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Biomedical subjects

R Lammintausta

Publications and source records attributed to R Lammintausta.

70 records · Page 4Linked to original sources
PubMed1979

Alpha- and beta-adrenoceptor blocking properties of labetalol in renin release.

The effect of labetalol, an alpha- and beta-adrenergic receptor blocking antihypertensive, on plasma renin activity (PRA) and the hemodynamics of healthy volunteers at rest and during an ergometric exercise test was studied. Oral doses of 200 and 400 mg labetalol were tested against a placebo in a crossover manner. The labetalol plasma concentrations were determined. Systolic and diastolic blood pressures in the supine position decreased after 400 mg labetalol as did the response of the heart rate to exercise. The lower dose decreased the resting heart rate, but had no effect on the heart rate during exercise. The ergometric exercise induced an increase in PRA which was partly inhibited after 200 mg labetalol in a manner similar to that induced by beta-blockers in our earlier studies. After 400 mg labetalol PRA was already increased at one hour at sitting rest and this higher basal level was maintained for four hours. After this higher dose of labetalol the reaction of PRA to exercise was not significantly inhibited. In renin release the vasodilating alpha-blockade thus dominated the beta-blocking property of labetalol at the dose which decreased the blood pressure.

Adrenergic alpha-Antagonists↗
PubMed1979

The pharmacokinetics of dapsone and acetylated dapsone in serum and saliva.

The concentrations of dapsone (DDS) and its acetylated derivatives (MADDS and DADDS) were determined in the serum and saliva after one oral dose of dapsone until 72 hr. The peak serum concentrations of DDS and MADDS were reached, on average, at 3.8--4.3 hr after the dosage. The amounts of DADDS were negligible. The elimination half-life of the first order kinetics was, on average, at 20--21 hr for both DDS and MADDS. The study group included 6 rapid acetylators and 4 slow acetylators with the mean ratios MADDS/DDS 1.0 and 0.19, respectively. No difference in the pharmacokinetics of DDS or MADDS could be seen between the rapid and slow acetylators. The protein-free fractions of DDS and MADDS were 50 and 41 per cent, respectively, of the total serum concentrations as measured at 8 and 32 hr after the dosage. The salivary concentration of DDS was, on average, 49 per cent of the total serum concentration during the whole study period. The salivary concentration of MADDS was 40 per cent, respectively. The elimination half-life of DDS and MADDS in saliva did not differ from that in serum. Between the salivary and serum protein-free concentrations a strict correlation existed (p less than 0.001). The salivary concentration of dapsone and its monoacetyl derivative reflect the protein-free, active drug in serum.

Acetylation↗
PubMed1979

Effect of spironolactone treatment on the renin-aldosterone system during pregnancy.

Ten pregnant patients were treated with spironolactone (100 mg daily) for two weeks. The patients were on a continuous long-term saluretic therapy for pregnancy edema. In addition, a potassium supplementation (30 mmol/day) was given until the beginning of spironolactone treatment. The patients thus treated had a mean urinary aldosterone excretion (dU-Aldo) of more than ten-fold in comparison to that of non pregnant state. Canrenone, the effective conversion product of spironolactone in plasma, reached its steady state level in three days as in non-pregnant subjects. dU-Aldo decreased in two weeks during the spironolactone by 36% (p less than 0.05). The inhibition of aldosterone secretion is thus evident also after a low clinical dose of spironolactone. Urinary potassium excretion (dU-K) decreased during the 1st day (p less than 0.05) and continued to decrease during one week of spironolactone therapy by a total of 21% (p less than 0.001). The decrease in dU-K reflects the cessation of potassium supplements in the beginning of the study. No changes in urinary sodium excretion were found. Plasma renin activity (PRA) increased in one week by 79 per cent and the changes of PRA and dU-Aldo showed inverse correlation (p less than 0.001). In our study natriuresis, cannot explain the increase of PRA. Our study suggests another feedback effect of aldosterone.

Aldosterone↗
PubMed1978

The effect of estriol succinate therapy on plasma renin activity and urinary aldosterone in postmenopausal women.

The effects of estriol succinate (Synapause, 2 mg daily) on the renin-aldosterone system and blood pressure (RR) were studied in 14 postmenopausal women after bilateral oophorectomy. Plasma renin activity (PRA) and daily urinary aldosterone excretion (dU-Ald) were determined 1 mth after the operation and before estrogen treatment, at the end of 2 mth therapy, and, for the third time, 2 mth after the termination of treatment with the drug. No changes in PRA, dU-Ald or RR were found in normotensive women, or in 3 women with hypertension in this group. Another group of 11 postmenopausal women was investigated after long-term estriol succinate therapy, which had lasted for 5-8 yr after oophorectomy. PRA, dU-Ald and RR were measured during treatment and 2 mth after terminating the therapy. No changes were found either in hormone differences in the mean levels of PRA or dU-Ald. The results suggest that estriol succinate is devoid of general harmful effects on the renin-aldosterone system during postmenopausal therapy for climacteric symptoms.

Aldosterone↗
PubMed1978

Effect of intravenous infusion of betasympathomimetic agents on plasma renin activity during pregnancy.

The plasma renin activity (PRA) was measured in 26 pregnant patients before and during ritodrine infusion (10 patients), during isoxsuprine infusion (12 patients), and during glucose infusion (4 control patients). All patients were in the third trimester of pregnancy, not in labour and not hypertensive. A low dose of ritodrine, a beta2 adrenergic agent, caused a rise of PRA but no simultaneous rise in heart rate; this suggests that beta2 activity is involved in renin release. Normal doses of ritodrine and isoxsuprine increased the maternal heart rate to 110 to 120 beats/minute and also doubled the PRA level. Two hours after the end of the ritodrine infusion the PRA level was still above that before the infusion. The results suggest high reserves of renin during pregnancy.

Adrenergic beta-Agonists↗
PubMed1978

Urinary electrolyte profiles after amiloride, hydrochlorthiazide and the combination.

Acute effects of amiloride (5 mg) (A), hydrochlorthiazide (50 mg) (H) and the combination (50 + 5 mg) (HA) on urinary electrolyte excretion and pH of ten healthy volunteers--taking placebo five times and twice randomly A and HA and once H--were studied during one day. Amiloride showed a natriuretic effect, which in combination was additive to that of hydrochlorthiazide, but the excretion of water did not increase significantly after A. The urinary excretion of potassium decreased with amiloride below normal levels and was at the level of placebo after the combination (HA). There was a striking linear correlation between urinary sodium and potassium with all the drugs, although showing with A a higher potassium retention during high sodium excretion. Urinary pH rose after A and HA during the first 8 hours, but this effect was not seen, however, after H. No significant differences in the effect of the two brands of A (Medamor and Puritrid) on the urinary electrolyte excretion and pH, nor in those of the two brands of HA (Moduretic and Amitrid) were found. Similarly, the plasma concentrations of hydrochlorthiazide, determined gas chromatographically, were equal after Moduretic and Amitrid tablets. The systemic availability of H was faster in the combination of HA than alone. In the AUC value of H, however, there was no significant difference between HA and H tablets.

Adolescent↗
PubMed1978

Effect of chlorthiazide treatment on renin-aldosterone system during pregnancy.

Plasma renin activity and urinary excretions of aldosterone, sodium and potassium were studied before and during one week's chlorthiazide treatment in eight women with a slight peripheral oedema in the 31st week of pregnancy. Plasma renin activity and excretion of aldosterone increased clearly on the first day of treatment, but on the 7th day it was more than doubled in comparison with the level before the treatment. Diuresis and excretion of sodium increased promptly on the 1st day, but did not differ from the level found before the treatment on the 7th day. The high reserves of renin and aldosterone secretion found in this study may be regarded important in ensuring blood pressure, plasma volume and placental flow during pregnancy.

Adult↗
PubMed1978

The renin-aldosterone system in dihydralazine therapy during hypertensive pregnancy.

Ten patients with hypertensive pregnancy were studied in hospital for 3 weeks. Plasma renin activity (PRA), the daily urinary excretion of aldosterone (dU-Aldo) and electrolytes were studied before and during dihydralazine therapy (25 mg 3 times daily). In one week the supine blood pressure decreased (p less than 0.05) without any discernible tachycardia. PRA increased in 3 days of the treatment by 50% (p less than 0.05) and this mean level was maintained. In dU-Aldo no change was found, however, during the study; and the excretions of sodium and potassium remained unchanged as well. In patients without diuretic therapy the basal PRA level before dihydralazine therapy was lower than in normal pregnancy. Also, in patients with preceding diuretic therapy the basal level of PRA was lower than during diuretics in gravidas without hypertension. Judging from the animal experiments, the rise in PRA might be seen as favorable for uteroplacental circulation in pregnancy hypertension.

Adult↗
PubMed1978

Estimation of pharmacokinetic parameters of digoxin from serum, saliva and urine.

The pharmacokinetics of digoxin was studied in 14 healthy volunteers using concentrations measured radioimmunologically in the serum, saliva and urine. The subjects were given 0.75 mg of digoxin intravenously. Serum and saliva were obtained over a 72 hr period and urinary excretion rates over 6 or 7 days. Binding of digoxin to serum proteins was determined by ultracentrifugalization. A linear correlation between the serum and saliva concentrations was found. Salivary levels were equal to the unbound fraction in the serum. The half-lives of distribution did not differ between the serum and saliva. An erroneously short half-life of elimination was found in the serum, but in the saliva and urine it was found to be in the range previously reported. Salivary level measurements may be useful in pharmacokinetic studies and may have important clinical implications.

Adolescent↗
PubMed1978

Renin-aldosterone system and urinary electrolytes after amiloride, hydrochlorothiazide and the combination.

Plasma renin activity (PRA), urinary aldosterone excretion (U-Ald) and electrolyte excretions were studied after a placebo (P) (n = 47) and during the following day randomly after amiloride (A) (5 mg, n = 18), hydrochlorothiazide (H) (50 mg, n = 12) and hydrochlorothiazide + amiloride tablets (HA) (50 + 5 mg, n = 19). After A no change in PRA or in U-Ald could be found in 24 hr. After H an increase in PRA was found, but not until 24 hr, and U-Ald was increased during 8--24 hr. HA possessed a higher saluretic effect than H, but the excretion of potassium was lower. PRA increased in 8 hr after HA and a further increase was seen until 24 hr. U-Ald had already increased after HA during 0--8 hr, and U-ALD was higher during 8--24 hr and 0--24 hr than after H. After HA a positive correlation was found between the increases of sodium excretion and PRA; between U-Ald and PRA a positive correlation was also found; but between potassium excretion and PRA or U-Ald there was no correlation. The results suggest the priority of natriuresis in the regulation of renin release after H and HA. The stronger reaction of the renin-aldosterone system after HA than after H thus may result from the faster and higher natriuretic potency of this combination in acute study.

Adolescent↗
PubMed1977

The effect of normal labor on the renin-angiotensin system in mother and fetus.

Plasma renin activity (PRA) and angiotensin I concentration (AI) in mother, umbilical vessels, and amniotic fluid were measured during 11 elective cesarean sections and after 12 normal labors. During cesarean section, PRA and AI were significantly lower in umbilical vessels than in mother or in amniotic fluid. This finding reflects the steady state in the late pregnancy. PRA and AI were significantly higher in the umbilical vessels after normal labor in comparison to the levels of cesarean section. In the mother there was no difference in PRA after normal labor and during cesarean section, but AI was significantly higher after normal labor. After normal labor no difference of PRA between mother, umbilical vessels, and amniotic fluid was found. The rise of fetal PRA and AI as a reaction to uterine contractions may be of great importance in ensuring the fetoplacental circulation during the labor.

Amniotic Fluid↗
PubMed1977

Selective and non-selective beta-blockade in renin release.

The effects of two beta-adrenergic receptor blocking drugs, the non-selective propranolol and the beta1selective metoprolol, were studied on hemodynamics and plasma renin activity (PRA) of healthy volunteers in an ergometric exercise test. Oral doses of 160 mg of propranolol and 200 mg of metoprolol were tested against placebo. The drug plasma concentrations were determined. Heart rate and systolic blood pressure were equal and significantly lower during treatment with both active drugs when compared to placebo. The effect of drugs on exercise heart rate was correlated with the logarithm of drug plasma concentration with both propranolol and metoprolol. Propranolol, but not metoprolol, decreased the basal level of PRA. The ergometric exercise induced a significant rise in PRA after placebo but this increase was partially inhibited by the both active drugs. On the basis of these findings it is suggested that in man the basal level of PRA could be decreased mainly by blocking the beta2-adrenoceptors. Instead the exercise induced increase of PRA could be inhibited by blocking the beta1-adrenergic receptors.

Administration, Oral↗
PubMed1977

Cardioselective (metoprolol) and non-selective (propranolol) beta-blockade and glucose homeostasis.

The effects of two beta-adrenergic receptor blocking drugs, the non-selective propranolol and the cardioselective metoprolol, on the concentrations of blood glucose, serum insulin (IRI) and growth hormone (GH) were studied in 8 healthy male volunteers both at rest and on exercise. The tablets of 160 mg of propranolol and 200 mg of metoprolol were tested against a placebo. The heart rate and systolic blood pressure were significantly lower during treatment with the active substances than with placebo. There were no significant differences between the blood glucose and serum IRI levels after the compounds and the placebo. A decreased insulin/blood glucose ratio after exercise was seen during metoprolol. The serum GH levels were of about the same magnitude after the three different treatments but the peak values were seen 30 and 40 minutes earlier after propranolol and metoprolol than after the placebo. The concentrations of the drugs in plasma did not correlate significantly with the changes in serum levels of IRI and GH in the exercise test. In the present acute test situation propranolol and metoprolol did not significantly affect glucose homeostasis and there were no apparent differences between the drugs.

Adult↗
PubMed1977

Renin-angiotensin--aldosterone system and sodium in normal pregnancy: a longitudinal study.

Plasma renin activity, the concentration of angiotensin I and the urinary excretion of aldosterone and sodium were studied longitudinally in 10 healthy primigravidae from the 10th week of pregnancy monthly until the 7th puerperal day. Plasma renin activity and angiotensing I levels were significantly elevated throughout pregnancy and showed maximal mean values at the 10th week, gradually returning to the level of nonpregnant women 7 days after delivery. They daily urinary excretion of aldosterone was also increased throughout pregnancy, but the mean values showed an increasing trend until 34th week. They returned to nonpregnant levels 7 days after delivery. There were no significant changes in the urinary excretion of sodium during pregnancy but the mean value was lower than in the nonpregnant control group. There was a significant positive correlation between urinary aldosterone and sodium values, while an almost significant negative correlation existed between urinary aldosterone and plasma renin activity, suggesting the priority of natriuresis in the regulation of aldosterone secretion during pregnancy. No corrleation was found between plasma renin activity and urinary sodium excretion values.

Adult↗
PubMed1976

Change in hormones reflecting sympathetic activity in the Finnish sauna.

The effects of the high temperature (80-120 degrees C) of the Finnish Sauna bath on the concentrations of growth hormone, immunoreactive insulin and renin activity in plasma, on blood glucose and on the urinary excretion of aldosterone, vanilmandelic acid and sodium of 55 healthy volunteers were studied. There was a significant increase in mean heart rate (62%), serum growth hormone (142%) and plasma renin activity (95%) in the Sauna. One hour after the Sauna bath the mean serum growth hormone had returned to the control level while plasma renin activity still remained higher (p less than 0.05) than before the Sauna bath. The serum insulin, blood sugar and urinary excretion of aldosterone and VMA did not change during or after Sauna bath. The urinary sodium excretion decreased significantly after the Sauna bath and the decrease was most striking (46%) during the first 6-hour period from the beginning of Sauna bath. Plasma renin activity values correlated positively with 12-hour urinary VMA excretion (p less than 0.01) and negatively with 6-hour urinary sodium excretion (p less than 0.05) before and after Sauna, suggesting the role of catecholamines and sodium depletion in renin response in Sauna.

Aldosterone↗