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Biomedical subjects

K H Rahn

Publications and source records attributed to K H Rahn.

At least 127 records · Page 7Linked to original sources
PubMed1991

Na+, K(+)-ATPase inhibition and intracellular electrolyte content in essential and secondary hypertension.

A crucial role of humoral factors in the pathogenesis of primary hypertension is discussed. In 1982 Hamlyn et al demonstrated the presence of a Na+, K(+)-ATPase inhibitor in the plasma of essential hypertensives and showed a significant correlation of the Na+, K(+)-ATPase inhibition with the blood pressure. In this study we examined whether an Na+, K(+)-ATPase inhibitor could be found in the blood of essential hypertensives as compared to patients with secondary hypertension (renal hypertension, renal artery stenosis, pheochromocytoma). Second, the possible correlation between an inhibition of Na+, K(+)-ATPase and the intracellular electrolyte composition was examined. The results demonstrate a similar reduction of Na+, K(+)-ATPase inhibition in both essential hypertensives and secondary hypertensives as compared to normotensive controls. Further, the intracellular electrolyte composition (Na+, Na; K+, Ca) does not show a significant correlation to the degree of Na+, K(+)-ATPase inhibition, whereas a significant correlation between the degree of Na+, K(+)-ATPase inhibition and intracellular Cl- concentration could be demonstrated. The present study shows that an endogenous Na+, K(+)-ATPase inhibitor is also present in secondary forms of hypertension, thus implying that a specific role in the pathogenesis of primary hypertension for an Na+, K(+)-inhibitor is unlikely.

Adult↗
PubMed1991

Blood pressure elevation during the night in chronic renal failure, hemodialysis and after renal transplantation.

Diurnal blood pressure variation was studied by ambulatory 24-hour monitoring in patients with advanced chronic renal failure (n = 20), on chronic hemodialysis (n = 20), after renal transplantation (n = 21) and in matched control groups without renal disease. Nocturnal blood pressure reductions were significantly blunted in all patient groups as compared with the respective control groups. In almost none of the 61 controls did the mean values during nighttime (8 p.m.-8 a.m.) exceed the mean day time values (8 a.m.-8 p.m.). In 10 of the 61 renal patients blood pressure was higher during the night. In patients with chronic renal disease nocturnal blood pressure elevation may be diagnosed by ambulatory 24-hour monitoring. This may require adaptation of antihypertensive treatment.

Adult↗
PubMed1991

Cardiovascular side effects after renal allograft rejection therapy with Orthoclone: prevention with nitrendipine.

Orthoclone (OKT-3), a monoclonal antibody, is an effective immunosuppressant in organ graft recipients. One of the reported side effects is serious pulmonary edema, heart failure, hyperdynamia, and elevation of blood pressure. It should be assessed whether patients treated with OKT-3 benefit from antihypertensive therapy with a calcium channel blocker before and during the allograft rejection therapy to prevent from cardiovascular side effects. To assess a preventive cardiovascular effect of therapy with nitrendipine before and during the OKT-3 rejection therapy, the patients studied (n = 28) were randomly allocated to two study groups. Group a without nitrendipine comprised 15 patients, and group b with 2 x 10 mg of nitrendipine daily comprised 13 patients. In study group a (without nitrendipine therapy), in 8 of 15 patients, there was a short-lasting increase in blood pressure during 3 h after the first injection of OKT-3 by 20.0 +/- 12.8 (systolic)/10.1 +/- 6.7 (diastolic) mm Hg. Whereas this initial rise of blood pressure on the first day was accompanied by an increase in heart rate by 24.1 +/- 10.8 beats/min, the longer-lasting increase in blood pressure at day 2 was not associated with significant changes in heart rate. In group b (patients receiving 2 x 10 mg of nitrendipine before OKT-3 therapy was started and during the whole treatment course), in 3 of 13 patients, a short increase in blood pressure (13.7 +/- 2.9/7.8 +/- 5.1 mm Hg) was recorded 5 h after the first dose of OKT-3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Reference data for ambulatory blood pressure monitoring: what results are equivalent to the established limits of office blood pressure?

In 1039 subjects ambulatory blood pressure monitoring was performed to define threshold values, which are equivalent to the established limits of the office blood pressure. Mean values and proportions of elevated single readings were correlated to office blood pressure by regression analyses. To avoid impact of varying sleeping periods on 24 h blood pressure, only daytime readings were considered. Correlations between average daytime blood pressure and office blood pressure were linear: Mean daytime values of 135 mmHg (systolic) and of 84 mmHg (diastolic) were equivalent to the casual blood pressure limits of 140 mmHg and 90 mmHg. Correlations between percentages of elevated single readings and office blood pressure were nonlinear: Proportions of 25% systolic readings greater than 140 mmHg and of 17% diastolic readings greater than 90 mmHg were equivalent to casual blood pressure limits of 140 mmHg and 90 mmHg. On the basis of the regression equations, any result of ambulatory blood pressure recording during daytime can now be evaluated in terms of the established standards of office blood pressure.

Blood Pressure Monitors↗
PubMed1990

[Doctor's-office blood pressure, home blood pressure, ergometry blood pressure and 24-hour blood pressure. The correlations with the echocardiographic parameters of heart muscle mass].

In 62 untreated hypertensives (31 men, 31 women; median age 40 [17-57] years) blood pressures (BP) were measured in the doctor's office, at home (self-measured) and every 15 min during 24-hour monitoring (by portable automated oscillometry), the results being compared with echocardiographic measurements of ventricular septal thickness (VST), left ventricular muscle mass (LVM) and left ventricular mass index (LVMI), in 41 of them also during and 5 min after 100 W bicycle ergometry. In the total cohort, 24-hour values correlated better with diastolic VST (systolic: r = 0.706, P less than 0.00001; diastolic: r = 0.507, P less than 0.0001) than office BP (systolic: r = 0.381, P less than 0.01; diastolic: r = 0.177, not significant) and home BP (systolic: r = 0.477, P less than 0.0001; diastolic: r = 0.371, P less than 0.05). In the 41 exercised hypertensives the correlation with echocardiographic values was less close than with their 24-hour BP, but slightly better than with office and home BP. Systolic BP correlated better than diastolic BP with echocardiographic values. VST generally correlated better with BP than LVM and LVMI. It is concluded that (1) 24-hour BP values correlate more closely with LVM than any other noninvasive BP measurement; (2) VST is affected more by systolic than diastolic BP; and (3) VST more specifically reflects the influence of BP on myocardial structure than does LVM and LVMI.

Adolescent↗
PubMed1990

Principles of antihypertensive drug treatment.

The main objectives of chronic drug treatment in essential hypertension are to decrease blood pressure, improve prognosis, reduce the number and severity of adverse effects to a minimum, and use simple treatment schedules. Simple treatment schedules may be easily maintained with monotherapy (i.e., beta blockers, diuretics, calcium antagonists and angiotensin-converting enzyme inhibitors). If monotherapy is insufficiently effective, antihypertensive drugs can be combined. Combination therapy makes use of the synergistic effects of most antihypertensive drugs. Further considerations of combination therapy of antihypertensive agents are the inhibition of compensatory mechanisms working against blood pressure reduction and the decrease of the frequency and severity of adverse effects. Combinations of 2 antihypertensive agents usually contain a diuretic or a calcium antagonist.

Antihypertensive Agents↗
PubMed1990

[Morning rise in blood pressure: before or following awakening?].

The coincidence of the circadian peak of cardiovascular events with the morning blood pressure rise suggests causal connections. Rapidly acting antihypertensives taken before getting up may attenuate the increase early enough, if the onset does not occur before awakening. In 111 normotensives and in 109 subjects with untreated essential hypertension ambulatory blood pressure monitoring was performed to study whether the onset of the blood pressure rise occurs before or after waking up. The individual 24 h blood pressure profiles obtained by intermittent readings at intervals of 15 minutes were synchronized by the time of waking up. The resulting blood pressure curves showed no substantial blood pressure rise during sleep, but steep increases after awakening: Within the first hour after waking up blood pressure increased from 107.3 + 11.4/62.3 +/- 9.6 mm Hg (mean + sd) to 121.4 +/- 16.0/75.3 + 12.6 mm Hg in normotension and from 124.7 + 16.0/72.7 + 12.2 mm Hg to 140.3 + 17.2/84.5 + 13.3 mm Hg in hypertension. The velocity of this increase was dependent on the lag between waking up and getting up. There was no phase difference between early morning blood pressure and heart rate rises. Thus to attenuate the morning blood pressure increase, rapidly acting drugs after awakening may be considered instead of long acting antihypertensives administered prior to sleep.

Adult↗
PubMed1990

The influence of chronic treatment with verapamil on plasma atrial natriuretic peptide levels in young and elderly hypertensive patients.

In a double-blind, placebo-controlled cross-over study, the plasma atrial natriuretic peptide (ANP) levels of nine young and ten elderly hypertensive patients were compared after placebo and after treatment with 120 mg verapamil given three times daily over 4 weeks. During placebo, plasma ANP levels proved to be higher in elderly patients than in young subjects. Chronic treatment with verapamil induced a rise in ANP levels in both young and elderly patients with hypertension.

Adult↗
PubMed1990

The effect of verapamil on carotid artery distensibility and cross-sectional compliance in hypertensive patients.

The effect of chronic administration of verapamil, following a double-blind, crossover protocol, on the distensibility and cross-sectional compliance of the common carotid artery was investigated in 19 patients with essential hypertension. Distensibility was significantly increased during verapamil treatment as compared to placebo for both left and right common carotid artery (p less than 0.01 and p less than 0.05, respectively). The cross-sectional compliance was significantly increased during verapamil treatment for the right common carotid artery (p less than 0.05). For the left common carotid artery, the difference did not reach the level of significance (p = 0.16). The common carotid artery diameter and the arterial pulse pressure were not significantly different during verapamil treatment as compared with placebo. The results of this study indicate that chronic treatment with verapamil increases distensibility and cross-sectional compliance of the common carotid artery in hypertensive subjects. These improvements have to be considered as changes in arterial wall properties because no significant differences in pulse pressure and diameter could be detected between the verapamil and placebo periods. Improved arterial wall properties could result in a better management of the flow jet from the heart, and might protect the patients from atherosclerotic complications of hypertension.

Adult↗
PubMed1989

[Action of trichlormethiazide and amiloride on cellular Na+, K+ and Mg+ concentrations].

While diuretic-induced changes of plasma electrolyte concentrations have often been described, comparatively few data exist on intracellular electrolyte concentrations under diuretic treatment. Therefore, we studied the effect on intracellular Mg2+, Na+ and K+ concentrations of a thiazide diuretic (trichlormethiazide 4 mg/d) in red blood cells of 14 patients with mild essential hypertension, and of a combination of a thiazide diuretic and a potassium-sparing diuretic (trichlormethiazide and amiloride 2 mg/d each) in red blood cells of 11 patients with mild essential hypertension. Measurements were performed by atomic absorption spectroscopy and flame photometry before starting treatment and after 4 and 8-12 weeks' diuretic treatment. There was no significant change in intracellular Na+ and K+ concentrations under either form of diuretic treatment. Intracellular Mg2+ concentrations decreased significantly under thiazide therapy, whereas there was a significant increase in intracellular Mg+ concentrations under thiazide and potassium-sparing combined diuretic therapy. The results show that the combination of a thiazide diuretic and a potassium-sparing diuretic is a useful means to avoid intracellular Mg2+ loss.

Amiloride↗
PubMed1989

How should we treat a hypertensive emergency?

Hypertensive emergencies are life-threatening situations caused by acute blood pressure elevation. They require immediate treatment with antihypertensive drugs. Such emergencies include hypertensive crisis, acute left ventricular heart failure or intracranial bleeding in patients with hypertension, malignant hypertension resistant to treatment, and serious blood pressure elevations after vascular surgery. A hypertensive crisis may be defined as a sudden increase in systolic and diastolic blood pressure that causes functional disturbances of the central nervous system, the heart or the kidneys. In patients with hypertensive crisis, treatment should be started with an alpha receptor-blocking agent if pheochromocytoma has not been excluded by previous workup. Antihypertensive agents with a rapid onset of action--nifedipine, clonidine, dihydralazine, diazoxide and sodium nitroprusside--are being used.

Antihypertensive Agents↗
PubMed1989

Diurnal variations of blood pressure in shift workers during day and night shifts.

The dependence of blood pressure upon internal rhythms and the short-term effects of shift rota on the blood pressure were investigated in shift workers. Blood pressure was measured every 30 min using automatic records for 24h in 17 physically working men in a chemical factory during their morning and night shifts. There were no differences of the mean blood pressure between the respective sleeping phases or between the working periods. The amplitudes of circadian blood pressure variations were equal. There was a phase difference of 8h corresponding to the lag between the working periods. At this 8-h lag the hourly means of the 24-h blood pressure were closely correlated (r=0.69). Comparisons of 24-h blood pressure profiles during the first and last days of night shift week showed that the effects of night work on the blood pressure were already fully developed within the first 24h (r=0.86). Thus the diurnal variations of the blood pressure are determined by the working and sleeping periods and largely independent of endogenous rhythm. There is no short-term alteration of the mean 24-h blood pressure after shift rota.

Adult↗
PubMed1989

Pharmacokinetics of nitrendipine in terminal renal failure.

The pharmacokinetics and plasma protein binding of nitrendipine in patients with terminal renal failure have been compared with those in subjects with normal renal function. Kinetic parameters were calculated after a single 40 mg oral dose, an i.v. injection of 3 mg and after a 15 mg i.v. infusion of nitrendipine. Steady-state plasma levels were determined after 5 days of oral treatment with 20 mg b.d. Pharmacokinetic parameters and steady-state plasma levels in patients with renal failure did not differ from those in subjects with normal renal function. Nitrendipine was as highly bound to plasma proteins in patients with renal failure, as in subjects with normal renal function. The plasma protein did not differ between the two. The dosage of nitrendipine need not be modified for kinetic reasons in patients with renal failure.

Administration, Oral↗
PubMed1989

Total and free steady-state plasma levels and pharmacokinetics of nifedipine in patients with terminal renal failure.

The total and free steady-state plasma levels of nifedipine in patients with renal failure have been compared with those in subjects with normal renal function. Studies were done after administration of nifedipine 10 mg t.d.s. p.o. for 5 days, after i.v. infusion of 4.4 mg, and after a single 10 mg oral dose. The systemic clearance of nifedipine after a single i.v.-dose was higher in subjects with renal insufficiency (854 ml/min) than in those with normal renal function (468 ml/min). After the single oral dose the AUC (6100 ng.min.ml-1) and maximum plasma concentration (75.0 ng.ml-1) were lower than in subjects with normal renal function (19300 ng.ml-1; 122 ng.ml-1). The plasma protein binding of nifedipine averaged 95.5% in normal subjects and 94.8% in patients with renal failure. Although free and total steady-state plasma levels of nifedipine tended to be somewhat lower than normal in renal failure, the changes in pharmacokinetics and decreased protein binding of nifedipine did not result in a significantly different steady-state plasma level of the drug. The blood pressure response to a given plasma nifedipine level appeared to be enhanced in renal failure.

Administration, Oral↗
PubMed1989

Nocturnal hypertension in renal failure, haemodialysis and after renal transplantation.

Diurnal blood pressure variations in 20 patients with advanced renal failure, 20 patients on chronic haemodialysis, and 21 renal transplant recipients were compared with those of matched control groups without renal disease, using 24-h ambulatory blood pressure monitoring. Whereas the blood pressure during the day (from 8 a.m. to 8 p.m.) was roughly the same in the patients compared with their respective control groups, during the night (from 8 p.m. to 8 a.m.) it was substantially higher in all patient groups. The differences between the mean daytime and night-time values were significantly lower in the patients (P less than 0.05 to P less than 0.001). The nocturnal blood pressure decrease may be attenuated or even reversed in renal failure, in haemodialysis and after renal transplantation. In a proportion of these patients, 24-h ambulatory blood pressure monitoring showed an elevated nocturnal blood pressure, which may require some modification of treatment.

Blood Pressure↗