indicating that these two factors might modulate the renal vascular reactivity. These factors could, however, only partly explain that RVR increased more the higher the initial blood pressure. Thus, the results indicate that there is an increased reactivity of the renal vascular bed to AII in essential hypertension. The increased reactivity seems to be mediated through an increased sensitivity of the renal vasculature to AII in mild essential hypertension and also through the presence of structural vascular changes in established hypertension. These factors may lead to a reduced excretion of sodium and water and may therefore be of importance in the development and progression of essential hypertension.

Aldosterone↗
PubMedDate not supplied

Diastolic function of the heart in untreated primary hypertension.

To study left ventricular (LV) diastolic function of the heart in relation to blood pressure (BP) and other signs of hypertensive cardiac and peripheral vascular changes, isovolumic relaxation time and early diastolic filling were determined in four BP groups of untreated 49-year-old men: normotensive subjects (n = 20), men with borderline hypertension (n = 30), mild hypertension (n = 45), and moderate to severe hypertension (n = 24). Isovolumic relaxation time, measured as the distance between aortic closure (A2, phonocardiography) and mitral valve opening (echocardiography), and early diastolic filling, measured as the distance between mitral valve opening and the O point of the apexcardiogram, tended to increase with BP level, and the total interval from aortic closure to the O point (A2O interval) was significantly prolonged in the two groups with mild and moderate to severe hypertension. A prolonged A2O interval (greater than or equal to 117% of expected value at observed heart rate) was seen in several hypertensives, who had no obvious increase in LV wall thickness on M mode echocardiography. This suggests that a prolonged LV relaxation time may be an early sign of cardiac involvement in primary hypertension. In the group with moderate to severe hypertension, an increase in LV wall thickness was seen together with an increase in resistance at maximal dilation in the calf. This supports the theory that when changes in cardiac structure develop they occur in parallel with structural changes also in the periphery.

Blood Pressure↗
PubMedDate not supplied

Monitoring 24-hour blood pressure in a drug trial. Evaluation of a noninvasive device.

To test the usefulness of noninvasive ambulatory 24-hour blood pressure recording, the Del Mar Avionics system was used in a double-blind clinical trial in which 31 hypertensive patients were randomly allocated to receive placebo or pafenolol (25 mg or 50 mg), a novel, long-acting, highly selective beta-blocker, once daily. The results of 24-hour blood pressure and heart rate recording after 4 weeks of treatment were compared with a previous 24-hour recording performed after a 4-week placebo run-in period using the 3-hour mean of recordings performed every 7.5 minutes both day and night. Furthermore, 24-hour means were analyzed in each patient before and after 4 weeks. The system was easy to use and, judging from two placebo periods in the same patients, the reproducibility was good. The 24-hour blood pressure and heart rate recordings showed a clear dose-response relationship for pafenolol that could not be detected by ordinary casual readings. A daily dose of 25 mg of pafenolol significantly reduced blood pressure during the 9 hours after tablet intake (p less than 0.01), while 50 mg per day of pafenolol resulted in a significant reduction throughout the 24-hour period (p less than 0.01). The same pattern was seen for heart rate, which indicates a greater degree of beta-blockade during treatment with the higher dose. These results indicate that the tested noninvasive equipment is a useful tool for monitoring ambulatory 24-hour blood pressure. It gives important information impossible to obtain from single casual readings. This noninvasive method should be further evaluated to define its place in clinical work and as a research tool.

Adult↗